WorldWideScience

Sample records for high dark current

  1. SQUID based cryogenic current comparator for measurements of the dark current of superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Vodel, W.; Nietzsche, S.; Neubert, R.; Nawrodt, R. [Friedrich Schiller Univ. Jena (Germany); Peters, A. [GSI Darmstadt (Germany); Knaack, K.; Wendt, M.; Wittenburg, K. [DESY Hamburg (Germany)

    2005-07-01

    The linear accelerator technology, based on super-conducting L-band (1.3 GHz) is currently under study at DESY (Hamburg, Germany). The two 10 km long main Linacs will be equipped with a total of nearly 20.000 cavities. The dark current due to the emission of electrons in these high gradient field super-conducting cavities is an unwanted particle source. A newly high performance SQUID based measurement system for detecting dark currents is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the pA range with a measurement bandwidth of up to 70 kHz. The use of a cryogenic current comparator as dark current sensor has some important advantages: -) the measurement of the absolute value of the dark current, -) the non-dependence on the electron trajectories, -) the accurate absolute calibration with an additional wire loop, and -) extremely high resolution.

  2. Highly Sensitive Measurements of the Dark Current of Superconducting Cavities for TESLA Using a SQUID Based Cryogenic Current Comparator

    CERN Document Server

    Vodel, W; Nietzsche, S

    2004-01-01

    This contribution presents a Cryogenic Current Comparator (CCC) as an excellent tool for detecting dark currents generated, e.g. by superconducting cavities for the upcoming TESLA project (X-FEL) at DESY. To achieve the maximum possible energy the gradient of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The undesired field emission of electrons (so-called dark current) of the superconducting RF cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a highly sensitive LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measu...

  3. A new method of CCD dark current correction via extracting the dark Information from scientific images

    Science.gov (United States)

    Ma, Bin; Shang, Zhaohui; Hu, Yi; Liu, Qiang; Wang, Lifan; Wei, Peng

    2014-07-01

    We have developed a new method to correct dark current at relatively high temperatures for Charge-Coupled Device (CCD) images when dark frames cannot be obtained on the telescope. For images taken with the Antarctic Survey Telescopes (AST3) in 2012, due to the low cooling efficiency, the median CCD temperature was -46°C, resulting in a high dark current level of about 3e-/pix/sec, even comparable to the sky brightness (10e-/pix/sec). If not corrected, the nonuniformity of the dark current could even overweight the photon noise of the sky background. However, dark frames could not be obtained during the observing season because the camera was operated in frame-transfer mode without a shutter, and the telescope was unattended in winter. Here we present an alternative, but simple and effective method to derive the dark current frame from the scientific images. Then we can scale this dark frame to the temperature at which the scientific images were taken, and apply the dark frame corrections to the scientific images. We have applied this method to the AST3 data, and demonstrated that it can reduce the noise to a level roughly as low as the photon noise of the sky brightness, solving the high noise problem and improving the photometric precision. This method will also be helpful for other projects that suffer from similar issues.

  4. Dark current studies on a normal-conducting high-brightness very-high-frequency electron gun operating in continuous wave mode

    Directory of Open Access Journals (Sweden)

    R. Huang

    2015-01-01

    Full Text Available We report on measurements and analysis of a field-emitted electron current in the very-high-frequency (VHF gun, a room temperature rf gun operating at high field and continuous wave (CW mode at the Lawrence Berkeley National Laboratory (LBNL. The VHF gun is the core of the Advanced Photo-injector Experiment (APEX at LBNL, geared toward the development of an injector for driving the next generation of high average power x-ray free electron lasers. High accelerating fields at the cathode are necessary for the high-brightness performance of an electron gun. When coupled with CW operation, such fields can generate a significant amount of field-emitted electrons that can be transported downstream the accelerator forming the so-called “dark current.” Elevated levels of a dark current can cause radiation damage, increase the heat load in the downstream cryogenic systems, and ultimately limit the overall performance and reliability of the facility. We performed systematic measurements that allowed us to characterize the field emission from the VHF gun, determine the location of the main emitters, and define an effective strategy to reduce and control the level of dark current at APEX. Furthermore, the energy spectra of isolated sources have been measured. A simple model for energy data analysis was developed that allows one to extract information on the emitter from a single energy distribution measurement.

  5. Dark Current and Multipacting in the Photocathode RF Guns at PITZ

    CERN Document Server

    Hui-Han, Jang; Flöttmann, Klaus; Grabosch, H J; Hartrott, Michael; Krasilnikov, Mikhail; Michelato, Paolo; Miltchev, Velizar; Monaco, Laura; Oppelt, Anne; Petrosyan, Bagrat; Riemann, S; Roensch, Juliane; Schreiber, Siegfried; Sertore, Daniele; Staykov, Lazar; Stephan, Frank

    2005-01-01

    For photocathode rf guns, the amount of dark current depends on the cavity surface and the photocathodes. Smooth conditioning reduces the amount of dark current. Mechanical damages of the cathodes induce high dark current and chemical pollution changes emission properties of the cathode. Multipacting in the gun cavity changes the surface status of the cathodes and sometimes makes the gun operation impossible due to vacuum interlocks. In this paper, dark current and multipacting features of the rf gun are presented including experimental and simulation studies.

  6. Self-powered photogalvanic phosphorene photodetectors with high polarization sensitivity and suppressed dark current.

    Science.gov (United States)

    Li, Shuaishuai; Wang, Tao; Chen, Xiaoshuang; Lu, Wei; Xie, Yiqun; Hu, Yibin

    2018-04-26

    High polarization sensitivity, suppressed dark current and low energy consumption are all desirable device properties for photodetectors. In this work, we propose phosphorene-based photodetectors that are driven using photogalvanic effects (PGEs). The inversion symmetry of pristine phosphorene is broken using either application of an out-of-plane gate voltage or a heterostructure that is composed of the original phosphorene and blue phosphorene. The potential asymmetry enables PGEs under illumination by polarized light. Quantum transport calculations show that robust photocurrents are indeed generated by PGEs under a zero external bias voltage because of the broken inversion symmetry. These results indicate that the proposed photodetector is self-powered. In addition, the zero bias voltage eliminates the dark currents that are caused by application of an external bias voltage to traditional photodetectors. High polarization sensitivity to both linearly and circularly polarized light can also be realized, with extinction ratios ranging up to 102. The photoresponse of the proposed phosphorene/blue phosphorene heterostructure can be greatly enhanced by gating and is several orders of magnitude higher than that in gated phosphorene.

  7. Dark Matter Detection: Current Status

    International Nuclear Information System (INIS)

    Akerib, Daniel S.

    2011-01-01

    Overwhelming observational evidence indicates that most of the matter in the Universe consists of non-baryonic dark matter. One possibility is that the dark matter is Weakly-Interacting Massive Particles (WIMPs) that were produced in the early Universe. These relics could comprise the Milky Way's dark halo and provide evidence for new particle physics, such as Supersymmetry. This talk focuses on the status of current efforts to detect dark matter by testing the hypothesis that WIMPs exist in the galactic halo. WIMP searches have begun to explore the region of parameter space where SUSY particles could provide dark matter candidates.

  8. Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla

    CERN Document Server

    Knaack, K; Wittenburg, K

    2003-01-01

    A newly high performance SQUID based measurement system for detecting dark currents, generated by superconducting cavities for TESLA is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the nA range with a small signal bandwidth of 70 kHz. To reach the maximum possible energy in the TESLA project is a strong motivation to push the gradients of the superconducting cavities closer to the physical limit of 50 MV/m. The field emission of electrons (the so called dark current) of the superconducting cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. This contribution describes a Cryogenic Current Comparator (CCC) as an excellent and useful tool for this purpose. The most important component of the CCC is a high performance DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted ...

  9. Extra-high short-circuit current for bifacial solar cells in sunny and dark-light conditions.

    Science.gov (United States)

    Duan, Jialong; Duan, Yanyan; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2017-09-05

    We present here a symmetrically structured bifacial solar cell tailored by two fluorescent photoanodes and a platinum/titanium/platinum counter electrode, yielding extra-high short-circuit current densities as high as 28.59 mA cm -2 and 119.9 μA cm -2 in simulated sunlight irradiation (100 mW cm -2 , AM1.5) and dark-light conditions, respectively.

  10. SQUID Based Cryogenic Current Comparator for Measurements of the Dark Current of Superconducting Cavities

    CERN Document Server

    Vodel, W; Neubert, R; Nietzsche, S

    2005-01-01

    This contribution presents a LTS-SQUID based Cryogenic Current Comparator (CCC) for detecting dark currents, generated e.g. by superconducting cavities for the upcoming X-FEL project at DESY. To achieve the maximum possible energy the gradients of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The measurement of the undesired field emission of electrons (the so-called dark current) in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a high performance LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil (inner diameter: about 100 mm) for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measurement bandwidth of up to 70 kHz was achieved without the pick-up coil. Now, ...

  11. Simulation of forward dark current voltage characteristics of tandem solar cells

    International Nuclear Information System (INIS)

    Rubinelli, F.A.

    2012-01-01

    The transport mechanisms tailoring the shape of dark current–voltage characteristics of amorphous and microcrystalline silicon based tandem solar cell structures are explored with numerical simulations. Our input parameters were calibrated by fitting experimental current voltage curves of single and double junction structures measured under dark and illuminated conditions. At low and intermediate forward voltages the dark current–voltage characteristics show one or two regions with a current–voltage exponential dependence. The diode factor is unique in tandem cells with the same material in both intrinsic layers and two dissimilar diode factors are observed in tandem cells with different materials on the top and bottom intrinsic layers. In the exponential regions the current is controlled by recombination through gap states and by free carrier diffusion. At high forward voltages the current grows more slowly with the applied voltage. The current is influenced by the onset of electron space charge limited current (SCLC) in tandem cells where both intrinsic layers are of amorphous silicon and by series resistance of the bottom cell in tandem cells where both intrinsic layers are of microcrystalline silicon. In the micromorph cell the onset of SCLC becomes visible on the amorphous top sub-cell. The dark current also depends on the thermal generation of electron–hole (e–h) pairs present at the tunneling recombination junction. The highest dependence is observed in the tandem structure where both intrinsic layers are of microcrystalline silicon. The prediction of meaningless dark currents at low forward and reverse voltages by our code is discussed and one solution is given. - Highlights: ► Transport mechanisms shaping the dark current-voltage curves of tandem devices. ► The devices are amorphous and microcrystalline based tandem solar cells. ► Two regions with a current-voltage exponential dependence are observed. ► The tandem J-V diode factor is the

  12. Current and future searches for dark matter

    International Nuclear Information System (INIS)

    Bauer, Daniel A.

    2005-01-01

    Recent experimental data confirms that approximately one quarter of the universe consists of cold dark matter. Particle theories provide natural candidates for this dark matter in the form of either Axions or Weakly Interacting Massive Particles (WIMPs). A growing body of experiments is aimed at direct or indirect detection of particle dark matter. I summarize the current status of these experiments and offer projections of their future sensitivity

  13. Observation of dark-current signals from the S-band structures of the SLAC linac

    International Nuclear Information System (INIS)

    Assmann, R.; Decker, F.J.; Seidel, M.; Siemann, R.H.; Whittum, D.

    1997-07-01

    It is well known that the electro-magnetic fields in high-gradient RF structures can cause electron emission from the metallic structure walls. If the emitted electrons are captured and accelerated by the accelerating fields so-called dark-current is induced. Dark-currents have been measured and studied for various RF-structures. In this paper the authors present measurements of RF induced signals for the SLC S-band structures. For nominal gradients of 17 MV/m it is shown that the dark-current can be strong enough to significantly reduce the signal-to-noise ratio of the SLC beam wire scanners. They also show results from RF measurements in the dipole band. The measurements are compared to more direct observations of dark-current and it is tried to connect the results to possible effects on the accelerated particle beam

  14. Dark current of organic heterostructure devices with insulating spacer layers

    Science.gov (United States)

    Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

    2015-03-01

    The dark current density at fixed voltage bias in donor/acceptor organic planar heterostructure devices can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of an interfacial exciplex state. If the exciplex formation rate limits current flow, the insulating interface layer can increase dark current whereas, if the exciplex recombination rate limits current flow, the insulating interface layer decreases dark current. We present a device model to describe this behavior and illustrate it experimentally for various donor/acceptor systems, e.g. P3HT/LiF/C60.

  15. SU-F-T-554: Dark Current Effect On CyberKnife Beam Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H; Chang, A [Soonchunhyang University Hospital, Seoul (Korea, Republic of)

    2016-06-15

    Purpose: All RF linear accelerators produce dark current to varying degrees when an accelerating voltage and RF input is applied in the absence of electron gun injection. This study is to evaluate how dark current from the linear accelerator of CyberKnife affect the dose in the reference dosimetry. Methods: The G4 CyberKnife system with 6MV photon beam was used in this study. Using the ion chamber and the diode detector, the dose was measured in water with varying time delay between acquiring charges and staring beam-on after applying high-voltage into the linear accelerator. The dose was measured after the time delay with over the range of 0 to 120 seconds in the accelerating high-voltage mode without beam-on, applying 0, 10, 50, 100, and 200 MUs. For the measurements, the collimator of 60 mm was used and the detectors were placed at the depths of 10 cm with the source-to-surface distance of 80 cm. Results: The dark current was constant over time regardless of MU. The dose due to the dark current increased over time linearly with the R-squared value of 0.9983 up to 4.4 cGy for the time 120 seconds. In the dose rate setting of 720 MU/min, the relative dose when applying the accelerating voltage without beam-on was increased over time up to 0.6% but it was less than the leakage radiation resulted from the accelerated head. As the reference dosimetry condition, when 100 MU was delivered after 10 seconds time delay, the relative dose increased by 0.7% but 6.7% for the low MU (10 MU). Conclusion: In the dosimetry using CyberKnife system, the constant dark current affected to the dose. Although the time delay in the accelerating high-voltage mode without beam-on is within 10 seconds, the dose less than 100 cGy can be overestimated more than 1%.

  16. Dynamical dark energy: Current constraints and forecasts

    Science.gov (United States)

    Upadhye, Amol; Ishak, Mustapha; Steinhardt, Paul J.

    2005-09-01

    We consider how well the dark energy equation of state w as a function of redshift z will be measured using current and anticipated experiments. We use a procedure which takes fair account of the uncertainties in the functional dependence of w on z, as well as the parameter degeneracies, and avoids the use of strong prior constraints. We apply the procedure to current data from the Wilkinson Microwave Anisotropy Probe, Sloan Digital Sky Survey, and the supernova searches, and obtain results that are consistent with other analyses using different combinations of data sets. The effects of systematic experimental errors and variations in the analysis technique are discussed. Next, we use the same procedure to forecast the dark energy constraints achievable by the end of the decade, assuming 8 years of Wilkinson Microwave Anisotropy Probe data and realistic projections for ground-based measurements of supernovae and weak lensing. We find the 2σ constraints on the current value of w to be Δw0(2σ)=0.20, and on dw/dz (between z=0 and z=1) to be Δw1(2σ)=0.37. Finally, we compare these limits to other projections in the literature. Most show only a modest improvement; others show a more substantial improvement, but there are serious concerns about systematics. The remaining uncertainty still allows a significant span of competing dark energy models. Most likely, new kinds of measurements, or experiments more sophisticated than those currently planned, are needed to reveal the true nature of dark energy.

  17. Time Dependent Quantum Efficiency and Dark Current Measurements in an RF Photocathode Injector with a High Quantum Efficiency Cathode

    CERN Document Server

    Fliller, Raymond P; Hartung, Walter

    2005-01-01

    A system was developed at INFN Milano for preparing cesium telluride photo-cathodes and transferring them into an RF gun under ultra-high vacuum. This system has been in use at the Fermilab NICADD Photo-Injector Laboratory (FNPL) since 1997. A similar load-lock system is used at the TeSLA Test Facility at DESY-Hamburg. Two 1.625-cell high duty cycle RF guns have been fabricated for the project. Studies of the photo-emission and field emission ("dark current") behavior of both RF guns have been carried out. Unexpected phenomena were observed in one of the RF guns. In situ changes in the cathode's quantum efficiency and dark current with time were seen during operation of the photo-injector. These changes were correlated with the magnetostatic field at the cathode.* In addition, multipacting is observed in the RF guns under certain conditions. Recent measurements indicate a correlation between multipacting, anomalous photo-emission behavior, and anomalous field emission behavior. Results will be presented.

  18. Development of Low Parasitic Light Sensitivity and Low Dark Current 2.8 μm Global Shutter Pixel

    Directory of Open Access Journals (Sweden)

    Toshifumi Yokoyama

    2018-01-01

    Full Text Available Abstract: We developed a low parasitic light sensitivity (PLS and low dark current 2.8 μm global shutter pixel. We propose a new inner lens design concept to realize both low PLS and high quantum efficiency (QE. 1/PLS is 7700 and QE is 62% at a wavelength of 530 nm. We also propose a new storage-gate based memory node for low dark current. P-type implants and negative gate biasing are introduced to suppress dark current at the surface of the memory node. This memory node structure shows the world smallest dark current of 9.5 e−/s at 60 °C.

  19. Indirect dark matter searches: current status and perspectives

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Many theoretical ideas for the particle nature of dark matter exist. The  most popular models often predict that dark matter particles self-annihilate or decay, giving rise to potentially detectable signatures in astronomical observations.  I will summarize the current status of searches for such signatures and critically reassess recent claims for dark matter signals.  I will further provide an outlook on anticipated developments in the next 10 years, and discuss new methods to facilitate strategy development.

  20. Spectral response, dark current, and noise analyses in resonant tunneling quantum dot infrared photodetectors.

    Science.gov (United States)

    Jahromi, Hamed Dehdashti; Mahmoodi, Ali; Sheikhi, Mohammad Hossein; Zarifkar, Abbas

    2016-10-20

    Reduction of dark current at high-temperature operation is a great challenge in conventional quantum dot infrared photodetectors, as the rate of thermal excitations resulting in the dark current increases exponentially with temperature. A resonant tunneling barrier is the best candidate for suppression of dark current, enhancement in signal-to-noise ratio, and selective extraction of different wavelength response. In this paper, we use a physical model developed by the authors recently to design a proper resonant tunneling barrier for quantum infrared photodetectors and to study and analyze the spectral response of these devices. The calculated transmission coefficient of electrons by this model and its dependency on bias voltage are in agreement with experimental results. Furthermore, based on the calculated transmission coefficient, the dark current of a quantum dot infrared photodetector with a resonant tunneling barrier is calculated and compared with the experimental data. The validity of our model is proven through this comparison. Theoretical dark current by our model shows better agreement with the experimental data and is more accurate than the previously developed model. Moreover, noise in the device is calculated. Finally, the effect of different parameters, such as temperature, size of quantum dots, and bias voltage, on the performance of the device is simulated and studied.

  1. Hot spots and dark current in advanced plasma wakefield accelerators

    Directory of Open Access Journals (Sweden)

    G. G. Manahan

    2016-01-01

    Full Text Available Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  2. Gaas Displacement Damage Dosimeter Based on Diode Dark Currents

    Directory of Open Access Journals (Sweden)

    Warner Jeffrey H.

    2017-01-01

    Full Text Available GaAs diode dark currents are correlated over a very large proton energy range as a function of displacement damage dose (DDD. The linearity of the dark current increase with DDD over a wide range of applied voltage bias deems this device an excellent candidate for a displacement damage dosimeter. Additional proton testing performed in situ enabled error estimate determination to within 10% for simulated space use.

  3. Development of Low Parasitic Light Sensitivity and Low Dark Current 2.8 μm Global Shutter Pixel †

    Science.gov (United States)

    Yokoyama, Toshifumi; Tsutsui, Masafumi; Suzuki, Masakatsu; Nishi, Yoshiaki; Mizuno, Ikuo; Lahav, Assaf

    2018-01-01

    We developed a low parasitic light sensitivity (PLS) and low dark current 2.8 μm global shutter pixel. We propose a new inner lens design concept to realize both low PLS and high quantum efficiency (QE). 1/PLS is 7700 and QE is 62% at a wavelength of 530 nm. We also propose a new storage-gate based memory node for low dark current. P-type implants and negative gate biasing are introduced to suppress dark current at the surface of the memory node. This memory node structure shows the world smallest dark current of 9.5 e−/s at 60 °C. PMID:29370146

  4. Accounting for Dark Current Accumulated during Readout of Hubble's ACS/WFC Detectors

    Science.gov (United States)

    Ryon, Jenna E.; Grogin, Norman A.; Coe, Dan A.; ACS Team

    2018-06-01

    We investigate the properties of excess dark current accumulated during the 100-second full-frame readout of the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) detectors. This excess dark current, called "readout dark", gives rise to ambient background gradients and hot columns in each ACS/WFC image. While readout dark signal is removed from science images during the bias correction step in CALACS, the additional noise from the readout dark is currently not taken into account. We develop a method to estimate the readout dark noise properties in ACS/WFC observations. We update the error (ERR) extensions of superbias images to include the appropriate noise from the ambient readout dark gradient and stable hot columns. In recent data, this amounts to about 5 e-/pixel added variance in the rows farthest from the WFC serial registers, and about 7 to 30 e-/pixel added variance along the stable hot columns. We also flag unstable hot columns in the superbias data quality (DQ) extensions. The new reference file pipeline for ACS/WFC implements these updates to our superbias creation process.

  5. Probing the sign-changeable interaction between dark energy and dark matter with current observations

    Science.gov (United States)

    Guo, Juan-Juan; Zhang, Jing-Fei; Li, Yun-He; He, Dong-Ze; Zhang, Xin

    2018-03-01

    We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling b by the form b( a) = b 0 a+ b e(1- a), where at the early-time the coupling is given by a constant b e and today the coupling is described by another constant b 0. We explore six specific models with (i) Q = b( a) H 0 ρ 0, (ii) Q = b( a) H 0 ρ de, (iii) Q = b( a) H 0 ρ c, (iv) Q = b( a) Hρ 0, (v) Q = b( a) H ρ de, and (vi) Q = b( a) Hρ c. The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the Hubble constant direct measurement. We find that, for all the models, we have b 0 0 at around the 1 σ level, and b 0 and b e are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the 1 σ level, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.

  6. Dark Current Measurements in GIF++

    CERN Document Server

    Al-Qahtani, Abdulaziz

    2017-01-01

    This project revolved around creating a code that treats experiment files in order to fetch dark current measurements done for the Cathode Strip Chambers (CSC) exposed to long-term irradiation at Gamma Irradiation Facility (GIF++) and plot the results as functions of the accumulated charge. This paper will discuss the Compact Muon Solenoid (CMS) experiment, the CSCs that we have looked at (specifically the muon detectors located at the CMS endcaps), longevity test at GIF++, and finally discuss the code and results obtained.

  7. WIMP dark matter candidates and searches—current status and future prospects

    Science.gov (United States)

    Roszkowski, Leszek; Sessolo, Enrico Maria; Trojanowski, Sebastian

    2018-06-01

    We review several current aspects of dark matter theory and experiment. We overview the present experimental status, which includes current bounds and recent claims and hints of a possible signal in a wide range of experiments: direct detection in underground laboratories, gamma-ray, cosmic ray, x-ray, neutrino telescopes, and the LHC. We briefly review several possible particle candidates for a weakly interactive massive particle (WIMP) and dark matter that have recently been considered in the literature. We pay particular attention to the lightest neutralino of supersymmetry as it remains the best motivated candidate for dark matter and also shows excellent detection prospects. Finally we briefly review some alternative scenarios that can considerably alter properties and prospects for the detection of dark matter obtained within the standard thermal WIMP paradigm.

  8. WIMP dark matter candidates and searches-current status and future prospects.

    Science.gov (United States)

    Roszkowski, Leszek; Sessolo, Enrico Maria; Trojanowski, Sebastian

    2018-06-01

    We review several current aspects of dark matter theory and experiment. We overview the present experimental status, which includes current bounds and recent claims and hints of a possible signal in a wide range of experiments: direct detection in underground laboratories, gamma-ray, cosmic ray, x-ray, neutrino telescopes, and the LHC. We briefly review several possible particle candidates for a weakly interactive massive particle (WIMP) and dark matter that have recently been considered in the literature. We pay particular attention to the lightest neutralino of supersymmetry as it remains the best motivated candidate for dark matter and also shows excellent detection prospects. Finally we briefly review some alternative scenarios that can considerably alter properties and prospects for the detection of dark matter obtained within the standard thermal WIMP paradigm.

  9. Comparison of Measured Dark Current Distributions with Calculated Damage Energy Distributions in HgCdTe

    Science.gov (United States)

    Marshall, C. J.; Marshall, P. W.; Howe, C. L.; Reed, R. A.; Weller, R. A.; Mendenhall, M.; Waczynski, A.; Ladbury, R.; Jordan, T. M.

    2007-01-01

    This paper presents a combined Monte Carlo and analytic approach to the calculation of the pixel-to-pixel distribution of proton-induced damage in a HgCdTe sensor array and compares the results to measured dark current distributions after damage by 63 MeV protons. The moments of the Coulombic, nuclear elastic and nuclear inelastic damage distributions were extracted from Monte Carlo simulations and combined to form a damage distribution using the analytic techniques first described in [1]. The calculations show that the high energy recoils from the nuclear inelastic reactions (calculated using the Monte Carlo code MCNPX [2]) produce a pronounced skewing of the damage energy distribution. While the nuclear elastic component (also calculated using the MCNPX) contributes only a small fraction of the total nonionizing damage energy, its inclusion in the shape of the damage across the array is significant. The Coulombic contribution was calculated using MRED [3-5], a Geant4 [4,6] application. The comparison with the dark current distribution strongly suggests that mechanisms which are not linearly correlated with nonionizing damage produced according to collision kinematics are responsible for the observed dark current increases. This has important implications for the process of predicting the on-orbit dark current response of the HgCdTe sensor array.

  10. Identification of radiation induced dark current sources in pinned photodiode CMOS image sensors

    International Nuclear Information System (INIS)

    Goiffon, V.; Virmontois, C.; Magnan, P.; Cervantes, P.; Place, S.; Estribeau, M.; Martin-Gonthier, P.; Gaillardin, M.; Girard, S.; Paillet, P.

    2012-01-01

    This paper presents an investigation of Total Ionizing Dose (TID) induced dark current sources in Pinned Photodiodes (PPD) CMOS Image Sensors based on pixel design variations. The influence of several layout parameters is studied. Only one parameter is changed at a time enabling the direct evaluation of its contribution to the observed device degradation. By this approach, the origin of radiation induced dark current in PPD is localized on the pixel layout. The PPD peripheral shallow trench isolation does not seem to play a role in the degradation. The PPD area and a transfer gate contribution independent of the pixel dimensions appear to be the main sources of the TID induced dark current increase. This study also demonstrates that applying a negative voltage on the transfer gate during integration strongly reduces the radiation induced dark current. (authors)

  11. Exploring dark current voltage characteristics of micromorph silicon tandem cells with computer simulations

    NARCIS (Netherlands)

    Sturiale, A.; Li, H. B. T.; Rath, J.K.; Schropp, R.E.I.; Rubinelli, F.A.

    2009-01-01

    The transport mechanisms controlling the forward dark current-voltage characteristic of the silicon micromorph tandem solar cell were investigated with numerical modeling techniques. The dark current-voltage characteristics of the micromorph tandem structure at forward voltages show three regions:

  12. Analysis of surface dark current dependent upon surface passivation in APD based on GaAs

    International Nuclear Information System (INIS)

    Song, Hong Joo; Roh, Cheong Hyun; Lee, Jun Ho; Choi, Hong Goo; Hahn, Cheol-Koo; Kim, Dong Ho; Park, Jung Ho

    2009-01-01

    In this paper, we investigated the dependence of reverse dark current on two types of surface passivation, one of which is polyimide and the other is SiN x , for InAs quantum dots/GaAs separate absorption, charge, multiplication avalanche photodiode (SACM APD). From the experimental results, we found that dark current was dominated by surface current, and not bulk current. It was also noted that SiN x passivation has a surface current that is lower by three to nine times in magnitude than that in polyimide passivation in the whole range of bias. To analyze the difference in dark current due to the passivation types, we propose the theoretical current components. This shows that the dark current of both passivation types is mainly composed of generation–recombination (G–R) and tunneling components, originating from the surface. However, each component has a different magnitude for passivation types, which can be explained by carrier concentration and trap density. The dependence of dark current on temperature shows the different behaviors between passivation types and supports a theoretical description of current components

  13. High dark matter densities and the formation of extreme dwarf galaxies

    International Nuclear Information System (INIS)

    Lake, G.

    1990-01-01

    The extreme dwarfs of the Local Group, GR 8, Draco, and Ursa Minor have high densities of dark matter. If the dark matter is dissipationless, then there is a simple relation between the redshift of turnaround z(turn) and its current mean density. Three alternatives for the dSphs are discussed. If the dark matter follows the light, then z(turn) is greater than 30. If a density profile is adopted so that the mean density becomes low enough to be barely consistent with the standard density fluctuation spectrum of cold dark matter, then the mass-to-light ratios are greater than 1000 solar mass/solar luminosity. The last alternative is dissipational dark matter. In this case, the additional collapse factor owing to dissipation allows a later epoch of formation. 39 refs

  14. Dark currents and their effect on the primary beam in an X-band linac

    Directory of Open Access Journals (Sweden)

    Karl L. F. Bane

    2005-06-01

    Full Text Available We numerically study properties of primary dark currents in an X-band accelerating structure. For the H60VG3 structure considered for the Next Linear Collider (NLC we first perform a fairly complete (with some approximations calculation of dark-current trajectories. These results are used to study properties of the dark current leaving the structure. For example, at accelerating gradient of 65  MV/m, considering two very different assumptions about dark-current emission around the irises, we find that the fraction of emitted current leaving the structure to be a consistent ∼1%. Considering that ∼1  mA outgoing dark current is seen in measurement, this implies that ∼100  mA (or 10 pC per period is emitted within the structure itself. Using the formalism of the Liénard-Wiechert potentials, we then perform a systematic calculation of the transverse kick of dark currents on a primary linac bunch. The result is ∼1   V kick per mA (or per 0.1  pC per period dark current emitted from an iris. For an entire structure we estimate the total kick on a primary bunch to be ∼15   V. For the NLC linac this translates to a ratio of (final vertical beam offset to beam size of about 0.2. However, with the assumptions that needed to be made—particularly the number of emitters and their distribution within a structure—the accuracy of this result may be limited to the order of magnitude.

  15. Low dark current p-on-n technology for space applications

    Science.gov (United States)

    Péré-Laperne, N.; Baier, N.; Cervera, C.; Santailler, J. L.; Lobre, C.; Cassillo, C.; Berthoz, J.; Destefanis, V.; Sam Giao, D.; Lamoure, A.

    2017-08-01

    Space applications are requiring low dark current in the long wave infrared at low operating temperature for low flux observation. The applications envisioned with this type of specification are namely scientific and planetary missions. Within the framework of the joint laboratory between Sofradir and the CEA-LETI, a specific development of a TV format focal plane array with a cut-off wavelength of 12.5μm at 40K has been carried out. For this application, the p on n technology has been used. It is based on an In doped HgCdTe absorbing material grown by Liquid Phase Epitaxy (LPE) and an As implanted junction area. This architecture allows decreasing both dark current and series resistance compared to the legacy n on p technology based on Hg vacancies. In this paper, the technological improvements are briefly described. These technological tunings led to a 35% decrease of dark current in the diffusion regime. CEA-LETI and Sofradir demonstrated the ability to use the p on n technology with a long cutoff wavelength in the infrared range.

  16. High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu [Syracuse Univ., NY (United States)

    2016-01-01

    Direct dark matter detection experiments usually have excellent capability to distinguish nuclear recoils, expected interactions with Weakly Interacting Massive Particle (WIMP) dark matter, and electronic recoils, so that they can efficiently reject background events such as gamma-rays and charged particles. However, both WIMPs and neutrons can induce nuclear recoils. Neutrons are then the most crucial background for direct dark matter detection. It is important to understand and account for all sources of neutron backgrounds when claiming a discovery of dark matter detection or reporting limits on the WIMP-nucleon cross section. One type of neutron background that is not well understood is the cosmogenic neutrons from muons interacting with the underground cavern rock and materials surrounding a dark matter detector. The Neutron Multiplicity Meter (NMM) is a water Cherenkov detector capable of measuring the cosmogenic neutron flux at the Soudan Underground Laboratory, which has an overburden of 2090 meters water equivalent. The NMM consists of two 2.2-tonne gadolinium-doped water tanks situated atop a 20-tonne lead target. It detects a high-energy (>~ 50 MeV) neutron via moderation and capture of the multiple secondary neutrons released when the former interacts in the lead target. The multiplicity of secondary neutrons for the high-energy neutron provides a benchmark for comparison to the current Monte Carlo predictions. Combining with the Monte Carlo simulation, the muon-induced high-energy neutron flux above 50 MeV is measured to be (1.3 ± 0.2) ~ 10-9 cm-2s-1, in reasonable agreement with the model prediction. The measured multiplicity spectrum agrees well with that of Monte Carlo simulation for multiplicity below 10, but shows an excess of approximately a factor of three over Monte Carlo prediction for multiplicities ~ 10 - 20. In an effort to reduce neutron backgrounds for the dark matter experiment SuperCDMS SNO- LAB, an active neutron veto was developed

  17. Modeling the dark current histogram induced by gold contamination in complementary-metal-oxide-semiconductor image sensors

    Energy Technology Data Exchange (ETDEWEB)

    Domengie, F., E-mail: florian.domengie@st.com; Morin, P. [STMicroelectronics Crolles 2 (SAS), 850 Rue Jean Monnet, 38926 Crolles Cedex (France); Bauza, D. [CNRS, IMEP-LAHC - Grenoble INP, Minatec: 3, rue Parvis Louis Néel, CS 50257, 38016 Grenoble Cedex 1 (France)

    2015-07-14

    We propose a model for dark current induced by metallic contamination in a CMOS image sensor. Based on Shockley-Read-Hall kinetics, the expression of dark current proposed accounts for the electric field enhanced emission factor due to the Poole-Frenkel barrier lowering and phonon-assisted tunneling mechanisms. To that aim, we considered the distribution of the electric field magnitude and metal atoms in the depth of the pixel. Poisson statistics were used to estimate the random distribution of metal atoms in each pixel for a given contamination dose. Then, we performed a Monte-Carlo-based simulation for each pixel to set the number of metal atoms the pixel contained and the enhancement factor each atom underwent, and obtained a histogram of the number of pixels versus dark current for the full sensor. Excellent agreement with the dark current histogram measured on an ion-implanted gold-contaminated imager has been achieved, in particular, for the description of the distribution tails due to the pixel regions in which the contaminant atoms undergo a large electric field. The agreement remains very good when increasing the temperature by 15 °C. We demonstrated that the amplification of the dark current generated for the typical electric fields encountered in the CMOS image sensors, which depends on the nature of the metal contaminant, may become very large at high electric field. The electron and hole emissions and the resulting enhancement factor are described as a function of the trap characteristics, electric field, and temperature.

  18. Current constraints on interacting holographic dark energy

    International Nuclear Information System (INIS)

    Wu Qiang; Gong Yungui; Wang Anzhong; Alcaniz, J.S.

    2008-01-01

    Although there is mounting observational evidence that the cosmic expansion is undergoing a late-time acceleration, the physical mechanism behind such a phenomenon is yet unknown. In this Letter, we investigate a holographic dark energy (HDE) model with interaction between the components of the dark sector in the light of current cosmological observations. We use both the new gold sample of 182 type Ia supernovae (SNe Ia) and the 192 SNe Ia ESSENCE data, the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey and the shift parameter from the three-year Wilkinson Microwave Anisotropy Probe data. In agreement with previous results, we show that these observations suggest a very weak coupling or even a noninteracting HDE. The phantom crossing behavior in the context of these scenarios is also briefly discussed

  19. Low dark current InGaAs detector arrays for night vision and astronomy

    Science.gov (United States)

    MacDougal, Michael; Geske, Jon; Wang, Chad; Liao, Shirong; Getty, Jonathan; Holmes, Alan

    2009-05-01

    Aerius Photonics has developed large InGaAs arrays (1K x 1K and greater) with low dark currents for use in night vision applications in the SWIR regime. Aerius will present results of experiments to reduce the dark current density of their InGaAs detector arrays. By varying device designs and passivations, Aerius has achieved a dark current density below 1.0 nA/cm2 at 280K on small-pixel, detector arrays. Data is shown for both test structures and focal plane arrays. In addition, data from cryogenically cooled InGaAs arrays will be shown for astronomy applications.

  20. Dark currents for CEBAF linacs

    International Nuclear Information System (INIS)

    Yunn, B.C.

    1995-01-01

    Continuing on our numerical study of field emitted electrons from a superconducting CEBAF cavity we have identified all possible emission sites, magnitudes, and the energy profile of dark currents expected at CEBAF under nominal operating conditions. We find that most electrons do not survive beyond a single cryomodule which includes eight 5-cell superconducting cavities. However, some electrons can be accelerated through many cryomodules, ending up with an energy close to 100 MeV. However, no field emitted electrons can be recirculated along with an electron beam generated at the gun, due to the limited energy acceptance of CEBAF recirculation arcs. 4 refs., 4 figs

  1. SU-E-T-66: Characterization of Radiation Dose Associated with Dark Currents During Beam Hold for Respiratory-Gated Electron Therapy

    International Nuclear Information System (INIS)

    Hessler, J; Gupta, N; Rong, Y; Weldon, M

    2014-01-01

    Purpose: The main objective of this study was to estimate the radiation dose contributed by dark currents associated with the respiratory-gated electron therapy during beam hold. The secondary aim was to determine clinical benefits of using respiratory-gated electron therapy for left-sided breast cancer patients with positive internal mammary nodes (IMN). Methods: Measurements of the dark current-induced dose in all electron modes were performed on multiple Siemens and Varian linear accelerators by manually simulating beam-hold during respiratory gating. Dose was quantified at the machine isocenter by comparing the collected charge to the known output for all energies ranging from 6 to 18 MeV for a 10cm × 10cm field at 100 SSD with appropriate solid-water buildup. Using the Eclipse treatment planning system, we compared the additional dose associated with dark current using gated electron fields to the dose uncertainties associated with matching gated photon fields and ungated electron fields. Dose uncertainties were seen as hot and cold spots along the match line of the fields. Results: The magnitude of the dose associated with dark current is highly correlated to the energy of the beam and the amount of time the beam is on hold. For lower energies (6–12 MeV), there was minimal dark current dose (0.1–1.3 cGy/min). Higher energies (15–18 MeV) showed measurable amount of doses. The dark current associated with the electron beam-hold varied between linear accelerator vendors and depended on dark current suppression and the age of the linear accelerator. Conclusion: For energies up to 12 MeV, the dose associated with the dark current for respiratorygated electron therapy was shown to be negligible, and therefore should be considered an option for treating IMN positive left-sided breast cancer patients. However, at higher energies the benefit of respiratory gating may be outweighed by dose due to the dark current

  2. UV detector based on InAlN/GaN-on-Si HEMT stack with photo-to-dark current ratio > 107

    Science.gov (United States)

    kumar, Sandeep; Pratiyush, Anamika Singh; Dolmanan, Surani B.; Tripathy, Sudhiranjan; Muralidharan, Rangarajan; Nath, Digbijoy N.

    2017-12-01

    We demonstrate an InAlN/GaN-on-Si high electron mobility transistor based UV detector with a photo-to-dark current ratio of >107. The Ti/Al/Ni/Au metal stack was evaporated and thermal annealed rapidly for Ohmic contacts to the 2D electron gas (2DEG) at the InAlN/GaN interface, while the channel + barrier was recess etched to a depth of 20 nm to pinch-off the 2DEG between Source-Drain pads. A spectral responsivity (SR) of 32.9 A/W at 367 nm was measured at 5 V. A very high photo-to-dark current ratio of >107 was measured at a bias of 20 V. The photo-to-dark current ratio at a fixed bias was found to be decreasing with an increase in the recess length of photodetectors. The fabricated devices were found to exhibit a UV-to-visible rejection ratio of >103 with a low dark current of < 32 pA at 5 V. Transient measurements showed rise and fall times in the range of 3-4 ms. The gain mechanism was investigated, and carrier lifetimes were estimated which matched well with those reported elsewhere.

  3. DarkSide search for dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T.; Alton, D.; Arisaka, K.; Back, H. O.; Beltrame, P.; Benziger, J.; Bonfini, G.; Brigatti, A.; Brodsky, J.; Bussino, S.; Cadonati, L.; Calaprice, F.; Candela, A.; Cao, H.; Cavalcante, P.; Chepurnov, A.; Chidzik, S.; Cocco, A. G.; Condon, C.; D' Angelo, D.; Davini, S.; Vincenzi, M. De; Haas, E. De; Derbin, A.; Pietro, G. Di; Dratchnev, I.; Durben, D.; Empl, A.; Etenko, A.; Fan, A.; Fiorillo, G.; Franco, D.; Fomenko, K.; Forster, G.; Gabriele, F.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Goretti, A.; Grandi, L.; Gromov, M.; Guan, M.; Guo, C.; Guray, G.; Hungerford, E. V.; Ianni, Al; Ianni, An; Joliet, C.; Kayunov, A.; Keeter, K.; Kendziora, C.; Kidner, S.; Klemmer, R.; Kobychev, V.; Koh, G.; Komor, M.; Korablev, D.; Korga, G.; Li, P.; Loer, B.; Lombardi, P.; Love, C.; Ludhova, L.; Luitz, S.; Lukyanchenko, L.; Lund, A.; Lung, K.; Ma, Y.; Machulin, I.; Mari, S.; Maricic, J.; Martoff, C. J.; Meregaglia, A.; Meroni, E.; Meyers, P.; Mohayai, T.; Montanari, D.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B.; Muratova, V.; Nelson, A.; Nemtzow, A.; Nurakhov, N.; Orsini, M.; Ortica, F.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Parsells, R.; Pelliccia, N.; Perasso, L.; Perasso, S.; Perfetto, F.; Pinsky, L.; Pocar, A.; Pordes, S.; Randle, K.; Ranucci, G.; Razeto, A.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Saggese, P.; Saldanha, R.; Salvo, C.; Sands, W.; Seigar, M.; Semenov, D.; Shields, E.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvarov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Thompson, J.; Tonazzo, A.; Unzhakov, E.; Vogelaar, R. B.; Wang, H.; Westerdale, S.; Wojcik, M.; Wright, A.; Xu, J.; Yang, C.; Zavatarelli, S.; Zehfus, M.; Zhong, W.; Zuzel, G.

    2013-11-22

    The DarkSide staged program utilizes a two-phase time projection chamber (TPC) with liquid argon as the target material for the scattering of dark matter particles. Efficient background reduction is achieved using low radioactivity underground argon as well as several experimental handles such as pulse shape, ratio of ionization over scintillation signal, 3D event reconstruction, and active neutron and muon vetos. The DarkSide-10 prototype detector has proven high scintillation light yield, which is a particularly important parameter as it sets the energy threshold for the pulse shape discrimination technique. The DarkSide-50 detector system, currently in commissioning phase at the Gran Sasso Underground Laboratory, will reach a sensitivity to dark matter spin-independent scattering cross section of 10-45 cm2 within 3 years of operation.

  4. Imaging Galactic Dark Matter with High-Energy Cosmic Neutrinos.

    Science.gov (United States)

    Argüelles, Carlos A; Kheirandish, Ali; Vincent, Aaron C

    2017-11-17

    We show that the high-energy cosmic neutrinos seen by the IceCube Neutrino Observatory can be used to probe interactions between neutrinos and the dark sector that cannot be reached by current cosmological methods. The origin of the observed neutrinos is still unknown, and their arrival directions are compatible with an isotropic distribution. This observation, together with dedicated studies of Galactic plane correlations, suggests a predominantly extragalactic origin. Interactions between this isotropic extragalactic flux and the dense dark matter (DM) bulge of the Milky Way would thus lead to an observable imprint on the distribution, which would be seen by IceCube as (i) slightly suppressed fluxes at energies below a PeV and (ii) a deficit of events in the direction of the Galactic center. We perform an extended unbinned likelihood analysis using the four-year high-energy starting event data set to constrain the strength of DM-neutrino interactions for two model classes. We find that, in spite of low statistics, IceCube can probe regions of the parameter space inaccessible to current cosmological methods.

  5. The Dark Cube: dark character profiles and OCEAN

    Directory of Open Access Journals (Sweden)

    Danilo Garcia

    2017-09-01

    Full Text Available Background The Big Five traits (i.e., openness, conscientiousness, extraversion, agreeableness, and neuroticism: OCEAN have been suggested to provide a meaningful taxonomy for studying the Dark Triad: Machiavellianism, narcissism, and psychopathy. Nevertheless, current research consists of mixed and inconsistent associations between the Dark Triad and OCEAN. Here we used the Dark Cube (Garcia & Rosenberg, 2016, a model of malevolent character theoretically based on Cloninger’s biopsychosocial model of personality and in the assumption of a ternary structure of malevolent character. We use the dark cube profiles to investigate differences in OCEAN between individuals who differ in one dark character trait while holding the other two constant (i.e., conditional relationships. Method Participants (N = 330 responded to the Short Dark Triad Inventory and the Big Five Inventory and were grouped according to the eight possible combinations using their dark trait scores (M, high Machiavellianism; m, low Machiavellianism; N, high narcissism; n, low narcissism; P, high psychopathy; p, low psychopathy: MNP “maleficent”, MNp “manipulative narcissistic”, MnP “anti-social”, Mnp “Machiavellian”, mNP “psychopathic narcissistic”, mNp “narcissistic”, mnP “psychopathic”, and mnp “benevolent”. Results High narcissism-high extraversion and high psychopathy-low agreeableness were consistently associated across comparisons. The rest of the comparisons showed a complex interaction. For example, high Machiavellianism-high neuroticism only when both narcissism and psychopathy were low (Mnp vs. mnp, high narcissism-high conscientiousness only when both Machiavellianism and psychopathy were also high (MNP vs. MnP, and high psychopathy-high neuroticism only when Machiavellianism was low and narcissism was high (mNP vs. mNp. Conclusions We suggest that the Dark Cube is a useful tool in the investigation of a consistent Dark Triad Theory

  6. The Dark Cube: dark character profiles and OCEAN.

    Science.gov (United States)

    Garcia, Danilo; González Moraga, Fernando R

    2017-01-01

    The Big Five traits (i.e., openness, conscientiousness, extraversion, agreeableness, and neuroticism: OCEAN) have been suggested to provide a meaningful taxonomy for studying the Dark Triad: Machiavellianism, narcissism, and psychopathy. Nevertheless, current research consists of mixed and inconsistent associations between the Dark Triad and OCEAN. Here we used the Dark Cube (Garcia & Rosenberg, 2016), a model of malevolent character theoretically based on Cloninger's biopsychosocial model of personality and in the assumption of a ternary structure of malevolent character. We use the dark cube profiles to investigate differences in OCEAN between individuals who differ in one dark character trait while holding the other two constant (i.e., conditional relationships). Participants ( N  = 330) responded to the Short Dark Triad Inventory and the Big Five Inventory and were grouped according to the eight possible combinations using their dark trait scores (M, high Machiavellianism; m, low Machiavellianism; N, high narcissism; n, low narcissism; P, high psychopathy; p, low psychopathy): MNP "maleficent", MNp "manipulative narcissistic", MnP "anti-social", Mnp "Machiavellian", mNP "psychopathic narcissistic", mNp "narcissistic", mnP "psychopathic", and mnp "benevolent". High narcissism-high extraversion and high psychopathy-low agreeableness were consistently associated across comparisons. The rest of the comparisons showed a complex interaction. For example, high Machiavellianism-high neuroticism only when both narcissism and psychopathy were low (Mnp vs. mnp), high narcissism-high conscientiousness only when both Machiavellianism and psychopathy were also high (MNP vs. MnP), and high psychopathy-high neuroticism only when Machiavellianism was low and narcissism was high (mNP vs. mNp). We suggest that the Dark Cube is a useful tool in the investigation of a consistent Dark Triad Theory. This approach suggests that the only clear relationships were narcissism

  7. Silicon Photomultipliers: Dark Current and its Statistical Spread

    Directory of Open Access Journals (Sweden)

    Roberto PAGANO

    2012-03-01

    Full Text Available Aim of this paper is to investigate on a statistical basis at the wafer level the relationship existing among the dark currents of the single pixel compared to the whole Silicon Photomultiplier array. This is the first time to our knowledge that such a comparison is made, crucial to pass this new technology to the semiconductor manufacturing standards. In particular, emission microscopy measurements and current measurements allowed us to conclude that optical trenches strongly improve the device performances.

  8. Progress of MCT Detector Technology at AIM Towards Smaller Pitch and Lower Dark Current

    Science.gov (United States)

    Eich, D.; Schirmacher, W.; Hanna, S.; Mahlein, K. M.; Fries, P.; Figgemeier, H.

    2017-09-01

    We present our latest results on cooled p-on- n planar mercury cadmium telluride (MCT) photodiode technology. Along with a reduction in dark current for raising the operating temperature ( T op), AIM INFRAROT-MODULE GmbH (AIM) has devoted its development efforts to shrinking the pixel size. Both are essential requirements to meet the market demands for reduced size, weight and power and high-operating temperature applications. Detectors based on the p-on- n technology developed at AIM now span the spectrum from the mid-wavelength infrared (MWIR) to the very long wavelength infrared (VLWIR) with cut-off wavelengths from 5 μm to about 13.5 μm at 80 K. The development of the p-on- n technology for VLWIR as well as for MWIR is mainly implemented in a planar photodetector design with a 20- μm pixel pitch. For the VLWIR, dark currents significantly reduced as compared to `Tennant's Rule 07' are demonstrated for operating temperatures between 30 K and 100 K. This allows for the same dark current performance at a 20 K higher operating temperature than with previous AIM technology. For MWIR detectors with a 20- μm pitch, noise equivalent temperature differences of less than 30 mK are obtained up to 170 K. This technology has been transferred to our small pixel pitch high resolution (XGA) MWIR detector with 1024 × 768 pixels at a 10- μm pitch. Excellent performance at an operating temperature of 160 K is demonstrated.

  9. DARKNESS: A Microwave Kinetic Inductance Detector Integral Field Spectrograph for High-contrast Astronomy

    Science.gov (United States)

    Meeker, Seth R.; Mazin, Benjamin A.; Walter, Alex B.; Strader, Paschal; Fruitwala, Neelay; Bockstiegel, Clint; Szypryt, Paul; Ulbricht, Gerhard; Coiffard, Grégoire; Bumble, Bruce; Cancelo, Gustavo; Zmuda, Ted; Treptow, Ken; Wilcer, Neal; Collura, Giulia; Dodkins, Rupert; Lipartito, Isabel; Zobrist, Nicholas; Bottom, Michael; Shelton, J. Chris; Mawet, Dimitri; van Eyken, Julian C.; Vasisht, Gautam; Serabyn, Eugene

    2018-06-01

    We present DARKNESS (the DARK-speckle Near-infrared Energy-resolving Superconducting Spectrophotometer), the first of several planned integral field spectrographs to use optical/near-infrared Microwave Kinetic Inductance Detectors (MKIDs) for high-contrast imaging. The photon counting and simultaneous low-resolution spectroscopy provided by MKIDs will enable real-time speckle control techniques and post-processing speckle suppression at frame rates capable of resolving the atmospheric speckles that currently limit high-contrast imaging from the ground. DARKNESS is now operational behind the PALM-3000 extreme adaptive optics system and the Stellar Double Coronagraph at Palomar Observatory. Here, we describe the motivation, design, and characterization of the instrument, early on-sky results, and future prospects.

  10. Dark current spectroscopy of space and nuclear environment induced displacement damage defects in pinned photodiode based CMOS image sensors

    International Nuclear Information System (INIS)

    Belloir, Jean-Marc

    2016-01-01

    CMOS image sensors are envisioned for an increasing number of high-end scientific imaging applications such as space imaging or nuclear experiments. Indeed, the performance of high-end CMOS image sensors has dramatically increased in the past years thanks to the unceasing improvements of microelectronics, and these image sensors have substantial advantages over CCDs which make them great candidates to replace CCDs in future space missions. However, in space and nuclear environments, CMOS image sensors must face harsh radiation which can rapidly degrade their electro-optical performances. In particular, the protons, electrons and ions travelling in space or the fusion neutrons from nuclear experiments can displace silicon atoms in the pixels and break the crystalline structure. These displacement damage effects lead to the formation of stable defects and to the introduction of states in the forbidden bandgap of silicon, which can allow the thermal generation of electron-hole pairs. Consequently, non ionizing radiation leads to a permanent increase of the dark current of the pixels and thus a decrease of the image sensor sensitivity and dynamic range. The aim of the present work is to extend the understanding of the effect of displacement damage on the dark current increase of CMOS image sensors. In particular, this work focuses on the shape of the dark current distribution depending on the particle type, energy and fluence but also on the image sensor physical parameters. Thanks to the many conditions tested, an empirical model for the prediction of the dark current distribution induced by displacement damage in nuclear or space environments is experimentally validated and physically justified. Another central part of this work consists in using the dark current spectroscopy technique for the first time on irradiated CMOS image sensors to detect and characterize radiation-induced silicon bulk defects. Many types of defects are detected and two of them are identified

  11. Observation of dark pulses in 10 nm thick YBCO nanostrips presenting hysteretic current voltage characteristics

    Science.gov (United States)

    Ejrnaes, M.; Parlato, L.; Arpaia, R.; Bauch, T.; Lombardi, F.; Cristiano, R.; Tafuri, F.; Pepe, G. P.

    2017-12-01

    We have fabricated several 10 nm thick and 65 nm wide YBa2Cu3O7-δ (YBCO) nanostrips. The nanostrips with the highest critical current densities are characterized by hysteretic current voltage characteristics (IVCs) with a direct bistable switch from the zero-voltage to the finite voltage state. The presence of hysteretic IVCs allowed the observation of dark pulses due to fluctuations phenomena. The key role of the bistable behavior is its ability to transform a small disturbance (e.g. an intrinsic fluctuation) into a measurable transient signal, i.e. a dark pulse. On the contrary, in devices characterized by lower critical current density values, the IVCs are non-hysteretic and dark pulses have not been observed. To investigate the physical origin of the dark pulses, we have measured the bias current dependence of the dark pulse rate: the observed exponential increase with the bias current is compatible with mechanisms based on thermal activation of magnetic vortices in the nanostrip. We believe that the successful amplification of small fluctuation events into measurable signals in nanostrips of ultrathin YBCO is a milestone for further investigation of YBCO nanostrips for superconducting nanostrip single photon detectors and other quantum detectors for operation at higher temperatures.

  12. Figure of merit for dark energy constraints from current observational data

    International Nuclear Information System (INIS)

    Wang Yun

    2008-01-01

    In order to make useful comparisons of different dark energy experiments, it is important to choose the appropriate figure of merit (FoM) for dark energy constraints. Here we show that for a set of dark energy parameters (f i ), it is most intuitive to define FoM=1/√(detCov(f 1 ,f 2 ,f 3 ,...)), where Cov(f 1 ,f 2 ,f 3 ,...) is the covariance matrix of (f i ). In order for this FoM to represent the dark energy constraints in an optimal manner, the dark energy parameters (f i ) should have clear physical meaning and be minimally correlated. We demonstrate two useful choices of (f i ) using 182 SNe Ia (from the HST/GOODS program, the first year Supernova Legacy Survey, and nearby SN Ia surveys), [R(z * ),l a (z * ),Ω b h 2 ] from the five year Wilkinson Microwave Anisotropy Probe observations, and Sloan Digital Sky Survey measurement of the baryon acoustic oscillation scale, assuming the Hubble Space Telescope prior of H 0 =72±8 (km/s) Mpc -1 , and without assuming spatial flatness. We find that for a dark energy equation of state linear in the cosmic scale factor a, the correlation of (w 0 ,w 0.5 ) [w 0 =w X (z=0), w 0.5 =w X (z=0.5), with w X (a)=3w 0.5 -2w 0 +3(w 0 -w 0.5 )a] is significantly smaller than that of (w 0 ,w a ) [with w X (a)=w 0 +(1-a)w a ]. In order to obtain model-independent constraints on dark energy, we parametrize the dark energy density function X(z)=ρ X (z)/ρ X (0) as a free function with X 0.5 , X 1.0 , and X 1.5 [values of X(z) at z=0.5, 1.0, and 1.5] as free parameters estimated from data. If one assumes a linear dark energy equation of state, current observational data are consistent with a cosmological constant at 68% C.L. If one assumes X(z) to be a free function parametrized by (X 0.5 ,X 1.0 ,X 1.5 ), current data deviate from a cosmological constant at z=1 at 68% C.L., but are consistent with a cosmological constant at 95% C.L. Future dark energy experiments will allow us to dramatically increase the FoM of constraints on (w 0

  13. Probing the stability of superheavy dark matter particles with high-energy neutrinos

    International Nuclear Information System (INIS)

    Esmaili, Arman; Peres, O.L.G.

    2012-01-01

    Full text: There is currently mounting evidence for the existence of dark matter in our Universe from various astrophysical and cosmological observations, but the two of the most fundamental properties of the dark matter particle, the mass and the lifetime, are only weakly constrained by the astronomical and cosmological evidence of dark matter. We derive lower limits on the lifetime of dark matter particles with masses in the range 10 TeV - 10 18 GeV from the non-observation of ultrahigh energy neutrinos in the AMANDA, IceCube, Auger and ANITA experiments. All these experiments probe different energy windows and perfectly complement each other. For dark matter particles which produce neutrinos in a two body or a three body decay, we find that the dark matter lifetime must be longer than ∼ 10 26 s for masses between 10 TeV and the Grand Unification scale. We will consider various scenarios where the decay of the dark matter particle produces high energy neutrinos. Neutrinos travel in the Universe without suffering an appreciable attenuation, even for EeV neutrinos, in contrast to photons which rapidly lose their energy via pair production. This remarkable property makes neutrinos a very suitable messenger to constrain the lifetime of superheavy dark matter particles. Finally, we also calculate, for concrete particle physics scenarios, the limits on the strength of the interactions that induce the dark matter decay. (author)

  14. Coupled dark matter-dark energy in light of near universe observations

    International Nuclear Information System (INIS)

    Honorez, Laura Lopez; Reid, Beth A.; Verde, Licia; Jimenez, Raul; Mena, Olga

    2010-01-01

    Cosmological analysis based on currently available observations are unable to rule out a sizeable coupling among the dark energy and dark matter fluids. We explore a variety of coupled dark matter-dark energy models, which satisfy cosmic microwave background constraints, in light of low redshift and near universe observations. We illustrate the phenomenology of different classes of dark coupling models, paying particular attention in distinguishing between effects that appear only on the expansion history and those that appear in the growth of structure. We find that while a broad class of dark coupling models are effectively models where general relativity (GR) is modified — and thus can be probed by a combination of tests for the expansion history and the growth of structure —, there is a class of dark coupling models where gravity is still GR, but the growth of perturbations is, in principle modified. While this effect is small in the specific models we have considered, one should bear in mind that an inconsistency between reconstructed expansion history and growth may not uniquely indicate deviations from GR. Our low redshift constraints arise from cosmic velocities, redshift space distortions and dark matter abundance in galaxy voids. We find that current data constrain the dimensionless coupling to be |ξ| < 0.2, but prospects from forthcoming data are for a significant improvement. Future, precise measurements of the Hubble constant, combined with high-precision constraints on the growth of structure, could provide the key to rule out dark coupling models which survive other tests. We shall exploit as well weak equivalence principle violation arguments, which have the potential to highly disfavour a broad family of coupled models

  15. Trapping and dark current in plasma-based accelerators

    International Nuclear Information System (INIS)

    Schroder, C.B.; Esarey, E.; Shadwick, B.A.; Leemans, W.P.

    2004-01-01

    The trapping of thermal electrons in a nonlinear plasma wave of arbitrary phase velocity is investigated. The threshold plasma wave amplitude for trapping plasma electrons is calculated, thereby determining the fraction trapped and the expected dark current in a plasma-based accelerator. It is shown that the presence of a laser field (e.g., trapping in the self-modulated regime of the laser wakefield accelerator) increases the trapping threshold. Implications for experimental and numerical laser-plasma studies are discussed

  16. Higgsino dark matter in high-scale supersymmetry

    International Nuclear Information System (INIS)

    Nagata, Natsumi

    2014-11-01

    We study a supersymmetric (SUSY) Standard Model in which a Higgsino is light enough to be dark matter, while the other SUSY particles are much heavier than the weak scale. We carefully treat the effects of heavy SUSY particles to the Higgsino nature, especially taking into account the renormalization effects due to the large hierarchy between the Higgsino and the SUSY breaking scales. Inelastic scattering of the Higgsino dark matter with a nucleus is studied, and the constraints on the scattering by the direct detection experiments are discussed. This gives an upper limit on the new physics scale. Bounds on the dark matter-nucleon elastic scattering, the electric dipole moments, and direct production of Higgsinos, on the other hand, give a lower limit. We show the current status on the limits and discuss the future prospects.

  17. Dark current, breakdown, and magnetic field effects in a multicell, 805 MHz cavity

    Directory of Open Access Journals (Sweden)

    J. Norem

    2003-07-01

    Full Text Available We present measurements of dark currents and x rays in a six cell 805 MHz cavity, taken as part of an rf development program for muon cooling, which requires high power, high stored energy, low frequency cavities operating in a strong magnetic field. We have done the first systematic study of the behavior of high power rf in a strong (2.5–4 T magnetic field. Our measurements extend over a very large dynamic range in current and provide good fits to the Fowler-Nordheim field emission model assuming mechanical structures produce field enhancements at the surface. The locally enhanced field intensities we derive at the tips of these emitters are very large, (∼10  GV/m, and should produce tensile stresses comparable to the tensile strength of the copper cavity walls and should be capable of causing breakdown events. We also compare our data with estimates of tensile stresses from a variety of accelerating structures. Preliminary studies of the internal surface of the cavity and window are presented, which show splashes of copper with many sharp cone shaped protrusions and wires which can explain the experimentally measured field enhancements. We discuss a “cold copper” breakdown mechanism and briefly review alternatives. We also discuss a number of effects due to the 2.5 T solenoidal fields on the cavity such as altered field emission due to mechanical deformation of emitters, and dark current ring beams, which are produced from the irises by E×B drifts during the nonrelativistic part of the acceleration process.

  18. Origin of large dark current increase in InGaAs/InP avalanche photodiode

    Science.gov (United States)

    Wen, J.; Wang, W. J.; Chen, X. R.; Li, N.; Chen, X. S.; Lu, W.

    2018-04-01

    The large dark current increase near the breakdown voltage of an InGaAs/InP avalanche photodiode is observed and analyzed from the aspect of bulk defects in the device materials. The trap level information is extracted from the temperature-dependent electrical characteristics of the device and the low temperature photoluminescence spectrum of the materials. Simulation results with the extracted trap level taken into consideration show that the trap is in the InP multiplication layer and the trap assisted tunneling current induced by the trap is the main cause of the large dark current increase with the bias from the punch-through voltage to 95% breakdown voltage.

  19. Turning off the lights: How dark is dark matter?

    International Nuclear Information System (INIS)

    McDermott, Samuel D.; Yu Haibo; Zurek, Kathryn M.

    2011-01-01

    We consider current observational constraints on the electromagnetic charge of dark matter. The velocity dependence of the scattering cross section through the photon gives rise to qualitatively different constraints than standard dark matter scattering through massive force carriers. In particular, recombination epoch observations of dark matter density perturbations require that ε, the ratio of the dark matter to electronic charge, is less than 10 -6 for m X =1 GeV, rising to ε -4 for m X =10 TeV. Though naively one would expect that dark matter carrying a charge well below this constraint could still give rise to large scattering in current direct detection experiments, we show that charged dark matter particles that could be detected with upcoming experiments are expected to be evacuated from the Galactic disk by the Galactic magnetic fields and supernova shock waves and hence will not give rise to a signal. Thus dark matter with a small charge is likely not a source of a signal in current or upcoming dark matter direct detection experiments.

  20. Dark current and radiation shielding studies for the ILC main linac

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, Nikolai V. [Fermilab; Rakhno, I. L. [Fermilab; Solyak, N. A. [Fermilab; Sukhanov, A. [Fermilab; Tropin, I. S. [Fermilab

    2016-12-05

    Electrons of dark current (DC), generated in high-gradient superconducting RF cavities (SRF) due to field emission, can be accelerated up to very high energies—19 GeV in the case of the International Linear Collider (ILC) main linac—before they are removed by focusing and steering magnets. Electromagnetic and hadron showers generated by such electrons can represent a significant radiation threat to the linac equipment and personnel. In our study, an operational scenario is analysed which is believed can be considered as the worst case scenario for the main linac regarding the DC contribution to the radiation environment in the main linac tunnel. A detailed modelling is performed for the DC electrons which are emitted from the surface of the SRF cavities and can be repeatedly accelerated in the high-gradient fields in many SRF cavities. Results of MARS15 Monte Carlo calculations, performed for the current main linac tunnel design, reveal that the prompt dose design level of 25 μSv/hr in the service tunnel can be provided by a 2.3-m thick concrete wall between the main and service ls.

  1. Modeling of the quantum dot filling and the dark current of quantum dot infrared photodetectors

    International Nuclear Information System (INIS)

    Ameen, Tarek A.; El-Batawy, Yasser M.; Abouelsaood, A. A.

    2014-01-01

    A generalized drift-diffusion model for the calculation of both the quantum dot filling profile and the dark current of quantum dot infrared photodetectors is proposed. The confined electrons inside the quantum dots produce a space-charge potential barrier between the two contacts, which controls the quantum dot filling and limits the dark current in the device. The results of the model reasonably agree with a published experimental work. It is found that increasing either the doping level or the temperature results in an exponential increase of the dark current. The quantum dot filling turns out to be nonuniform, with a dot near the contacts containing more electrons than one in the middle of the device where the dot occupation approximately equals the number of doping atoms per dot, which means that quantum dots away from contacts will be nearly unoccupied if the active region is undoped

  2. The dark universe dark matter and dark energy

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    According to the standard cosmological model, 95% of the present mass density of the universe is dark: roughly 70% of the total in the form of dark energy and 25% in the form of dark matter. In a series of four lectures, I will begin by presenting a brief review of cosmology, and then I will review the observational evidence for dark matter and dark energy. I will discuss some of the proposals for dark matter and dark energy, and connect them to high-energy physics. I will also present an overview of an observational program to quantify the properties of dark energy.

  3. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    Science.gov (United States)

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique.

  4. Ultra-Low Dark Current HgCdTe Detector in SWIR for Space Applications

    Science.gov (United States)

    Cervera, C.; Boulade, O.; Gravrand, O.; Lobre, C.; Guellec, F.; Sanson, E.; Ballet, P.; Santailler, J. L.; Moreau, V.; Zanatta, J. P.; Fieque, B.; Castelein, P.

    2017-10-01

    This paper presents recent developments at Commissariat à l'Energie atomique, Laboratoire d'Electronique et de Technologie de l'Information infrared laboratory on processing and characterization of p-on- n HgCdTe (MCT) planar infrared focal plane arrays (FPAs) in short-wave infrared (SWIR) spectral band for the astrophysics applications. These FPAs have been grown using both liquid phase epitaxy and molecular beam epitaxy on a lattice-matched CdZnTe substrate. This technology exhibits lower dark current and lower series resistance in comparison with n-on- p vacancy-doped architecture and is well adapted for low flux detection or high operating temperature. This architecture has been evaluated for space applications in long-wave infrared and very-long-wave infrared spectral bands with cut-off wavelengths from 10 μm up to 17 μm at 78 K and is now evaluated for the SWIR range. The metallurgical nature of the absorbing layer is also examined and both molecular beam epitaxy and liquid phase epitaxy have been investigated. Electro-optical characterizations have been performed on individual photodiodes from test arrays, whereas dark current investigation has been performed with a fully functional readout integrated circuit dedicated to low flux operations.

  5. Quantum Field Theory of Interacting Dark Matter/Dark Energy: Dark Monodromies

    CERN Document Server

    D'Amico, Guido; Kaloper, Nemanja

    2016-11-28

    We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled. However, if dark energy and a fraction of dark matter are very light axions, they can have significant mixings which are radiatively stable and perfectly consistent with quantum field theory. Such models can naturally occur in multi-axion realizations of monodromies. The mixings yield interesting signatures which are observable and are within current cosmological limits but could be constrained further by future observations.

  6. Influence of Different Surface Modifications on the Photovoltaic Performance and Dark Current of Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    XU Weiwei; DAI Songyuan; HU Linhua; ZHANG Changneng; XIAO Shangfeng; LUO Xiangdong; JING Weiping; WANG Kongjia

    2007-01-01

    The TiO2 nanoporous film photoelectrode, as a crucial component of dye-sensitized solar cells, has been investigated. The photovoltaic properties and the dark current were studied by two surface modification methods. One was to apply a compact layer between the conductive glass substrate and nanoporous TiO2 film. Another was to produce TiO2 nanoparticles among the microstructure by TiCU treatment. A suitable concentration and number of times for TiCU treatment were found in our experiment. The dark current is suppressed by surface modifications, leading to a significant improvement in the solar cells performance. An excessive concentration of TiCU will produce more surface states and introduce a larger dark current reversely. The dye is also regarded as a source of charge recombination in dark to some extent, due to an amount of surface protonations introduced by the interfacial link in the conductive glass substrate/dye interface and dye/TiO2 interface.

  7. Barrier lowering effect and dark current characteristics in asymmetric GaAs/AlGaAs multi quantum well structure

    Energy Technology Data Exchange (ETDEWEB)

    Altin, E. [Inonu University, Scientific and Technological Research Center, Malatya (Turkey); Anadolu University, Department of Physics, Eskisehir (Turkey); Hostut, M. [Akdeniz University, Department of Secondary Education of Science and Maths., Division of Physics Education, Antalya (Turkey); Ergun, Y. [Anadolu University, Department of Physics, Eskisehir (Turkey)

    2011-12-15

    In this study, we investigate dark current voltage characteristics of GaAs/AlGaAs staircase-like asymmetric multiquantum well structure at various temperatures experimentally. The activation energy is calculated by using Arrhenius plots at different voltages. It is found that the activation energy decreased with increasing electric field. This result is evaluated using a barrier lowering effect which is a combination of geometrical and Poole-Frenkel effects. Measured dark current density-voltage (J-V) characteristics compared with the Levine model, 3D carrier drift model and the emission capture model. The best agreement with the experimental results of dark current densities is obtained by the Levine model. (orig.)

  8. Cold dark matter plus not-so-clumpy dark relics

    NARCIS (Netherlands)

    Diamanti, R.; Ando, S.; Gariazzo, S.; Mena, O.; Weniger, C.

    Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark

  9. Dark matter phenomenology of high-speed galaxy cluster collisions

    International Nuclear Information System (INIS)

    Mishchenko, Yuriy; Ji, Chueng-Ryong

    2017-01-01

    We perform a general computational analysis of possible post-collision mass distributions in high-speed galaxy cluster collisions in the presence of self-interacting dark matter. Using this analysis, we show that astrophysically weakly self-interacting dark matter can impart subtle yet measurable features in the mass distributions of colliding galaxy clusters even without significant disruptions to the dark matter halos of the colliding galaxy clusters themselves. Most profound such evidence is found to reside in the tails of dark matter halos' distributions, in the space between the colliding galaxy clusters. Such features appear in our simulations as shells of scattered dark matter expanding in alignment with the outgoing original galaxy clusters, contributing significant densities to projected mass distributions at large distances from collision centers and large scattering angles of up to 90 "c"i"r"c"l"e. Our simulations indicate that as much as 20% of the total collision's mass may be deposited into such structures without noticeable disruptions to the main galaxy clusters. Such structures at large scattering angles are forbidden in purely gravitational high-speed galaxy cluster collisions. Convincing identification of such structures in real colliding galaxy clusters would be a clear indication of the self-interacting nature of dark matter. Our findings may offer an explanation for the ring-like dark matter feature recently identified in the long-range reconstructions of the mass distribution of the colliding galaxy cluster CL0024+017. (orig.)

  10. Dark matter phenomenology of high-speed galaxy cluster collisions

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Yuriy [Izmir University of Economics, Faculty of Engineering, Izmir (Turkey); Ji, Chueng-Ryong [North Carolina State University, Department of Physics, Raleigh, NC (United States)

    2017-08-15

    We perform a general computational analysis of possible post-collision mass distributions in high-speed galaxy cluster collisions in the presence of self-interacting dark matter. Using this analysis, we show that astrophysically weakly self-interacting dark matter can impart subtle yet measurable features in the mass distributions of colliding galaxy clusters even without significant disruptions to the dark matter halos of the colliding galaxy clusters themselves. Most profound such evidence is found to reside in the tails of dark matter halos' distributions, in the space between the colliding galaxy clusters. Such features appear in our simulations as shells of scattered dark matter expanding in alignment with the outgoing original galaxy clusters, contributing significant densities to projected mass distributions at large distances from collision centers and large scattering angles of up to 90 {sup circle}. Our simulations indicate that as much as 20% of the total collision's mass may be deposited into such structures without noticeable disruptions to the main galaxy clusters. Such structures at large scattering angles are forbidden in purely gravitational high-speed galaxy cluster collisions. Convincing identification of such structures in real colliding galaxy clusters would be a clear indication of the self-interacting nature of dark matter. Our findings may offer an explanation for the ring-like dark matter feature recently identified in the long-range reconstructions of the mass distribution of the colliding galaxy cluster CL0024+017. (orig.)

  11. Analysis of dark current images of a CMOS camera during gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Náfrádi, Gábor, E-mail: nafradi@reak.bme.hu [INT, BME, EURATOM Association, H-1111 Budapest (Hungary); Czifrus, Szabolcs, E-mail: czifrus@reak.bme.hu [INT, BME, EURATOM Association, H-1111 Budapest (Hungary); Kocsis, Gábor, E-mail: kocsis.gabor@wigner.mta.hu [Wigner RCP, RMI, EURATOM Association, POB 49, 1525 Budapest (Hungary); Pór, Gábor, E-mail: por@reak.bme.hu [INT, BME, EURATOM Association, H-1111 Budapest (Hungary); Szepesi, Tamás, E-mail: szepesi.tamas@wigner.mta.hu [Wigner RCP, RMI, EURATOM Association, POB 49, 1525 Budapest (Hungary); Zoletnik, Sándor, E-mail: zoletnik.sandor@wigner.mta.hu [Wigner RCP, RMI, EURATOM Association, POB 49, 1525 Budapest (Hungary)

    2013-12-15

    Highlights: • Radiation tolerance of a fast framing CMOS camera EDICAM examined. • We estimate the expected gamma dose and spectrum of EDICAM with MCNP. • We irradiate EDICAM by 23.5 Gy in 70 min in a fission rector. • Dose rate normalised average brightness of frames grows linearly with the dose. • Dose normalised average brightness of frames follows the dose rate time evolution. -- Abstract: We report on the behaviour of the dark current images of the Event Detection Intelligent Camera (EDICAM) when placed into an irradiation field of gamma rays. EDICAM is an intelligent fast framing CMOS camera operating in the visible spectral range, which is designed for the video diagnostic system of the Wendelstein 7-X (W7-X) stellarator. Monte Carlo calculations were carried out in order to estimate the expected gamma spectrum and dose for an entire year of operation in W7-X. EDICAM was irradiated in a pure gamma field in the Training Reactor of BME with a dose of approximately 23.5 Gy in 1.16 h. During the irradiation, numerous frame series were taken with the camera with exposure times 20 μs, 50 μs, 100 μs, 1 ms, 10 ms, 100 ms. EDICAM withstood the irradiation, but suffered some dynamic range degradation. The behaviour of the dark current images during irradiation is described in detail. We found that the average brightness of dark current images depends on the total ionising dose that the camera is exposed to and the dose rate as well as on the applied exposure times.

  12. Measuring the speed of dark: Detecting dark energy perturbations

    International Nuclear Information System (INIS)

    Putter, Roland de; Huterer, Dragan; Linder, Eric V.

    2010-01-01

    The nature of dark energy can be probed not only through its equation of state but also through its microphysics, characterized by the sound speed of perturbations to the dark energy density and pressure. As the sound speed drops below the speed of light, dark energy inhomogeneities increase, affecting both cosmic microwave background and matter power spectra. We show that current data can put no significant constraints on the value of the sound speed when dark energy is purely a recent phenomenon, but can begin to show more interesting results for early dark energy models. For example, the best fit model for current data has a slight preference for dynamics [w(a)≠-1], degrees of freedom distinct from quintessence (c s ≠1), and early presence of dark energy [Ω de (a<<1)≠0]. Future data may open a new window on dark energy by measuring its spatial as well as time variation.

  13. Weak lensing: Dark Matter, Dark Energy and Dark Gravity

    International Nuclear Information System (INIS)

    Heavens, Alan

    2009-01-01

    In this non-specialist review I look at how weak lensing can provide information on the dark sector of the Universe. The review concentrates on what can be learned about Dark Matter, Dark Energy and Dark Gravity, and why. On Dark Matter, results on the confrontation of theoretical profiles with observation are reviewed, and measurements of neutrino masses discussed. On Dark Energy, the interest is whether this could be Einstein's cosmological constant, and prospects for high-precision studies of the equation of state are considered. On Dark Gravity, we consider the exciting prospects for future weak lensing surveys to distinguish General Relativity from extra-dimensional or other gravity theories.

  14. Dark properties and transient current response of Si0.95Ge0.05 n+p devices

    International Nuclear Information System (INIS)

    Ruzin, Arie; Marunko, S.; Abrosimov, N.V.; Riemann, H.

    2004-01-01

    In this study we present the dark properties of 'pin' devices fabricated with Czochralski grown Si 0.95 Ge 0.05 bulk single crystals. The growth of such material is most challenging because of the constitutional supercooling effect. The potential advantages of Si 1-x Ge x to be used for X- and gamma-ray detection applications are overviewed. At room temperature the generation current in the devices is too high for spectroscopy applications, but enables transient current technique (TCT) measurements. The current however drops significantly with moderate cooling. The effective majority carrier concentration is shown to be ∼2x10 14 cm -3 , and hole mobility ∼320 cm 2 /V s

  15. Dark influences: imprints of dark satellites on dwarf galaxies

    NARCIS (Netherlands)

    Starkenburg, T. K.; Helmi, A.

    Context. In the context of the current Λ cold dark matter cosmological model small dark matter halos are abundant and satellites of dwarf galaxies are expected to be predominantly dark. Since low mass galaxies have smaller baryon fractions, interactions with these satellites may leave particularly

  16. Dark clouds in particle physics and cosmology: the issues of dark matter and dark energy

    International Nuclear Information System (INIS)

    Zhang Xinmin

    2011-01-01

    Unveiling the nature of dark matter and dark energy is one of the main tasks of particle physics and cosmology in the 21st century. We first present an overview of the history and current status of research in cosmology, at the same time emphasizing the new challenges in particle physics. Then we focus on the scientific issues of dark energy, dark matter and anti-matter, and review the recent progress made in these fields. Finally, we discuss the prospects for future research on the experimental probing of dark matter and dark energy in China. (authors)

  17. The dark cube: dark and light character profiles

    Directory of Open Access Journals (Sweden)

    Danilo Garcia

    2016-02-01

    Full Text Available Background. Research addressing distinctions and similarities between people’s malevolent character traits (i.e., the Dark Triad: Machiavellianism, narcissism, and psychopathy has detected inconsistent linear associations to temperament traits. Additionally, these dark traits seem to have a common core expressed as uncooperativeness. Hence, some researchers suggest that the dark traits are best represented as one global construct (i.e., the unification argument rather than as ternary construct (i.e., the uniqueness argument. We put forward the dark cube (cf. Cloninger’s character cube comprising eight dark profiles that can be used to compare individuals who differ in one dark character trait while holding the other two constant. Our aim was to investigate in which circumstances individuals who are high in each one of the dark character traits differ in Cloninger’s “light” character traits: self-directedness, cooperativeness, and self-transcendence. We also investigated if people’s dark character profiles were associated to their light character profiles. Method. A total of 997 participants recruited from Amazon’s Mechanical Turk (MTurk responded to the Short Dark Triad and the Short Character Inventory. Participants were allocated to eight different dark profiles and eight light profiles based on their scores in each of the traits and any possible combination of high and low scores. We used three-way interaction regression analyses and t-tests to investigate differences in light character traits between individuals with different dark profiles. As a second step, we compared the individuals’ dark profile with her/his character profile using an exact cell-wise analysis conducted in the ROPstat software (http://www.ropstat.com. Results. Individuals who expressed high levels of Machiavellianism and those who expressed high levels of psychopathy also expressed low self-directedness and low cooperativeness. Individuals with high

  18. Biohydrogen production from combined dark-photo fermentation under a high ammonia content in the dark fermentation effluent

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chun-Yen [National Cheng Kung Univ., Tainan, Taiwan (China). Dept. of Chemical Engineering; National Cheng Kung Univ., Tainan, Taiwan (China). Sustainable Environment Research Center; Lo, Yung-Chung; Yeh, Kuei-Ling [National Cheng Kung Univ., Tainan, Taiwan (China). Dept. of Chemical Engineering; Chang, Jo-Shu [National Cheng Kung Univ., Tainan, Taiwan (China). Dept. of Chemical Engineering; National Cheng Kung Univ., Tainan, Taiwan (China). Sustainable Environment Research Center; National Cheng Kung Univ., Tainan, Taiwan (China). Microalgae Biotechnology and Bioengineering Lab.

    2010-07-01

    Integrated dark and photo (two-stage) fermentation was employed to enhance the performance of H{sub 2} production. First, the continuous dark fermentation using indigenous Clostridium butyricum CGS5 was carried out at 12 h HRT and fed with sucrose at a concentration of 18750 mg/l. The overall H{sub 2} production rate and H{sub 2} yield were fairly stable with a mean value of 87.5 ml/l/h and 1.015 mol H{sub 2}/mol sucrose, respectively. In addition, a relatively high ammonia nitrogen content (574 mg/l) in the dark fermentation effluent was observed. The soluble metabolites from dark fermentation, consisting mainly of butyric, lactic and acetic acids, were directly used as the influent of continuous photo-H{sub 2} production process inoculated with Rhodopseudomonas palutris WP 3-5 under the condition of 35oC, 10000 lux irradiation, pH 7.0 and 48 h HRT. The maximum overall hydrogen production rate from photo fermentation was 16.4 ml H{sub 2}/l/h, and the utilization of the soluble metabolites could reach 90%. The maximum H{sub 2} yield dramatically increased from 1.015 mol H{sub 2}/mol sucrose (in dark fermentation only) to 6.04 mol H{sub 2}/mol sucrose in the combined dark and photo fermentation. Surprisingly, the operation strategy applied in this work was able to attain an average NH{sub 3}-N removal efficiency of 92%, implying that our photo-H{sub 2} production system has a higher NH{sub 3}-N tolerance, demonstrating its high applicability in an integrated dark-photo fermentation system. (orig.)

  19. Illuminating dark photons with high-energy colliders

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, David [Maryland Center for Fundamental Physics, University of Maryland,College Park, MD 20742 (United States); Essig, Rouven [C.N. Yang Institute for Theoretical Physics, Stony Brook University,Stony Brook, NY 11794 (United States); Gori, Stefania [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario (Canada); Shelton, Jessie [Dept. of Physics, University of Illinois at Urbana-Champaign,1110 West Green Street, Urbana, IL 61801 (United States)

    2015-02-24

    High-energy colliders offer a unique sensitivity to dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model (SM) hypercharge. Dark photons can be detected in the exotic decay of the 125 GeV Higgs boson, h→ZZ{sub D}→4ℓ, and in Drell-Yan events, pp→Z{sub D}→ℓℓ. If the dark U(1) is broken by a hidden-sector Higgs mechanism, then mixing between the dark and SM Higgs bosons also allows the exotic decay h→Z{sub D}Z{sub D}→4ℓ. We show that the 14 TeV LHC and a 100 TeV proton-proton collider provide powerful probes of both exotic Higgs decay channels. In the case of kinetic mixing alone, direct Drell-Yan production offers the best sensitivity to Z{sub D}, and can probe ϵ≳9×10{sup −4} (4×10{sup −4}) at the HL-LHC (100 TeV pp collider). The exotic Higgs decay h→ZZ{sub D} offers slightly weaker sensitivity, but both measurements are necessary to distinguish the kinetically mixed dark photon from other scenarios. If Higgs mixing is also present, then the decay h→Z{sub D}Z{sub D} can allow sensitivity to the Z{sub D} for ϵ≳10{sup −9}−10{sup −6} (10{sup −10}−10{sup −7}) for the mass range 2m{sub μ}dark photon decays. We also compare the Z{sub D} sensitivity at pp colliders to the indirect, but model-independent, sensitivity of global fits to electroweak precision observables. We perform a global electroweak fit of the dark photon model, substantially updating previous work in the literature. Electroweak precision measurements at LEP, Tevatron, and the LHC exclude ϵ as low as 3×10{sup −2}. Sensitivity can be improved by up to a factor of ∼2 with HL-LHC data, and an additional factor of ∼4 with ILC/GigaZ data.

  20. High dynamic range low-noise focal plane readout for VLWIR applications implemented with current mode background subtraction

    Science.gov (United States)

    Yang, Guang; Sun, Chao; Shaw, Timothy; Wrigley, Chris; Peddada, Pavani; Blazejewski, Edward R.; Pain, Bedabrata

    1998-09-01

    Design and operation of a low noise CMOS focal pa;ne readout circuit with ultra-high charge handling capacity is presented. Designed for high-background, VLWIR detector readout, each readout unit cell use an accurate dynamic current memory for automatic subtraction of the dark pedestal in current domain enabling measurement of small signals 85 dB below the dark level. The redout circuit operates with low-power dissipation, high linearity, and is capable of handling pedestal currents up to 300 nA. Measurements indicate an effective charge handling capacity of over 5 X 10(superscript 9) charges/pixel with less than 10(superscript 5) electrons of input referred noise.

  1. Limits on dark radiation, early dark energy, and relativistic degrees of freedom

    International Nuclear Information System (INIS)

    Calabrese, Erminia; Melchiorri, Alessandro; Huterer, Dragan; Linder, Eric V.; Pagano, Luca

    2011-01-01

    Recent cosmological data analyses hint at the presence of an extra relativistic energy component in the early universe. This component is often parametrized as an excess of the effective neutrino number N eff over the standard value of 3.046. The excess relativistic energy could be an indication for an extra (sterile) neutrino, but early dark energy and barotropic dark energy also contribute to the relativistic degrees of freedom. We examine the capabilities of current and future data to constrain and discriminate between these explanations, and to detect the early dark energy density associated with them. We find that while early dark energy does not alter the current constraints on N eff , a dark radiation component, such as that provided by barotropic dark energy models, can substantially change current constraints on N eff , bringing its value back to agreement with the theoretical prediction. Both dark energy models also have implications for the primordial mass fraction of Helium Y p and the scalar perturbation index n s . The ongoing Planck satellite mission will be able to further discriminate between sterile neutrinos and early dark energy.

  2. Zero-Bias Offsets in the Low-Temperature Dark Current of Quantum-Well Infrared Photodetectors

    National Research Council Canada - National Science Library

    Singh, Anjali

    1999-01-01

    .... In this environment, the detector arrays may need to be operated at temperatures lower then 77 K. At these temperatures, tunneling mechanisms such as Fowler-Nordheim and trap-assisted tunneling could dominate the dark current...

  3. Negative Offset Operation of Four-Transistor CMOS Image Pixels for Increased Well Capacity and Suppressed Dark Current

    OpenAIRE

    Mheen, B.; Song, Y.J.; Theuwissen, J.P.

    2008-01-01

    This letter presents an electrical method to reduce dark current as well as increase well capacity of four-transistor pixels in a CMOS image sensor, utilizing a small negative offset voltage to the gate of the transfer (TX) transistor particularly only when the TX transistor is off. As a result, using a commercial pixel in a 0.18 ?m CMOS process, the voltage drop due to dark current of the pinned photodiode (PPD) is reduced by 6.1 dB and the well capacity is enhanced by 4.4 dB, which is attri...

  4. Dark matter and dark radiation

    International Nuclear Information System (INIS)

    Ackerman, Lotty; Buckley, Matthew R.; Carroll, Sean M.; Kamionkowski, Marc

    2009-01-01

    We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ('dark electromagnetism') that couples only to dark matter, not to the standard model. The dark matter consists of an equal number of positive and negative charges under the new force, but annihilations are suppressed if the dark-matter mass is sufficiently high and the dark fine-structure constant α-circumflex is sufficiently small. The correct relic abundance can be obtained if the dark matter also couples to the conventional weak interactions, and we verify that this is consistent with particle-physics constraints. The primary limit on α-circumflex comes from the demand that the dark matter be effectively collisionless in galactic dynamics, which implies α-circumflex -3 for TeV-scale dark matter. These values are easily compatible with constraints from structure formation and primordial nucleosynthesis. We raise the prospect of interesting new plasma effects in dark-matter dynamics, which remain to be explored.

  5. Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control.

    Science.gov (United States)

    Lee, Sang-Won; Cha, Seung-Hwan; Choi, Kyung-Jae; Kang, Byoung-Ho; Lee, Jae-Sung; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Gopalan, Sai-Anand; Kwon, Dae-Hyuk; Kang, Shin-Won

    2016-01-07

    We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL) spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 10³ higher than that of the dark current.

  6. Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control

    Directory of Open Access Journals (Sweden)

    Sang-Won Lee

    2016-01-01

    Full Text Available We propose a solution-processable ultraviolet (UV photodetector with a pn-heterojunction hybrid photoactive layer (HPL that is composed of poly-n-vinylcarbazole (PVK as a p-type polymer and ZnO nanoparticles (NPs as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 103 higher than that of the dark current.

  7. Neutrino physics with dark matter experiments and the signature of new baryonic neutral currents

    International Nuclear Information System (INIS)

    Pospelov, Maxim

    2011-01-01

    New neutrino states ν b , sterile under the standard model interactions, can be coupled to baryons via the isoscalar vector currents that are much stronger than the standard model weak interactions. If some fraction of solar neutrinos oscillate into ν b on their way to Earth, the coherently enhanced elastic ν b -nucleus scattering can generate a strong signal in the dark matter detectors. For the interaction strength a few hundred times stronger than the weak force, the elastic ν b -nucleus scattering via new baryonic currents may account for the existing anomalies in the direct detection dark matter experiments at low recoil. We point out that for solar-neutrino energies, the baryon-current-induced inelastic scattering is suppressed, so that the possible enhancement of a new force is not in conflict with signals at dedicated neutrino detectors. We check this explicitly by calculating the ν b -induced deuteron breakup, and the excitation of a 4.4 MeV γ line in 12 C. A stronger-than-weak force coupled to the baryonic current implies the existence of a new Abelian gauge group U(1) B with a relatively light gauge boson.

  8. Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector

    Science.gov (United States)

    Berryman, Jeffrey M.; de Gouvêa, André; Kelly, Kevin J.; Zhang, Yue

    2017-10-01

    All pieces of concrete evidence for phenomena outside the standard model (SM)—neutrino masses and dark matter—are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral S U (3 )×S U (2 ) gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark S U (2 ) is spontaneously broken while the dark S U (3 ) confines at low energies. At the renormalizable level, the dark sector contains massless fermions—dark leptons—and stable massive particles—dark protons. We find that dark protons with masses between 10 and 100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new "neutrino" and "dark-matter" degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early Universe cosmology while indirect searches for dark matter involve, decisively, dark-matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.

  9. Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

    Science.gov (United States)

    Drlica-Wagner, Alex; Gomez-Vargas, German A.; Hewitt, John W.; Linden, Tim; Tibaldo, Luigi

    2014-01-01

    Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (approximately 3 x 10 (sup -26) cubic centimeters per second) for dark matter masses less than or approximately 30 gigaelectronvolts annihilating via the B/B- bar oscillation or tau/antitau channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

  10. Searching for dark matter annihilation in the Smith high-velocity cloud

    International Nuclear Information System (INIS)

    Drlica-Wagner, Alex; Gómez-Vargas, Germán A.; Hewitt, John W.; Linden, Tim; Tibaldo, Luigi

    2014-01-01

    Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (∼ 3 × 10 –26 cm 3 s –1 ) for dark matter masses ≲ 30 GeV annihilating via the b b-bar or τ + τ – channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

  11. Searching for dark matter annihilation in the Smith high-velocity cloud

    Energy Technology Data Exchange (ETDEWEB)

    Drlica-Wagner, Alex [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Gómez-Vargas, Germán A. [Departamento de Fisíca, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Santiago (Chile); Hewitt, John W. [CRESST, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States); Linden, Tim [The Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Tibaldo, Luigi [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2014-07-20

    Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (∼ 3 × 10{sup –26} cm{sup 3} s{sup –1}) for dark matter masses ≲ 30 GeV annihilating via the b b-bar or τ{sup +}τ{sup –} channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

  12. The dark side of cosmology: dark matter and dark energy.

    Science.gov (United States)

    Spergel, David N

    2015-03-06

    A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of "dark matter," a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of "dark energy," energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales. Copyright © 2015, American Association for the Advancement of Science.

  13. Current status of direct dark matter detection experiments

    Science.gov (United States)

    Liu, Jianglai; Chen, Xun; Ji, Xiangdong

    2017-03-01

    Much like ordinary matter, dark matter might consist of elementary particles, and weakly interacting massive particles are one of the prime suspects. During the past decade, the sensitivity of experiments trying to directly detect them has improved by three to four orders of magnitude, but solid evidence for their existence is yet to come. We overview the recent progress in direct dark matter detection experiments and discuss future directions.

  14. Minority carrier lifetime and dark current measurements in mid-wavelength infrared InAs0.91Sb0.09 alloy nBn photodetectors

    Science.gov (United States)

    Olson, B. V.; Kim, J. K.; Kadlec, E. A.; Klem, J. F.; Hawkins, S. D.; Leonhardt, D.; Coon, W. T.; Fortune, T. R.; Cavaliere, M. A.; Tauke-Pedretti, A.; Shaner, E. A.

    2015-11-01

    Carrier lifetime and dark current measurements are reported for a mid-wavelength infrared InAs0.91Sb0.09 alloy nBn photodetector. Minority carrier lifetimes are measured using a non-contact time-resolved microwave technique on unprocessed portions of the nBn wafer and the Auger recombination Bloch function parameter is determined to be |F1F2|=0.292 . The measured lifetimes are also used to calculate the expected diffusion dark current of the nBn devices and are compared with the experimental dark current measured in processed photodetector pixels from the same wafer. Excellent agreement is found between the two, highlighting the important relationship between lifetimes and diffusion currents in nBn photodetectors.

  15. Dark Side of the Universe

    CERN Document Server

    2016-01-01

    The Dark Side of the Universe (DSU) workshops bring together a wide range of theorists and experimentalists to discuss current ideas on models of the dark side, and relate them to current and future experiments. This year's DSU will take place in the colorful Norwegian city of Bergen. Topics include dark matter, dark energy, cosmology, and physics beyond the standard model. One of the goals of the workshop is to expose in particular students and young researchers to the fascinating topics of dark matter and dark energy, and to provide them with the opportunity to meet some of the best researchers in these areas .

  16. Dark energy

    International Nuclear Information System (INIS)

    Wang, Yun

    2010-01-01

    Dark energy research aims to illuminate the mystery of the observed cosmic acceleration, one of the fundamental problems in physics and astronomy today. This book presents a systematic and detailed review of the current state of dark energy research, with the focus on the examination of the major observational techniques for probing dark energy. It can be used as a textbook to train students and others who wish to enter this extremely active field in cosmology.

  17. Cosmic Visions Dark Energy. Science

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Heitmann, Katrin [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Hirata, Chris [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Honscheid, Klaus [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Roodman, Aaron [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Seljak, Uroš [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Slosar, Anže [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Trodden, Mark [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-04-26

    Cosmic surveys provide crucial information about high energy physics including strong evidence for dark energy, dark matter, and inflation. Ongoing and upcoming surveys will start to identify the underlying physics of these new phenomena, including tight constraints on the equation of state of dark energy, the viability of modified gravity, the existence of extra light species, the masses of the neutrinos, and the potential of the field that drove inflation. Even after the Stage IV experiments, DESI and LSST, complete their surveys, there will still be much information left in the sky. This additional information will enable us to understand the physics underlying the dark universe at an even deeper level and, in case Stage IV surveys find hints for physics beyond the current Standard Model of Cosmology, to revolutionize our current view of the universe. There are many ideas for how best to supplement and aid DESI and LSST in order to access some of this remaining information and how surveys beyond Stage IV can fully exploit this regime. These ideas flow to potential projects that could start construction in the 2020's.

  18. Cosmic Visions Dark Energy: Science

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Slosar, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Heitmann, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hirata, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Honscheid, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roodman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Seljak, U. [Brookhaven National Lab. (BNL), Upton, NY (United States); Trodden, M. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-04-26

    Cosmic surveys provide crucial information about high energy physics including strong evidence for dark energy, dark matter, and inflation. Ongoing and upcoming surveys will start to identify the underlying physics of these new phenomena, including tight constraints on the equation of state of dark energy, the viability of modified gravity, the existence of extra light species, the masses of the neutrinos, and the potential of the field that drove inflation. Even after the Stage IV experiments, DESI and LSST, complete their surveys, there will still be much information left in the sky. This additional information will enable us to understand the physics underlying the dark universe at an even deeper level and, in case Stage IV surveys find hints for physics beyond the current Standard Model of Cosmology, to revolutionize our current view of the universe. There are many ideas for how best to supplement and aid DESI and LSST in order to access some of this remaining information and how surveys beyond Stage IV can fully exploit this regime. These ideas flow to potential projects that could start construction in the 2020's.

  19. Dark matter haloes: a multistream view

    Science.gov (United States)

    Ramachandra, Nesar S.; Shandarin, Sergei F.

    2017-09-01

    Mysterious dark matter constitutes about 85 per cent of all masses in the Universe. Clustering of dark matter plays a dominant role in the formation of all observed structures on scales from a fraction to a few hundreds of Mega-parsecs. Galaxies play a role of lights illuminating these structures so they can be observed. The observations in the last several decades have unveiled opulent geometry of these structures currently known as the cosmic web. Haloes are the highest concentrations of dark matter and host luminous galaxies. Currently the most accurate modelling of dark matter haloes is achieved in cosmological N-body simulations. Identifying the haloes from the distribution of particles in N-body simulations is one of the problems attracting both considerable interest and efforts. We propose a novel framework for detecting potential dark matter haloes using the field unique for dark matter-multistream field. The multistream field emerges at the non-linear stage of the growth of perturbations because the dark matter is collisionless. Counting the number of velocity streams in gravitational collapses supplements our knowledge of spatial clustering. We assume that the virialized haloes have convex boundaries. Closed and convex regions of the multistream field are hence isolated by imposing a positivity condition on all three eigenvalues of the Hessian estimated on the smoothed multistream field. In a single-scale analysis of high multistream field resolution and low softening length, the halo substructures with local multistream maxima are isolated as individual halo sites.

  20. New interactions in the dark sector mediated by dark energy

    International Nuclear Information System (INIS)

    Brookfield, Anthony W.; Bruck, Carsten van de; Hall, Lisa M. H.

    2008-01-01

    Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example, two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles

  1. RTS noise and dark current white defects reduction using selective averaging based on a multi-aperture system.

    Science.gov (United States)

    Zhang, Bo; Kagawa, Keiichiro; Takasawa, Taishi; Seo, Min Woong; Yasutomi, Keita; Kawahito, Shoji

    2014-01-16

    In extremely low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible. In this paper, a multi-aperture imaging system and selective averaging method which removes the RTS noise and the dark current white defects by minimizing the synthetic sensor noise at every pixel is proposed. In the multi-aperture imaging system, a very small synthetic F-number which is much smaller than 1.0 is achieved by increasing optical gain with multiple lenses. It is verified by simulation that the effective noise normalized by optical gain in the peak of noise histogram is reduced from 1.38e⁻ to 0.48 e⁻ in a 3 × 3-aperture system using low-noise CMOS image sensors based on folding-integration and cyclic column ADCs. In the experiment, a prototype 3 × 3-aperture camera, where each aperture has 200 × 200 pixels and an imaging lens with a focal length of 3.0 mm and F-number of 3.0, is developed. Under a low-light condition, in which the maximum average signal is 11e⁻ per aperture, the RTS and dark current white defects are removed and the peak signal-to-noise ratio (PSNR) of the image is increased by 6.3 dB.

  2. Direct search for dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jonghee; /Fermilab

    2009-12-01

    Dark matter is hypothetical matter which does not interact with electromagnetic radiation. The existence of dark matter is only inferred from gravitational effects of astrophysical observations to explain the missing mass component of the Universe. Weakly Interacting Massive Particles are currently the most popular candidate to explain the missing mass component. I review the current status of experimental searches of dark matter through direct detection using terrestrial detectors.

  3. High Energy Electron Signals from Dark Matter Annihilation in the Sun

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Philip; /SLAC; Toro, Natalia; /Stanford U., ITP; Weiner, Neal; Yavin, Itay; /New York U., CCPP

    2012-04-09

    In this paper we discuss two mechanisms by which high energy electrons resulting from dark matter annihilations in or near the Sun can arrive at the Earth. Specifically, electrons can escape the sun if DM annihilates into long-lived states, or if dark matter scatters inelastically, which would leave a halo of dark matter outside of the sun. Such a localized source of electrons may affect the spectra observed by experiments with narrower fields of view oriented towards the sun, such as ATIC, differently from those with larger fields of view such as Fermi. We suggest a simple test of these possibilities with existing Fermi data that is more sensitive than limits from final state radiation. If observed, such a signal will constitute an unequivocal signature of dark matter.

  4. Cold dark matter plus not-so-clumpy dark relics

    International Nuclear Information System (INIS)

    Diamanti, Roberta; Ando, Shin'ichiro; Weniger, Christoph; Gariazzo, Stefano; Mena, Olga

    2017-01-01

    Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction f ncdm of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are f ncdm ≤0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are f ncdm ≤0.43 (0.45), respectively.

  5. Cold dark matter plus not-so-clumpy dark relics

    Energy Technology Data Exchange (ETDEWEB)

    Diamanti, Roberta; Ando, Shin' ichiro; Weniger, Christoph [GRAPPA, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Gariazzo, Stefano; Mena, Olga, E-mail: r.diamanti@uva.nl, E-mail: s.ando@uva.nl, E-mail: gariazzo@to.infn.it, E-mail: omena@ific.uv.es, E-mail: c.weniger@uva.nl [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de Valencia, Apartado de Correos 22085, E-46071, Valencia (Spain)

    2017-06-01

    Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction f {sub ncdm} of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are f {sub ncdm}≤0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are f {sub ncdm}≤0.43 (0.45), respectively.

  6. Searching for dark matter-dark energy interactions: Going beyond the conformal case

    Science.gov (United States)

    van de Bruck, Carsten; Mifsud, Jurgen

    2018-01-01

    We consider several cosmological models which allow for nongravitational direct couplings between dark matter and dark energy. The distinguishing cosmological features of these couplings can be probed by current cosmological observations, thus enabling us to place constraints on these specific interactions which are composed of the conformal and disformal coupling functions. We perform a global analysis in order to independently constrain the conformal, disformal, and mixed interactions between dark matter and dark energy by combining current data from: Planck observations of the cosmic microwave background radiation anisotropies, a combination of measurements of baryon acoustic oscillations, a supernova type Ia sample, a compilation of Hubble parameter measurements estimated from the cosmic chronometers approach, direct measurements of the expansion rate of the Universe today, and a compilation of growth of structure measurements. We find that in these coupled dark-energy models, the influence of the local value of the Hubble constant does not significantly alter the inferred constraints when we consider joint analyses that include all cosmological probes. Moreover, the parameter constraints are remarkably improved with the inclusion of the growth of structure data set measurements. We find no compelling evidence for an interaction within the dark sector of the Universe.

  7. DarkBit. A GAMBIT module for computing dark matter observables and likelihoods

    Energy Technology Data Exchange (ETDEWEB)

    Bringmann, Torsten; Dal, Lars A. [University of Oslo, Department of Physics, Oslo (Norway); Conrad, Jan; Edsjoe, Joakim; Farmer, Ben [AlbaNova University Centre, Oskar Klein Centre for Cosmoparticle Physics, Stockholm (Sweden); Stockholm University, Department of Physics, Stockholm (Sweden); Cornell, Jonathan M. [McGill University, Department of Physics, Montreal, QC (Canada); Kahlhoefer, Felix; Wild, Sebastian [DESY, Hamburg (Germany); Kvellestad, Anders; Savage, Christopher [NORDITA, Stockholm (Sweden); Putze, Antje [LAPTh, Universite de Savoie, CNRS, Annecy-le-Vieux (France); Scott, Pat [Blackett Laboratory, Imperial College London, Department of Physics, London (United Kingdom); Weniger, Christoph [University of Amsterdam, GRAPPA, Institute of Physics, Amsterdam (Netherlands); White, Martin [University of Adelaide, Department of Physics, Adelaide, SA (Australia); Australian Research Council Centre of Excellence for Particle Physics at the Tera-scale, Parkville (Australia); Collaboration: The GAMBIT Dark Matter Workgroup

    2017-12-15

    We introduce DarkBit, an advanced software code for computing dark matter constraints on various extensions to the Standard Model of particle physics, comprising both new native code and interfaces to external packages. This release includes a dedicated signal yield calculator for gamma-ray observations, which significantly extends current tools by implementing a cascade-decay Monte Carlo, as well as a dedicated likelihood calculator for current and future experiments (gamLike). This provides a general solution for studying complex particle physics models that predict dark matter annihilation to a multitude of final states. We also supply a direct detection package that models a large range of direct detection experiments (DDCalc), and that provides the corresponding likelihoods for arbitrary combinations of spin-independent and spin-dependent scattering processes. Finally, we provide custom relic density routines along with interfaces to DarkSUSY, micrOMEGAs, and the neutrino telescope likelihood package nulike. DarkBit is written in the framework of the Global And Modular Beyond the Standard Model Inference Tool (GAMBIT), providing seamless integration into a comprehensive statistical fitting framework that allows users to explore new models with both particle and astrophysics constraints, and a consistent treatment of systematic uncertainties. In this paper we describe its main functionality, provide a guide to getting started quickly, and show illustrative examples for results obtained with DarkBit (both as a stand-alone tool and as a GAMBIT module). This includes a quantitative comparison between two of the main dark matter codes (DarkSUSY and micrOMEGAs), and application of DarkBit's advanced direct and indirect detection routines to a simple effective dark matter model. (orig.)

  8. Effects of adsorbed pyridine derivatives and ultrathin atomic-layer-deposited alumina coatings on the conduction band-edge energy of TiO2 and on redox-shuttle-derived dark currents.

    Science.gov (United States)

    Katz, Michael J; Vermeer, Michael J D; Farha, Omar K; Pellin, Michael J; Hupp, Joseph T

    2013-01-15

    Both the adsorption of t-butylpyridine and the atomic-layer deposition of ultrathin conformal coatings of insulators (such as alumina) are known to boost open-circuit photovoltages substantially for dye-sensitized solar cells. One attractive interpretation is that these modifiers significantly shift the conduction-edge energy of the electrode, thereby shifting the onset potential for dark current arising from the interception of injected electrons by solution-phase redox shuttle components such as Co(phenanthroline)(3)(3+) and triiodide. For standard, high-area, nanoporous photoelectrodes, band-edge energies are difficult to measure directly. In contrast, for flat electrodes they are readily accessible from Mott-Schottky analyses of impedance data. Using such electrodes (specifically TiO(2)), we find that neither organic nor inorganic electrode-surface modifiers shift the conduction-band-edge energy sufficiently to account fully for the beneficial effects on electrode behavior (i.e., the suppression of dark current). Additional experiments reveal that the efficacy of ultrathin coatings of Al(2)O(3) arises chiefly from the passivation of redox-catalytic surface states. In contrast, adsorbed t-butylpyridine appears to suppress dark currents mainly by physically blocking access of shuttle molecules to the electrode surface. Studies with other derivatives of pyridine, including sterically and/or electronically diverse derivatives, show that heterocycle adsorption and the concomitant suppression of dark current does not require the coordination of surface Ti(IV) or Al(III) atoms. Notably, the favorable (i.e., negative) shifts in onset potential for the flow of dark current engendered by organic and inorganic surface modifiers are additive. Furthermore, they appear to be largely insensitive to the identity of shuttle molecules.

  9. Dark matter and dark energy interactions: theoretical challenges, cosmological implications and observational signatures.

    Science.gov (United States)

    Wang, B; Abdalla, E; Atrio-Barandela, F; Pavón, D

    2016-09-01

    Models where dark matter and dark energy interact with each other have been proposed to solve the coincidence problem. We review the motivations underlying the need to introduce such interaction, its influence on the background dynamics and how it modifies the evolution of linear perturbations. We test models using the most recent observational data and we find that the interaction is compatible with the current astronomical and cosmological data. Finally, we describe the forthcoming data sets from current and future facilities that are being constructed or designed that will allow a clearer understanding of the physics of the dark sector.

  10. Coupled dark matter-dark energy in light of near Universe observations

    CERN Document Server

    Honorez, Laura Lopez; Mena, Olga; Verde, Licia; Jimenez, Raul

    2010-01-01

    Cosmological analysis based on currently available observations are unable to rule out a sizeable coupling among the dark energy and dark matter fluids. We explore a variety of coupled dark matter-dark energy models, which satisfy cosmic microwave background constraints, in light of low redshift and near universe observations. We illustrate the phenomenology of different classes of dark coupling models, paying particular attention in distinguishing between effects that appear only on the expansion history and those that appear in the growth of structure. We find that while a broad class of dark coupling models are effectively models where general relativity (GR) is modified --and thus can be probed by a combination of tests for the expansion history and the growth of structure--, there is a class of dark coupling models where gravity is still GR, but the growth of perturbations is, in principle modified. While this effect is small in the specific models we have considered, one should bear in mind that an inco...

  11. Dark matter universe

    Science.gov (United States)

    Bahcall, Neta A.

    2015-01-01

    Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle. PMID:26417091

  12. Dark matter universe.

    Science.gov (United States)

    Bahcall, Neta A

    2015-10-06

    Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

  13. Signatures of dark radiation in neutrino and dark matter detectors

    Science.gov (United States)

    Cui, Yanou; Pospelov, Maxim; Pradler, Josef

    2018-05-01

    We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In particular, for interacting dark radiation carrying a typical momentum of ˜30 MeV /c , both types of experiments provide competitive constraints. This study also demonstrates that non-standard sources of neutrino emission (e.g., via dark matter decay) are capable of creating a "neutrino floor" for dark matter direct detection that is closer to current bounds than is expected from standard neutrino sources.

  14. Observational constraints on variable equation of state parameters of dark matter and dark energy after Planck

    Directory of Open Access Journals (Sweden)

    Suresh Kumar

    2014-10-01

    Full Text Available In this paper, we study a cosmological model in general relativity within the framework of spatially flat Friedmann–Robertson–Walker space–time filled with ordinary matter (baryonic, radiation, dark matter and dark energy, where the latter two components are described by Chevallier–Polarski–Linder equation of state parameters. We utilize the observational data sets from SNLS3, BAO and Planck + WMAP9 + WiggleZ measurements of matter power spectrum to constrain the model parameters. We find that the current observational data offer tight constraints on the equation of state parameter of dark matter. We consider the perturbations and study the behavior of dark matter by observing its effects on CMB and matter power spectra. We find that the current observational data favor the cold dark matter scenario with the cosmological constant type dark energy at the present epoch.

  15. Observational constraints on variable equation of state parameters of dark matter and dark energy after Planck

    International Nuclear Information System (INIS)

    Kumar, Suresh; Xu, Lixin

    2014-01-01

    In this paper, we study a cosmological model in general relativity within the framework of spatially flat Friedmann–Robertson–Walker space–time filled with ordinary matter (baryonic), radiation, dark matter and dark energy, where the latter two components are described by Chevallier–Polarski–Linder equation of state parameters. We utilize the observational data sets from SNLS3, BAO and Planck + WMAP9 + WiggleZ measurements of matter power spectrum to constrain the model parameters. We find that the current observational data offer tight constraints on the equation of state parameter of dark matter. We consider the perturbations and study the behavior of dark matter by observing its effects on CMB and matter power spectra. We find that the current observational data favor the cold dark matter scenario with the cosmological constant type dark energy at the present epoch

  16. Dark matter: Theoretical perspectives

    International Nuclear Information System (INIS)

    Turner, M.S.

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ''new physics.'' The compelling candidates are: a very light axion ( 10 -6 eV--10 -4 eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos

  17. Ultra compact 45 GHz CMOS compatible Germanium waveguide photodiode with low dark current.

    Science.gov (United States)

    DeRose, Christopher T; Trotter, Douglas C; Zortman, William A; Starbuck, Andrew L; Fisher, Moz; Watts, Michael R; Davids, Paul S

    2011-12-05

    We present a compact 1.3 × 4 μm2 Germanium waveguide photodiode, integrated in a CMOS compatible silicon photonics process flow. This photodiode has a best-in-class 3 dB cutoff frequency of 45 GHz, responsivity of 0.8 A/W and dark current of 3 nA. The low intrinsic capacitance of this device may enable the elimination of transimpedance amplifiers in future optical data communication receivers, creating ultra low power consumption optical communications.

  18. Dark Tourism and Destination Marketing

    OpenAIRE

    Jahnke, Daniela

    2013-01-01

    This thesis is about the dark tourism and destination marketing. The aim of the thesis is to display how these two terms can be combined. The term dark tourism is a relatively new research area; therefore the thesis will provide an outlook of the current situation of dark tourism. It starts with the beginning of dark tourism and continuous to the managerial aspects of dark tourism sites. The second part of the theoretical background is about destination marketing. It provides an overvie...

  19. Dark group: dark energy and dark matter

    International Nuclear Information System (INIS)

    Macorra, A. de la

    2004-01-01

    We study the possibility that a dark group, a gauge group with particles interacting with the standard model particles only via gravity, is responsible for containing the dark energy and dark matter required by present day observations. We show that it is indeed possible and we determine the constrains for the dark group. The non-perturbative effects generated by a strong gauge coupling constant can de determined and a inverse power law scalar potential IPL for the dark meson fields is generated parameterizing the dark energy. On the other hand it is the massive particles, e.g., dark baryons, of the dark gauge group that give the corresponding dark matter. The mass of the dark particles is of the order of the condensation scale Λ c and the temperature is smaller then the photon's temperature. The dark matter is of the warm matter type. The only parameters of the model are the number of particles of the dark group. The allowed values of the different parameters are severely restricted. The dark group energy density at Λ c must be Ω DGc ≤0.17 and the evolution and acceptable values of dark matter and dark energy leads to a constrain of Λ c and the IPL parameter n giving Λ c =O(1-10 3 ) eV and 0.28≤n≤1.04

  20. Dark matter from decaying topological defects

    International Nuclear Information System (INIS)

    Hindmarsh, Mark; Kirk, Russell; West, Stephen M.

    2014-01-01

    We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or ''top-down'' (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p−4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large ''boost factor'' enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on Gμ for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits

  1. BUV/Nimbus-4 Dark Current Study Working Data V001 (BUVN4L1DCW) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-4 BUV Level-1 Dark Current Study Working Data is derived from the BUV Level 1 Radiance (RUT) product and contains the geophysical indices and...

  2. Particle Dark Matter (1/4)

    CERN Multimedia

    CERN. Geneva

    2011-01-01

    I review the phenomenology of particle dark matter, including the process of thermal freeze-out in the early universe, and the direct and indirect detection of WIMPs. I also describe some of the most popular particle candidates for dark matter and summarize the current status of the quest to discover dark matter's particle identity.

  3. Dark matter: Theoretical perspectives

    International Nuclear Information System (INIS)

    Turner, M.S.

    1993-01-01

    The author both reviews and makes the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the open-quotes standard modelclose quotes of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for open-quotes new physics.close quotes The compelling candidates are a very light axion (10 -6 --10 -4 eV), a light neutrino (20--90 eV), and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. The author briefly mentions more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. 119 refs

  4. Dark matter: Theoretical perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Turner, M.S. (Chicago Univ., IL (United States). Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL (United States))

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for new physics.'' The compelling candidates are: a very light axion ( 10[sup [minus]6] eV--10[sup [minus]4] eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  5. Dark matter: Theoretical perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ``new physics.`` The compelling candidates are: a very light axion ( 10{sup {minus}6} eV--10{sup {minus}4} eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  6. Short-wavelength infrared imaging using low dark current InGaAs detector arrays and vertical-cavity surface-emitting laser illuminators

    Science.gov (United States)

    Macdougal, Michael; Geske, Jon; Wang, Chad; Follman, David

    2011-06-01

    We describe the factors that go into the component choices for a short wavelength IR (SWIR) imager, which include the SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can achieve well below 1.5 nA/cm2 for 15 μm devices at 7 °C. In addition, we have mated our InGaAs detector arrays to 640×512 readout integrated integrated circuits to make focal plane arrays (FPAs). The resulting FPAs are capable of imaging photon fluxes with wavelengths between 1 and 1.6 μm at low light levels. The dark current associated with these FPAs is extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0 °C. Noise due to the readout can be reduced from 95 to 57 electrons by using off-chip correlated double sampling. In addition, Aerius has developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle illumination, and provide artifact-free imagery versus conventional laser illuminators.

  7. GUT models at current and future hadron colliders and implications to dark matter searches

    Science.gov (United States)

    Arcadi, Giorgio; Lindner, Manfred; Mambrini, Yann; Pierre, Mathias; Queiroz, Farinaldo S.

    2017-08-01

    Grand Unified Theories (GUT) offer an elegant and unified description of electromagnetic, weak and strong interactions at high energy scales. A phenomenological and exciting possibility to grasp GUT is to search for TeV scale observables arising from Abelian groups embedded in GUT constructions. That said, we use dilepton data (ee and μμ) that has been proven to be a golden channel for a wide variety of new phenomena expected in theories beyond the Standard Model to probe GUT-inspired models. Since heavy dilepton resonances feature high signal selection efficiencies and relatively well-understood backgrounds, stringent and reliable bounds can be placed on the mass of the Z‧ gauge boson arising in such theories. In this work, we obtain 95% C.L. limits on the Z‧ mass for several GUT-models using current and future proton-proton colliders with √{ s} = 13 TeV , 33 TeV ,and 100 TeV, and put them into perspective with dark matter searches in light of the next generation of direct detection experiments.

  8. GUT models at current and future hadron colliders and implications to dark matter searches

    Directory of Open Access Journals (Sweden)

    Giorgio Arcadi

    2017-08-01

    Full Text Available Grand Unified Theories (GUT offer an elegant and unified description of electromagnetic, weak and strong interactions at high energy scales. A phenomenological and exciting possibility to grasp GUT is to search for TeV scale observables arising from Abelian groups embedded in GUT constructions. That said, we use dilepton data (ee and μμ that has been proven to be a golden channel for a wide variety of new phenomena expected in theories beyond the Standard Model to probe GUT-inspired models. Since heavy dilepton resonances feature high signal selection efficiencies and relatively well-understood backgrounds, stringent and reliable bounds can be placed on the mass of the Z′ gauge boson arising in such theories. In this work, we obtain 95% C.L. limits on the Z′ mass for several GUT-models using current and future proton–proton colliders with s=13 TeV,33 TeV,and100 TeV, and put them into perspective with dark matter searches in light of the next generation of direct detection experiments.

  9. Current trends in non-accelerator particle physics: 1, Neutrino mass and oscillation. 2, High energy neutrino astrophysics. 3, Detection of dark matter. 4, Search for strange quark matter. 5, Magnetic monopole searches

    International Nuclear Information System (INIS)

    He, Yudong

    1995-07-01

    This report is a compilation of papers reflecting current trends in non-accelerator particle physics, corresponding to talks that its author was invited to present at the Workshop on Tibet Cosmic Ray Experiment and Related Physics Topics held in Beijing, China, April 4--13, 1995. The papers are entitled 'Neutrino Mass and Oscillation', 'High Energy Neutrino Astrophysics', 'Detection of Dark Matter', 'Search for Strange Quark Matter', and 'Magnetic Monopole Searches'. The report is introduced by a survey of the field and a brief description of each of the author's papers

  10. Nonlocal astrophysics dark matter, dark energy and physical vacuum

    CERN Document Server

    Alexeev, Boris V

    2017-01-01

    Non-Local Astrophysics: Dark Matter, Dark Energy and Physical Vacuum highlights the most significant features of non-local theory, a highly effective tool for solving many physical problems in areas where classical local theory runs into difficulties. The book provides the fundamental science behind new non-local astrophysics, discussing non-local kinetic and generalized hydrodynamic equations, non-local parameters in several physical systems, dark matter, dark energy, black holes and gravitational waves. Devoted to the solution of astrophysical problems from the position of non-local physics Provides a solution for dark matter and dark energy Discusses cosmological aspects of the theory of non-local physics Includes a solution for the problem of the Hubble Universe expansion, and of the dependence of the orbital velocity from the center of gravity

  11. Dark matter maps reveal cosmic scaffolding.

    Science.gov (United States)

    Massey, Richard; Rhodes, Jason; Ellis, Richard; Scoville, Nick; Leauthaud, Alexie; Finoguenov, Alexis; Capak, Peter; Bacon, David; Aussel, Hervé; Kneib, Jean-Paul; Koekemoer, Anton; McCracken, Henry; Mobasher, Bahram; Pires, Sandrine; Refregier, Alexandre; Sasaki, Shunji; Starck, Jean-Luc; Taniguchi, Yoshi; Taylor, Andy; Taylor, James

    2007-01-18

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter--whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built.

  12. Dark matter maps reveal cosmic scaffolding

    Energy Technology Data Exchange (ETDEWEB)

    Massey, R; Rhodes, J; Ellis, R; Scoville, N; Capak, P [CALTECH, Pasadena, CA 91125 (United States); Rhodes, J [CALTECH, Jet Prop Lab, Pasadena, CA 91109 (United States); Leauthaud, A; Kneib, J P [Lab Astrophys Marseille, F-13376 Marseille, (France); Finoguenov, A [Max Planck Inst Extraterr Phys, D-85748 Garching, (Germany); Bacon, D; Taylor, A [Inst Astron, Edinburgh EH9 3HJ, Midlothian, (United Kingdom); Aussel, H; Refregier, A [CNRS, CEA, Unite Mixte Rech, AIM, F-91191 Gif Sur Yvette, (France); Koekemoer, A; Mobasher, B [Univ Paris 07, CE Saclay, UMR 7158, F-91191 Gif Sur Yvette, (France); McCracken, H [Space Telescope Sci Inst, Baltimore, MD 21218 (United States); Pires, S; Starck, J L [Univ Paris 06, Inst Astrophys Paris, F-75014 Paris, (France); Pires, S [Ctr Etud Saclay, CEA, DSM, DAPNIA, SEDI, F-91191 Gif Sur Yvette, (France); Sasaki, S; Taniguchi, Y [Ehime Univ, Dept Phys, Matsuyama, Ehime 7908577, (Japan); Taylor, J [Univ Waterloo, Dept Phys and Astron, Waterloo, ON N2L 3G1, (Canada)

    2007-07-01

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter - whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built. (authors)

  13. Dark matter maps reveal cosmic scaffolding

    International Nuclear Information System (INIS)

    Massey, R.; Rhodes, J.; Ellis, R.; Scoville, N.; Capak, P.; Rhodes, J.; Leauthaud, A.; Kneib, J.P.; Finoguenov, A.; Bacon, D.; Taylor, A.; Aussel, H.; Refregier, A.; Koekemoer, A.; Mobasher, B.; McCracken, H.; Pires, S.; Starck, J.L.; Pires, S.; Sasaki, S.; Taniguchi, Y.; Taylor, J.

    2007-01-01

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter - whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built. (authors)

  14. Indirect searches of dark matter, and the galactic center at very high energy with H.E.S.S

    International Nuclear Information System (INIS)

    Viana, Aion

    2012-01-01

    H.E.S.S. (High Energy Stereoscopic System) is an array of four identical imaging atmospheric Cherenkov telescopes, designed to observe very high energy γ-rays (E > 100 GeV). The observation of such γ-rays plays a crucial role in the understanding of extreme non-thermal phenomena in the Universe. These γ-rays can be used for instance to search for annihilations of dark matter particles in dense environments of the Universe. This thesis presents a series of data analysis and phenomenological studies on two main subject of the γ-ray astronomy: the indirect searches of dark matter, and the study of the Galactic Center region. The indirect dark matter searches focus on the study of two classes of targets: dwarf galaxies and galaxy clusters. A detailed study of the H.E.S.S. observations towards the Sculptor and Carina dwarf galaxies, and towards the Fornax galaxy cluster are presented. In the absence, of a significant signal coming from these object, constraints on the annihilation cross section of dark matter particle candidates are derived. Particular consideration is given to different processes from particle physics and astrophysics which might give rise to additional contributions to the signal expected from a dark matter particle annihilation, such as the Sommerfeld effect and dark matter halo substructures. The current H.E.S.S. dark matter constraints towards the Sagittarius are updated in light of recent realistic dark matter halo models. A prospect on the sensitivity of the future generation of Cherenkov telescopes, i.e. CTA (Cherenkov Telescope Array), for the detection of a dark matter annihilation signal and conventional γ-ray emissions are also given. The second subject of this thesis provides a detailed analysis of the VHE γ-ray data from the Galactic Center region observed by H.E.S.S. This was possible thanks to the deep exposure of this region, achieved by the H.E.S.S. experiment throughout the 2004-2011 period. The analysis and spectral

  15. SOLAR CONSTRAINTS ON ASYMMETRIC DARK MATTER

    International Nuclear Information System (INIS)

    Lopes, Ilídio; Silk, Joseph

    2012-01-01

    The dark matter content of the universe is likely to be a mixture of matter and antimatter, perhaps comparable to the measured asymmetric mixture of baryons and antibaryons. During the early stages of the universe, the dark matter particles are produced in a process similar to baryogenesis, and dark matter freezeout depends on the dark matter asymmetry and the annihilation cross section (s-wave and p-wave annihilation channels) of particles and antiparticles. In these η-parameterized asymmetric dark matter (ηADM) models, the dark matter particles have an annihilation cross section close to the weak interaction cross section, and a value of dark matter asymmetry η close to the baryon asymmetry η B . Furthermore, we assume that dark matter scattering of baryons, namely, the spin-independent scattering cross section, is of the same order as the range of values suggested by several theoretical particle physics models used to explain the current unexplained events reported in the DAMA/LIBRA, CoGeNT, and CRESST experiments. Here, we constrain ηADM by investigating the impact of such a type of dark matter on the evolution of the Sun, namely, the flux of solar neutrinos and helioseismology. We find that dark matter particles with a mass smaller than 15 GeV, a spin-independent scattering cross section on baryons of the order of a picobarn, and an η-asymmetry with a value in the interval 10 –12 -10 –10 , would induce a change in solar neutrino fluxes in disagreement with current neutrino flux measurements. This result is also confirmed by helioseismology data. A natural consequence of this model is suppressed annihilation, thereby reducing the tension between indirect and direct dark matter detection experiments, but the model also allows a greatly enhanced annihilation cross section. All the cosmological ηADM scenarios that we discuss have a relic dark matter density Ωh 2 and baryon asymmetry η B in agreement with the current WMAP measured values, Ω DM h 2 = 0

  16. SPE analysis of high efficiency PMTs for the DEAP-3600 dark matter detector

    International Nuclear Information System (INIS)

    Olsen, Kevin; Hallin, Aksel

    2011-01-01

    The Dark matter Experiment using Argon Pulse-shape discrimination is a collaborative effort to develop a next-generation, tonne-scale dark matter detector at SNOLAB. The detector will feature a single-phase liquid argon (LAr) target surrounded by an array of 266 photomultiplier tubes (PMTs). A new high-efficiency Hamamatsu R877-100 PMT has been delivered to the University of Alberta for evaluation by the DEAP collaboration. The increase in efficiency could lead to a much greater light yield, but other experiments have reported a slower rise time. We have placed the PMT in a small dark box and had a base and preamplifier designed to be used with either an oscilloscope or a multi-channel analyzer. With this setup we have demonstrated the PMT's ability to distinguish single photo-electrons (SPE) and characterized the PMT by measuring the SPE pulse height spectrum, the peak-to-valley ratio, the dark pulse rate, the baseline, time resolution and SPE efficiency for varying the high voltage supplied to the PMT.

  17. Constraints on the coupling between dark energy and dark matter from CMB data

    International Nuclear Information System (INIS)

    Murgia, R.; Gariazzo, S.; Fornengo, N.

    2016-01-01

    We investigate a phenomenological non-gravitational coupling between dark energy and dark matter, where the interaction in the dark sector is parameterized as an energy transfer either from dark matter to dark energy or the opposite. The models are constrained by a whole host of updated cosmological data: cosmic microwave background temperature anisotropies and polarization, high-redshift supernovae, baryon acoustic oscillations, redshift space distortions and gravitational lensing. Both models are found to be compatible with all cosmological observables, but in the case where dark matter decays into dark energy, the tension with the independent determinations of H 0 and σ 8 , already present for standard cosmology, increases: this model in fact predicts lower H 0 and higher σ 8 , mostly as a consequence of the higher amount of dark matter at early times, leading to a stronger clustering during the evolution. Instead, when dark matter is fed by dark energy, the reconstructed values of H 0 and σ 8 nicely agree with their local determinations, with a full reconciliation between high- and low-redshift observations. A non-zero coupling between dark energy and dark matter, with an energy flow from the former to the latter, appears therefore to be in better agreement with cosmological data

  18. Temperature dependence of dark current of pSi-n(Si2)1-x(CdS)x structures

    International Nuclear Information System (INIS)

    Usmonov, Sh.N.

    2007-01-01

    Full text: The research of influence of isovalent impurity on electric and photo-electric properties of semiconductors where formative with semiconductor continuous solid solutions (CSS) of substitution presents both the fundamental and the applied application interest at the area of material science and photoelectrical properties of semiconductors. In the given work results of experimental researches (Si 2 ) 1-x (CdS) x epitaxial layers grown on c-Si substrates by a method liquid phase epitaxy are presented. The grown layers had thickness and ∼ 10 micron, n-type of conductivity with specific resistance 0,016 Ohm sm. Dependences of the dark current of pSi-n(Si 2 ) 1-x (CdS) x structures have been investigated at various values of a bias voltage. In experiment it was observed anomaly dependence of current. The current with arising of temperature begun monotonously aroused and reached some minimal value at temperature 100 C and then again starts to arise up to temperature 200 C. Arising of dark current is caused of the band-to-band thermal generation of electron-hole pairs. The voltage drop at the temperature 100 C is caused by the recharging of impurity atoms CdS. It is known, that width of the forbidden band of CdS Eg,CdS=2,48 eV more than Eg,Si=1,1 eV. Covalent bond of atoms CdS is stronger than Si-Si bond. However, when the molecule of CdS replaces two atoms of silicon in tetrahedral lattice of silicon the bonds of Cd-S become weak under influence of surrounding atoms of silicon. It causes to occurrence impurity level CdS located on Ei=1,2 eV below a valence band top of silicon. The generation of electron-hole pairs with participation of CdS impurities at the 100 C temperature is occurred under action thermal phonons. However, holes formed on impurity levels are localized and they will be recombination centers. Therefore drop of the dark current caused by dispersion of carriers on impurity centers. (authors)

  19. Dark London: Dimensions and characteristics of dark tourism supply in the UK capital

    OpenAIRE

    Powell, Raymond; Iankova, Katia

    2016-01-01

    This paper will investigate the characteristics of the supply of dark tourism in London, UK through an examination of the identified main dark sites in London, UK. Our methodology is based on web analysis of the presence of marketed and non-marketed dark tourist sites in London, their web visitation, the level of their commercialisation and the characteristics which place them in the various scales as categorised in current literature, notably Stone (2006). We identified that London offers a ...

  20. Status of the PADME experiment and review of dark photon searches

    Directory of Open Access Journals (Sweden)

    Raggi M.

    2018-01-01

    Full Text Available While accelerator particle physics has traditionally focused on exploring dark matter through highenergy experiments, testing dark-sectors hypothesis requires innovative low energy experiments that use highintensity beams and high-sensitivity detectors. In this scenario attractive opportunities are offered to low energy machines and flavour experiments. In this paper we will focus our attention on the Dark Photon (DP scenario, reviewing the current status of searches and new opportunities with particular attention to the PADME experiment at Laboratori Nazionali di Frascati.

  1. Dark Matter Caustics

    International Nuclear Information System (INIS)

    Natarajan, Aravind

    2010-01-01

    The continuous infall of dark matter with low velocity dispersion in galactic halos leads to the formation of high density structures called caustics. Dark matter caustics are of two kinds : outer and inner. Outer caustics are thin spherical shells surrounding galaxies while inner caustics have a more complicated structure that depends on the dark matter angular momentum distribution. The presence of a dark matter caustic in the plane of the galaxy modifies the gas density in its neighborhood which may lead to observable effects. Caustics are also relevant to direct and indirect dark matter searches.

  2. Macro Dark Matter

    CERN Document Server

    Jacobs, David M; Lynn, Bryan W.

    2015-01-01

    Dark matter is a vital component of the current best model of our universe, $\\Lambda$CDM. There are leading candidates for what the dark matter could be (e.g. weakly-interacting massive particles, or axions), but no compelling observational or experimental evidence exists to support these particular candidates, nor any beyond-the-Standard-Model physics that might produce such candidates. This suggests that other dark matter candidates, including ones that might arise in the Standard Model, should receive increased attention. Here we consider a general class of dark matter candidates with characteristic masses and interaction cross-sections characterized in units of grams and cm$^2$, respectively -- we therefore dub these macroscopic objects as Macros. Such dark matter candidates could potentially be assembled out of Standard Model particles (quarks and leptons) in the early universe. A combination of earth-based, astrophysical, and cosmological observations constrain a portion of the Macro parameter space; ho...

  3. MAGNIFICATION AS A PROBE OF DARK MATTER HALOS AT HIGH REDSHIFTS

    International Nuclear Information System (INIS)

    Van Waerbeke, L.; Ford, J.; Milkeraitis, M.; Hildebrandt, H.

    2010-01-01

    We propose a new approach for measuring the mass profile of dark matter halos by stacking the lensing magnification of distant background galaxies behind groups and clusters of galaxies. The main advantage of lensing magnification is that, unlike lensing shear, it relies on accurate photometric redshifts only and not on galaxy shapes, thus enabling the study of the dark matter distribution with unresolved source galaxies. We present a feasibility study, using a real population of z ≥ 2.5 Lyman break galaxies as source galaxies, and where, similar to galaxy-galaxy lensing, foreground lenses are stacked in order to increase the signal-to-noise ratio. We find that there is an interesting new observational window for gravitational lensing as a probe of dark matter halos at high redshift, which does not require a measurement of galaxy shapes.

  4. Negative Offset Operation of Four-Transistor CMOS Image Pixels for Increased Well Capacity and Suppressed Dark Current

    NARCIS (Netherlands)

    Mheen, B.; Song, Y.J.; Theuwissen, J.P.

    2008-01-01

    This letter presents an electrical method to reduce dark current as well as increase well capacity of four-transistor pixels in a CMOS image sensor, utilizing a small negative offset voltage to the gate of the transfer (TX) transistor particularly only when the TX transistor is off. As a result,

  5. Search for Dark Photons with Accelerators

    Directory of Open Access Journals (Sweden)

    Merkel Harald

    2014-01-01

    Full Text Available A dark photon as the mediator of an interaction of the dark sector is a well motivated extension of the standard model. While possible dark matter particles are heavy and seem to be beyond the reach of current accelerators, the dark photon is not necessarily heavy and might have a mass in the range of existing accelerators. In recent years, an extensive experimental program at several accelerators for the search for dark photons were established. In this talk, recent results and progress in the determination of exclusion limits with accelerators is presented.

  6. Dark energy and dark matter

    International Nuclear Information System (INIS)

    Comelli, D.; Pietroni, M.; Riotto, A.

    2003-01-01

    It is a puzzle why the densities of dark matter and dark energy are nearly equal today when they scale so differently during the expansion of the universe. This conundrum may be solved if there is a coupling between the two dark sectors. In this Letter we assume that dark matter is made of cold relics with masses depending exponentially on the scalar field associated to dark energy. Since the dynamics of the system is dominated by an attractor solution, the dark matter particle mass is forced to change with time as to ensure that the ratio between the energy densities of dark matter and dark energy become a constant at late times and one readily realizes that the present-day dark matter abundance is not very sensitive to its value when dark matter particles decouple from the thermal bath. We show that the dependence of the present abundance of cold dark matter on the parameters of the model differs drastically from the familiar results where no connection between dark energy and dark matter is present. In particular, we analyze the case in which the cold dark matter particle is the lightest supersymmetric particle

  7. Tunneling effects in the current-voltage characteristics of high-efficiency GaAs solar cells

    Science.gov (United States)

    Kachare, R.; Anspaugh, B. E.; Garlick, G. F. J.

    1988-01-01

    Evidence is that tunneling via states in the forbidden gap is the dominant source of excess current in the dark current-voltage (I-V) characteristics of high-efficiency DMCVD grown Al(x)Ga(1-x)As/GaAs(x is equal to or greater than 0.85) solar cells. The dark forward and reverse I-V measurements were made on several solar cells, for the first time, at temperatures between 193 and 301 K. Low-voltage reverse-bias I-V data of a number of cells give a thermal activation energy for excess current of 0.026 + or - 0.005 eV, which corresponds to the carbon impurity in GaAs. However, other energy levels between 0.02 eV and 0.04 eV were observed in some cells which may correspond to impurity levels introduced by Cu, Si, Ge, or Cd. The forward-bias excess current is mainly due to carrier tunneling between localized levels created in the space-charge layer by impurities such as carbon, which are incorporated during the solar cell growth process. A model is suggested to explain the results.

  8. Epigenetic regulation of αA-crystallin in high myopia-induced dark nuclear cataract.

    Directory of Open Access Journals (Sweden)

    Xiang-Jia Zhu

    Full Text Available PURPOSE: To assess the etiology of early-onset dark nucleus in high-myopic patients and its relationship with the epigenetic regulation of αA-crystallin (CRYAA. METHODS: We reviewed clinical data from patients who underwent cataract surgery at our center in 2012. Lens epithelial samples were collected during capsulorhexis, whereas young lens epithelium was donated. Cataract type and severity were graded according to the Lens Opacity Classification System III (LOCS III. DNA methylation was analyzed by pyrosequencing the CpG islands of the CRYAA promoter in the following groups: Age-Related Cataract (ARC Nuclear Color (NC 2-3; High-Myopic Cataract (HMC NC2-3; ARC NC5-6; HMC NC5-6; and in young lenses graded NC1. We analyzed CRYAA expression by real-time polymerase chain reaction (PCR, reverse transcription PCR, and immunohistochemistry. RESULTS: The odds ratio of dark nucleus in high-myopic patients was 5.16 (95% confidence interval: 3.98-6.69; p<0.001. CpG islands in lens epithelial CRYAA promoter in the HMC NC5-6 Group exhibited the highest methylation of all the groups, but no statistically significant differences were evident between the HMC NC2-3 and ARC NC2-3 Groups. Likewise, CRYAA mRNA and protein levels in the HMC NC5-6 Group were significantly lower than the ARC NC5-6 Group and high-myopic controls. CONCLUSIONS: High myopia is a risk factor for dark nucleus. Downregulation of CRYAA via the hypermethylation of CpG islands in its promoter could underlie the earlier onset of dark nucleus in high-myopic patients.

  9. SOLAR CONSTRAINTS ON ASYMMETRIC DARK MATTER

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Ilidio [Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silk, Joseph, E-mail: ilidio.lopes@ist.utl.pt, E-mail: silk@astro.ox.ac.uk [Institut d' Astrophysique de Paris, F-75014 Paris (France)

    2012-10-01

    The dark matter content of the universe is likely to be a mixture of matter and antimatter, perhaps comparable to the measured asymmetric mixture of baryons and antibaryons. During the early stages of the universe, the dark matter particles are produced in a process similar to baryogenesis, and dark matter freezeout depends on the dark matter asymmetry and the annihilation cross section (s-wave and p-wave annihilation channels) of particles and antiparticles. In these {eta}-parameterized asymmetric dark matter ({eta}ADM) models, the dark matter particles have an annihilation cross section close to the weak interaction cross section, and a value of dark matter asymmetry {eta} close to the baryon asymmetry {eta}{sub B}. Furthermore, we assume that dark matter scattering of baryons, namely, the spin-independent scattering cross section, is of the same order as the range of values suggested by several theoretical particle physics models used to explain the current unexplained events reported in the DAMA/LIBRA, CoGeNT, and CRESST experiments. Here, we constrain {eta}ADM by investigating the impact of such a type of dark matter on the evolution of the Sun, namely, the flux of solar neutrinos and helioseismology. We find that dark matter particles with a mass smaller than 15 GeV, a spin-independent scattering cross section on baryons of the order of a picobarn, and an {eta}-asymmetry with a value in the interval 10{sup -12}-10{sup -10}, would induce a change in solar neutrino fluxes in disagreement with current neutrino flux measurements. This result is also confirmed by helioseismology data. A natural consequence of this model is suppressed annihilation, thereby reducing the tension between indirect and direct dark matter detection experiments, but the model also allows a greatly enhanced annihilation cross section. All the cosmological {eta}ADM scenarios that we discuss have a relic dark matter density {Omega}h {sup 2} and baryon asymmetry {eta}{sub B} in agreement with

  10. Review on Dark Photon

    Directory of Open Access Journals (Sweden)

    Curciarello Francesca

    2016-01-01

    Full Text Available e+e− collider experiments at the intensity frontier are naturally suited to probe the existence of a force beyond the Standard Model between WIMPs, the most viable dark matter candidates. The mediator of this new force, known as dark photon, should be a new vector gauge boson very weakly coupled to the Standard Model photon. No significant signal has been observed so far. I will report on current limits set on the coupling factor ε2 between the photon and the dark photon by e+e− collider experiments.

  11. Dark Energy and Structure Formation

    International Nuclear Information System (INIS)

    Singh, Anupam

    2010-01-01

    We study the gravitational dynamics of dark energy configurations. We report on the time evolution of the dark energy field configurations as well as the time evolution of the energy density to demonstrate the gravitational collapse of dark energy field configurations. We live in a Universe which is dominated by Dark Energy. According to current estimates about 75% of the Energy Density is in the form of Dark Energy. Thus when we consider gravitational dynamics and Structure Formation we expect Dark Energy to play an important role. The most promising candidate for dark energy is the energy density of fields in curved space-time. It therefore become a pressing need to understand the gravitational dynamics of dark energy field configurations. We develop and describe the formalism to study the gravitational collapse of fields given any general potential for the fields. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of space-time. Our results show that gravitational collapse of dark energy field configurations occurs and must be considered in any complete picture of our universe.

  12. Window in the dark matter exclusion limits

    International Nuclear Information System (INIS)

    Zaharijas, Gabrijela; Farrar, Glennys R.

    2005-01-01

    We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range

  13. Dark Matter Searches

    International Nuclear Information System (INIS)

    Moriyama, Shigetaka

    2008-01-01

    Recent cosmological as well as historical observations of rotational curves of galaxies strongly suggest the existence of dark matter. It is also widely believed that dark matter consists of unknown elementary particles. However, astrophysical observations based on gravitational effects alone do not provide sufficient information on the properties of dark matter. In this study, the status of dark matter searches is investigated by observing high-energy neutrinos from the sun and the earth and by observing nuclear recoils in laboratory targets. The successful detection of dark matter by these methods facilitates systematic studies of its properties. Finally, the XMASS experiment, which is due to start at the Kamioka Observatory, is introduced

  14. Late forming dark matter in theories of neutrino dark energy

    International Nuclear Information System (INIS)

    Das, Subinoy; Weiner, Neal

    2011-01-01

    We study the possibility of late forming dark matter, where a scalar field, previously trapped in a metastable state by thermal or finite density effects, goes through a phase transition near the era matter-radiation equality and begins to oscillate about its true minimum. Such a theory is motivated generally if the dark energy is of a similar form, but has not yet made the transition to dark matter, and, in particular, arises automatically in recently considered theories of neutrino dark energy. If such a field comprises the present dark matter, the matter power spectrum typically shows a sharp break at small, presently nonlinear scales, below which power is highly suppressed and previously contained acoustic oscillations. If, instead, such a field forms a subdominant component of the total dark matter, such acoustic oscillations may imprint themselves in the linear regime.

  15. Fault identification in crystalline silicon PV modules by complementary analysis of the light and dark current-voltage characteristics

    DEFF Research Database (Denmark)

    Spataru, Sergiu; Sera, Dezso; Hacke, Peter

    2016-01-01

    This article proposes a fault identification method, based on the complementary analysis of the light and dark current-voltage (I-V) characteristics of the photovoltaic (PV) module, to distinguish between four important degradation modes that lead to power loss in PV modules: (a) degradation of t...

  16. Results from the DarkSide-50 Dark Matter Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Alden [Univ. of California, Los Angeles, CA (United States)

    2016-01-01

    While there is tremendous astrophysical and cosmological evidence for dark matter, its precise nature is one of the most significant open questions in modern physics. Weakly interacting massive particles (WIMPs) are a particularly compelling class of dark matter candidates with masses of the order 100 GeV and couplings to ordinary matter at the weak scale. Direct detection experiments are aiming to observe the low energy (<100 keV) scattering of dark matter off normal matter. With the liquid noble technology leading the way in WIMP sensitivity, no conclusive signals have been observed yet. The DarkSide experiment is looking for WIMP dark matter using a liquid argon target in a dual-phase time projection chamber located deep underground at Gran Sasso National Laboratory (LNGS) in Italy. Currently filled with argon obtained from underground sources, which is greatly reduced in radioactive 39Ar, DarkSide-50 recently made the most sensitive measurement of the 39Ar activity in underground argon and used it to set the strongest WIMP dark matter limit using liquid argon to date. This work describes the full chain of analysis used to produce the recent dark matter limit, from reconstruction of raw data to evaluation of the final exclusion curve. The DarkSide- 50 apparatus is described in detail, followed by discussion of the low level reconstruction algorithms. The algorithms are then used to arrive at three broad analysis results: The electroluminescence signals in DarkSide-50 are used to perform a precision measurement of ii longitudinal electron diffusion in liquid argon. A search is performed on the underground argon data to identify the delayed coincidence signature of 85Kr decays to the 85mRb state, a crucial ingredient in the measurement of the 39Ar activity in the underground argon. Finally, a full description of the WIMP search is given, including development of cuts, efficiencies, energy scale, and exclusion

  17. On dark energy isocurvature perturbation

    International Nuclear Information System (INIS)

    Liu, Jie; Zhang, Xinmin; Li, Mingzhe

    2011-01-01

    Determining the equation of state of dark energy with astronomical observations is crucially important to understand the nature of dark energy. In performing a likelihood analysis of the data, especially of the cosmic microwave background and large scale structure data the dark energy perturbations have to be taken into account both for theoretical consistency and for numerical accuracy. Usually, one assumes in the global fitting analysis that the dark energy perturbations are adiabatic. In this paper, we study the dark energy isocurvature perturbation analytically and discuss its implications for the cosmic microwave background radiation and large scale structure. Furthermore, with the current astronomical observational data and by employing Markov Chain Monte Carlo method, we perform a global analysis of cosmological parameters assuming general initial conditions for the dark energy perturbations. The results show that the dark energy isocurvature perturbations are very weakly constrained and that purely adiabatic initial conditions are consistent with the data

  18. Make dark matter charged again

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub, E-mail: prateekagrawal@fas.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: randall@physics.harvard.edu, E-mail: jscholtz@physics.harvard.edu [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)

    2017-05-01

    We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.

  19. Indirect searches for dark matter

    Indian Academy of Sciences (India)

    The current status of indirect searches for dark matter has been reviewed in a schematic way here. The main relevant experimental results of the recent years have been listed and the excitements and disappointments that their phenomenological interpretations in terms of almost-standard annihilating dark matter have ...

  20. Bayesian evidences for dark energy models in light of current observational data

    Science.gov (United States)

    Lonappan, Anto. I.; Kumar, Sumit; Ruchika; Dinda, Bikash R.; Sen, Anjan A.

    2018-02-01

    We do a comprehensive study of the Bayesian evidences for a large number of dark energy models using a combination of latest cosmological data from SNIa, CMB, BAO, strong lensing time delay, growth measurements, measurements of Hubble parameter at different redshifts and measurements of angular diameter distance by Megamaser Cosmology Project. We consider a variety of scalar field models with different potentials as well as different parametrizations for the dark energy equation of state. Among 21 models that we consider in our study, we do not find strong evidences in favor of any evolving dark energy model compared to Λ CDM . For the evolving dark energy models, we show that purely nonphantom models have much better evidences compared to those models that allow both phantom and nonphantom behaviors. Canonical scalar field with exponential and tachyon field with square potential have highest evidences among all the models considered in this work. We also show that a combination of low redshift measurements decisively favors an accelerating Λ CDM model compared to a nonaccelerating power law model.

  1. Dark matter and dark forces from a supersymmetric hidden sector

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, S.; Goodsell, M.D.; Ringwald, A.

    2011-09-15

    We show that supersymmetric ''Dark Force'' models with gravity mediation are viable. To this end, we analyse a simple supersymmetric hidden sector model that interacts with the visible sector via kinetic mixing of a light Abelian gauge boson with the hypercharge. We include all induced interactions with the visible sector such as neutralino mass mixing and the Higgs portal term. We perform a detailed parameter space scan comparing the produced dark matter relic abundance and direct detection cross-sections to current experiments. (orig.)

  2. On the capture of dark matter by neutron stars

    International Nuclear Information System (INIS)

    Güver, Tolga; Erkoca, Arif Emre; Sarcevic, Ina; Reno, Mary Hall

    2014-01-01

    We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 10 3 GeV/cm 3 and dark matter mass m χ ∼< 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m χ ∼ 10 GeV when the dark matter interaction cross section with the nucleons ranges from σ χn ∼ 10 −52 cm 2 to σ χn ∼ 10 −57 cm 2 , the dark matter self-interaction cross section limit is σ χχ ∼< 10 −33 cm 2 , which is about ten orders of magnitude stronger than the Bullet Cluster limit

  3. Anisotropic dark matter distribution functions and impact on WIMP direct detection

    International Nuclear Information System (INIS)

    Bozorgnia, Nassim; Schwetz, Thomas; Catena, Riccardo

    2013-01-01

    Dark matter N-body simulations suggest that the velocity distribution of dark matter is anisotropic. In this work we employ a mass model for the Milky Way whose parameters are determined from a fit to kinematical data. Then we adopt an ansatz for the dark matter phase space distribution which allows to construct self-consistent halo models which feature a degree of anisotropy as a function of the radius such as suggested by the simulations. The resulting velocity distributions are then used for an analysis of current data from dark matter direct detection experiments. We find that velocity distributions which are radially biased at large galactocentric distances (up to the virial radius) lead to an increased high velocity tail of the local dark matter distribution. This affects the interpretation of data from direct detection experiments, especially for dark matter masses around 10 GeV, since in this region the high velocity tail is sampled. We find that the allowed regions in the dark matter mass-cross section plane as indicated by possible hints for a dark matter signal reported by several experiments as well as conflicting exclusion limits from other experiments shift in a similar way when the halo model is varied. Hence, it is not possible to improve the consistency of the data by referring to anisotropic halo models of the type considered in this work

  4. Dark-matter QCD-axion searches.

    Science.gov (United States)

    Rosenberg, Leslie J

    2015-10-06

    In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There's no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10(-(6-3)) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments

  5. Searching dark matter at LHC

    International Nuclear Information System (INIS)

    Nojiri, Mihoko M.

    2007-01-01

    We now believe that the dark matter in our Universe must be an unknown elementary particle, which is charge neutral and weakly interacting. The standard model must be extended to include it. The dark matter was likely produced in the early universe from the high energy collisions of the particles. Now LHC experiment starting from 2008 will create such high energy collision to explore the nature of the dark matter. In this article we explain how dark matter and LHC physics will be connected in detail. (author)

  6. On dark matter selected high-scale supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Sibo [Department of Physics, Chongqing University,Chongqing 401331 (China)

    2015-03-11

    The prediction for the Higgs mass in the dark matter selected high-scale SUSY is explored. We show the bounds on SUSY-breaking scale in models of SM +w-tilde and SM +h-tilde/s-tilde due to the observed Higgs mass at the LHC. We propose that effective theory below scale m-tilde described by SM +w-tilde is possibly realized in gauge mediation with multiple spurion fields that exhibit significant mass hierarchy, and that by SM +h-tilde/s-tilde can be realized with direct singlet-messenger-messenger coupling for singlet Yukawa coupling λ∼(v/m-tilde){sup 1/2}g{sub SM}. Finally, the constraint on high-scale SUSY is investigated in the light of inflation physics if these two subjects are directly related.

  7. Interactions between dark energy and dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Marco

    2009-03-20

    We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with {lambda}{sub CDM}. Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the {lambda}{sub CDM} model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter

  8. Interactions between dark energy and dark matter

    International Nuclear Information System (INIS)

    Baldi, Marco

    2009-01-01

    We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with Λ CDM . Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the Λ CDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios

  9. Asymmetric dark matter

    International Nuclear Information System (INIS)

    Kaplan, David E.; Luty, Markus A.; Zurek, Kathryn M.

    2009-01-01

    We consider a simple class of models in which the relic density of dark matter is determined by the baryon asymmetry of the Universe. In these models a B-L asymmetry generated at high temperatures is transferred to the dark matter, which is charged under B-L. The interactions that transfer the asymmetry decouple at temperatures above the dark matter mass, freezing in a dark matter asymmetry of order the baryon asymmetry. This explains the observed relation between the baryon and dark matter densities for the dark matter mass in the range 5-15 GeV. The symmetric component of the dark matter can annihilate efficiently to light pseudoscalar Higgs particles a or via t-channel exchange of new scalar doublets. The first possibility allows for h 0 →aa decays, while the second predicts a light charged Higgs-like scalar decaying to τν. Direct detection can arise from Higgs exchange in the first model or a nonzero magnetic moment in the second. In supersymmetric models, the would-be lightest supersymmetric partner can decay into pairs of dark matter particles plus standard model particles, possibly with displaced vertices.

  10. Dark energy constraints from the cosmic age and supernova

    International Nuclear Information System (INIS)

    Feng Bo; Wang Xiulian; Zhang Xinmin

    2005-01-01

    Using the low limit of cosmic ages from globular cluster and the white dwarfs: t 0 >12Gyr, together with recent new high redshift supernova observations from the HST/GOODS program and previous supernova data, we give a considerable estimation of the equation of state for dark energy, with uniform priors as weak as 0.2 m m h 2 <0.16. We find cosmic age limit plays a significant role in lowering the upper bound on the variation amplitude of dark energy equation of state. We propose in this Letter a new scenario of dark energy dubbed quintom, which gives rise to the equation of state larger than -1 in the past and less than -1 today, satisfying current observations. In addition we have also considered the implications of recent X-ray gas mass fraction data on dark energy, which favors a negative running of the equation of state

  11. Directly detecting isospin-violating dark matter

    Science.gov (United States)

    Kelso, Chris; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

    2018-03-01

    We consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. We focus on theoretically well-motivated examples of isospin-violating dark matter (IVDM), including models in which dark matter interactions with nuclei are mediated by a dark photon, a Z , or a squark. We determine that the best prospects for distinguishing IVDM from the isospin-invariant scenario arise in the cases of dark photon-or Z -mediated interactions, and that the ideal experimental scenario would consist of large exposure xenon- and neon-based detectors. If such models just evade current direct detection limits, then one could distinguish such models from the standard isospin-invariant case with two detectors with of order 100 ton-year exposure.

  12. Comparing holographic dark energy models with statefinder

    International Nuclear Information System (INIS)

    Cui, Jing-Lei; Zhang, Jing-Fei

    2014-01-01

    We apply the statefinder diagnostic to the holographic dark energy models, including the original holographic dark energy (HDE) model, the new holographic dark energy model, the new agegraphic dark energy (NADE) model, and the Ricci dark energy model. In the low-redshift region the holographic dark energy models are degenerate with each other and with the ΛCDM model in the H(z) and q(z) evolutions. In particular, the HDE model is highly degenerate with the ΛCDM model, and in the HDE model the cases with different parameter values are also in strong degeneracy. Since the observational data are mainly within the low-redshift region, it is very important to break this lowredshift degeneracy in the H(z) and q(z) diagnostics by using some quantities with higher order derivatives of the scale factor. It is shown that the statefinder diagnostic r(z) is very useful in breaking the low-redshift degeneracies. By employing the statefinder diagnostic the holographic dark energy models can be differentiated efficiently in the low-redshift region. The degeneracy between the holographic dark energy models and the ΛCDM model can also be broken by this method. Especially for the HDE model, all the previous strong degeneracies appearing in the H(z) and q(z) diagnostics are broken effectively. But for the NADE model, the degeneracy between the cases with different parameter values cannot be broken, even though the statefinder diagnostic is used. A direct comparison of the holographic dark energy models in the r-s plane is also made, in which the separations between the models (including the ΛCDM model) can be directly measured in the light of the current values {r 0 , s 0 } of the models. (orig.)

  13. Dark Higgs bosons at the ForwArd Search ExpeRiment

    Science.gov (United States)

    Feng, Jonathan L.; Galon, Iftah; Kling, Felix; Trojanowski, Sebastian

    2018-03-01

    FASER, ForwArd Search ExpeRiment at the LHC, has been proposed as a small, very far forward detector to discover new, light, weakly-coupled particles. Previous work showed that with a total volume of just ˜0.1 - 1 m3 , FASER can discover dark photons in a large swath of currently unconstrained parameter space, extending the discovery reach of the LHC program. Here we explore FASER's discovery prospects for dark Higgs bosons. These scalar particles are an interesting foil for dark photons, as they probe a different renormalizable portal interaction and are produced dominantly through B and K meson decays, rather than pion decays, leading to less collimated signals. Nevertheless, we find that FASER is also a highly sensitive probe of dark Higgs bosons with significant discovery prospects that are comparable to, and complementary to, much larger proposed experiments.

  14. The case for a directional dark matter detector and the status of current experimental efforts

    CERN Document Server

    Ahlen, S; Battat, J B R; Billard, J; Bozorgnia, N; Burgos, S; Caldwell, T; Carmona, J M; Cebrián, S; Colas, P; Dafni, T; Daw, E; Dujmic, D; Dushkin, A; Fedus, W; Ferrer, E; Finkbeiner, D; Fisher, P H; Forbes, J; Fusayasu, T; Galan, J; Gamble, T; Ghag, C; Giomataris, Yu; Gold, M; Gomez, H; Gómez, M E; Gondolo, P; Green, A; Grignon, C; Guillaudin, O; Hagemann, C; Hattori, K; Henderson, S; Higashi, N; Ida, C; Iguaz, F J; Inglis, A; Irastorza, I G; Iwaki, S; Kaboth, A; Kabuki, S; Kadyk, J; Kallivayalil, N; Kubo, H; Kurosawa, S; Kudryavtsev, V A; Lamy, T; Lanza, R; Lawson, T B; Lee, A; Lee, E R; Lin, T; Loomba, D; López, J; Luzón, G; Manobu, T; Martoff, J; Mayet, F; McCluskey, B; Miller, E; Miuchi, K; Monroe, J; Morgan, B; Muna, D; Murphy, A St J; Naka, T; Nakamura, K; Nakamura, M; Nakano, T; Nicklin, G G; Nishimura, H; Niwa, K; Paling, S M; Parker, J; Petkov, A; Pipe, M; Pushkin, K; Robinson, M; Rodríguez, A; Rodríguez-Quintero, J; Sahin, T; Sanderson, R; Sanghi, N; Santos, D; Sato, O; Sawano, T; Sciolla, G; Sekiya, H; Slatyer, T R; Snowden-Ifft, D P; Spooner, N J C; Sugiyama, A; Takada, A; Takahashi, M; Takeda, A; Tanimori, T; Taniue, K; Tomas, A; Tomita, H; Tsuchiya, K; Turk, J; Tziaferi, E; Ueno, K; Vahsen, S; Vanderspek, R; Vergados, J; Villar, J A; Wellenstein, H; Wolfe, I; Yamamoto, R K; Yegoryan, H

    2010-01-01

    We present the case for a dark matter detector with directional sensitivity. This document was developed at the 2009 CYGNUS workshop on directional dark matter detection, and contains contributions from theorists and experimental groups in the field. We describe the need for a dark matter detector with directional sensitivity; each directional dark matter experiment presents their project's status; and we close with a feasibility study for scaling up to a one ton directional detector, which would cost around $150M.

  15. Status and Results from DarkSide-50

    OpenAIRE

    Fan, Alden; Collaboration, for the DarkSide

    2015-01-01

    DarkSide-50 is the first physics detector of the DarkSide dark matter search program. The detector features a dual-phase underground-argon Time Projection Chamber (TPC) of 50 kg active mass surrounded by an organic liquid-scintillator neutron veto (30 tons) and a water-Cherenkov muon detector (1000 tons). The TPC is currently fully shielded and operating underground at Gran Sasso National Laboratory. A first run of 1422 kg-day exposure with atmospheric argon represents the most sensitive dark...

  16. Focus point in dark matter selected high-scale supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Sibo [Department of Physics, Chongqing University,Chongqing, 401331 P.R. (China)

    2015-03-19

    In this paper, we explore conditions for focus point in the high-scale supersymmetry with the weak-scale gaugino masses. In this context the tension between the naturalness and LHC 2013 data about supersymmetry as well as the cold dark matter candidate are addressed simultaneously. It is shown that the observed Higgs mass can be satisfied in a wide classes of new models, which are realized by employing the non-minimal gauge mediation.

  17. Dark matter and the equivalence principle

    Science.gov (United States)

    Frieman, Joshua A.; Gradwohl, Ben-Ami

    1993-01-01

    A survey is presented of the current understanding of dark matter invoked by astrophysical theory and cosmology. Einstein's equivalence principle asserts that local measurements cannot distinguish a system at rest in a gravitational field from one that is in uniform acceleration in empty space. Recent test-methods for the equivalence principle are presently discussed as bases for testing of dark matter scenarios involving the long-range forces between either baryonic or nonbaryonic dark matter and ordinary matter.

  18. Probing sub-GeV dark matter-baryon scattering with cosmological observables

    Science.gov (United States)

    Xu, Weishuang Linda; Dvorkin, Cora; Chael, Andrew

    2018-05-01

    We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝vn , where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ˜MeV . We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

  19. Exponential Potential versus Dark Matter

    Science.gov (United States)

    1993-10-15

    scale of the solar system. Galaxy, Dark matter , Galaxy cluster, Gravitation, Quantum gravity...A two parameter exponential potential explains the anomalous kinematics of galaxies and galaxy clusters without need for the myriad ad hoc dark ... matter models currently in vogue. It also explains much about the scales and structures of galaxies and galaxy clusters while being quite negligible on the

  20. Paths to dark energy theory and observation

    CERN Document Server

    Valtonen, Mauri; Chernin, Arthur D; Byrd, Gene

    2012-01-01

    This work provides the current theory and observations behind the cosmological phenomenon of dark energy. The approach is comprehensivewith rigorous mathematical theory and relevant astronomical observations discussed in context.The book treats the background and history starting with the new-found importance of Einstein's cosmological constant (proposed long ago for the opposite purpose) in dark energy formulation, as well as the frontiers of dark energy.

  1. Enlightening Students about Dark Matter

    Science.gov (United States)

    Hamilton, Kathleen; Barr, Alex; Eidelman, Dave

    2018-01-01

    Dark matter pervades the universe. While it is invisible to us, we can detect its influence on matter we can see. To illuminate this concept, we have created an interactive javascript program illustrating predictions made by six different models for dark matter distributions in galaxies. Students are able to match the predicted data with actual experimental results, drawn from several astronomy papers discussing dark matter’s impact on galactic rotation curves. Programming each new model requires integration of density equations with parameters determined by nonlinear curve-fitting using MATLAB scripts we developed. Using our javascript simulation, students can determine the most plausible dark matter models as well as the average percentage of dark matter lurking in galaxies, areas where the scientific community is still continuing to research. In that light, we strive to use the most up-to-date and accepted concepts: two of our dark matter models are the pseudo-isothermal halo and Navarro-Frenk-White, and we integrate out to each galaxy’s virial radius. Currently, our simulation includes NGC3198, NGC2403, and our own Milky Way.

  2. Search for Dark Matter at ATLAS

    CERN Document Server

    Conventi, Francesco; The ATLAS collaboration

    2017-01-01

    Dark Matter composes almost 25% of our Universe, but its identity is still unknown which makes it a large challenge for current fundamental physics. A lot of approaches are used to discover the identity of Dark Matter and one of them, collider searches, are discussed in this talk. The latest results on Dark Matter search at ATLAS using 2015 and 2016 data are presented. Results from searches for new physics in the events with final states containing large missing transverse energy + X (photons, jets, boson) are shown. Higgs to invisible and dijet searches are used in sense of complementarity to constrain properties of Dark Matter.

  3. Dynamical evolution of quintessence dark energy in collapsing dark matter halos

    International Nuclear Information System (INIS)

    Wang Qiao; Fan Zuhui

    2009-01-01

    In this paper, we analyze the dynamical evolution of quintessence dark energy induced by the collapse of dark matter halos. Different from other previous studies, we develop a numerical strategy which allows us to calculate the dark energy evolution for the entire history of the spherical collapse of dark matter halos, without the need of separate treatments for linear, quasilinear, and nonlinear stages of the halo formation. It is found that the dark energy perturbations evolve with redshifts, and their specific behaviors depend on the quintessence potential as well as the collapsing process. The overall energy density perturbation is at the level of 10 -6 for cluster-sized halos. The perturbation amplitude decreases with the decrease of the halo mass. At a given redshift, the dark energy perturbation changes with the radius to the halo center, and can be either positive or negative depending on the contrast of ∂ t φ, ∂ r φ, and φ with respect to the background, where φ is the quintessence field. For shells where the contrast of ∂ r φ is dominant, the dark energy perturbation is positive and can be as high as about 10 -5 .

  4. The detector for dark matter search

    International Nuclear Information System (INIS)

    Li Jin

    2004-01-01

    The dark matter search and dark matter detection is very importance project in Particle Physics, Astrophysics and Cosmology. The paper introduces the current status of the dark matter search in the world and points out that the development of detector with larger scale, lower threshold, very low radioactive background and building of underground laboratory is important developing direction. So far, there is no such detector and underground laboratory in our county. We should change such situation as soon as possible. (authors)

  5. Novel dark matter phenomenology at colliders

    Science.gov (United States)

    Wardlow, Kyle Patrick

    While a suitable candidate particle for dark matter (DM) has yet to be discovered, it is possible one will be found by experiments currently investigating physics on the weak scale. If discovered on that energy scale, the dark matter will likely be producible in significant quantities at colliders like the LHC, allowing the properties of and underlying physical model characterizing the dark matter to be precisely determined. I assume that the dark matter will be produced as one of the decay products of a new massive resonance related to physics beyond the Standard Model, and using the energy distributions of the associated visible decay products, develop techniques for determining the symmetry protecting these potential dark matter candidates from decaying into lighter Standard Model (SM) particles and to simultaneously measure the masses of both the dark matter candidate and the particle from which it decays.

  6. How to distinguish dark energy and modified gravity?

    International Nuclear Information System (INIS)

    Wei Hao; Zhang Shuangnan

    2008-01-01

    The current accelerated expansion of our universe could be due to an unknown energy component (dark energy) or a modification of general relativity (modified gravity). In the literature it has been proposed that combining the probes of the cosmic expansion history and growth history can distinguish between dark energy and modified gravity. In this work, without invoking nontrivial dark energy clustering, we show that the possible interaction between dark energy and dark matter could make the interacting dark model and the modified gravity model indistinguishable. An explicit example is also given. Therefore, it is required to seek some complementary probes beyond the ones of cosmic expansion history and growth history.

  7. An ecological approach to problems of Dark Energy, Dark Matter, MOND and Neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Zhao HongSheng [Scottish University Physics Alliance, University of St Andrews, KY16 8SB (United Kingdom); Sterrewacht Leiden, PO Box 9513, 2300 RA Leiden (Netherlands)], E-mail: hz4@st-andrews.ac.uk

    2008-11-01

    Modern astronomical data on galaxy and cosmological scales have revealed powerfully the existence of certain dark sectors of fundamental physics, i.e., existence of particles and fields outside the standard models and inaccessible by current experiments. Various approaches are taken to modify/extend the standard models. Generic theories introduce multiple de-coupled fields A, B, C, each responsible for the effects of DM (cold supersymmetric particles), DE (Dark Energy) effect, and MG (Modified Gravity) effect respectively. Some theories use adopt vanilla combinations like AB, BC, or CA, and assume A, B, C belong to decoupled sectors of physics. MOND-like MG and Cold DM are often taken as antagnising frameworks, e.g. in the muddled debate around the Bullet Cluster. Here we argue that these ad hoc divisions of sectors miss important clues from the data. The data actually suggest that the physics of all dark sectors is likely linked together by a self-interacting oscillating field, which governs a chameleon-like dark fluid, appearing as DM, DE and MG in different settings. It is timely to consider an interdisciplinary approach across all semantic boundaries of dark sectors, treating the dark stress as one identity, hence accounts for several 'coincidences' naturally.

  8. High order dark wavefront sensing simulations

    Science.gov (United States)

    Ragazzoni, Roberto; Arcidiacono, Carmelo; Farinato, Jacopo; Viotto, Valentina; Bergomi, Maria; Dima, Marco; Magrin, Demetrio; Marafatto, Luca; Greggio, Davide; Carolo, Elena; Vassallo, Daniele

    2016-07-01

    Dark wavefront sensing takes shape following quantum mechanics concepts in which one is able to "see" an object in one path of a two-arm interferometer using an as low as desired amount of light actually "hitting" the occulting object. A theoretical way to achieve such a goal, but in the realm of wavefront sensing, is represented by a combination of two unequal beams interferometer sharing the same incoming light, and whose difference in path length is continuously adjusted in order to show different signals for different signs of the incoming perturbation. Furthermore, in order to obtain this in white light, the path difference should be properly adjusted vs the wavelength used. While we incidentally describe how this could be achieved in a true optomechanical setup, we focus our attention to the simulation of a hypothetical "perfect" dark wavefront sensor of this kind in which white light compensation is accomplished in a perfect manner and the gain is selectable in a numerical fashion. Although this would represent a sort of idealized dark wavefront sensor that would probably be hard to match in the real glass and metal, it would also give a firm indication of the maximum achievable gain or, in other words, of the prize for achieving such device. Details of how the simulation code works and first numerical results are outlined along with the perspective for an in-depth analysis of the performances and its extension to more realistic situations, including various sources of additional noise.

  9. Current Observational Constraints to Holographic Dark Energy Model with New Infrared cut-off via Markov Chain Monte Carlo Method

    OpenAIRE

    Wang, Yuting; Xu, Lixin

    2010-01-01

    In this paper, the holographic dark energy model with new infrared (IR) cut-off for both the flat case and the non-flat case are confronted with the combined constraints of current cosmological observations: type Ia Supernovae, Baryon Acoustic Oscillations, current Cosmic Microwave Background, and the observational hubble data. By utilizing the Markov Chain Monte Carlo (MCMC) method, we obtain the best fit values of the parameters with $1\\sigma, 2\\sigma$ errors in the flat model: $\\Omega_{b}h...

  10. Dark matter that can form dark stars

    International Nuclear Information System (INIS)

    Gondolo, Paolo; Huh, Ji-Haeng; Kim, Hyung Do; Scopel, Stefano

    2010-01-01

    The first stars to form in the Universe may be powered by the annihilation of weakly interacting dark matter particles. These so-called dark stars, if observed, may give us a clue about the nature of dark matter. Here we examine which models for particle dark matter satisfy the conditions for the formation of dark stars. We find that in general models with thermal dark matter lead to the formation of dark stars, with few notable exceptions: heavy neutralinos in the presence of coannihilations, annihilations that are resonant at dark matter freeze-out but not in dark stars, some models of neutrinophilic dark matter annihilating into neutrinos only and lighter than about 50 GeV. In particular, we find that a thermal DM candidate in standard Cosmology always forms a dark star as long as its mass is heavier than ≅ 50 GeV and the thermal average of its annihilation cross section is the same at the decoupling temperature and during the dark star formation, as for instance in the case of an annihilation cross section with a non-vanishing s-wave contribution

  11. Proton irradiation experiment for x-ray charge-coupled devices of the monitor of all-sky x-ray image mission onboard the international space station. 2. Degradation of dark current and identification of electron trap level

    CERN Document Server

    Miyata, E; Kamiyama, D

    2003-01-01

    We have investigated the radiation damage effects on a charge-coupled device (CCD) to be used for the Japanese X-ray mission, the monitor of all-sky X-ray image (MAXI), onboard the international space station (ISS). A temperature dependence of the dark current as a function of incremental dose is studied. We found that the protons having energy of >292 keV seriously increased the dark current of the devices. In order to improve the radiation tolerance of the devices, we have developed various device architectures to minimize the radiation damage in orbit. Among them, nitride oxide enables us to reduce the dark current significantly and therefore we adopted nitride oxide for the flight devices. We also compared the dark current of a device in operation and that out of operation during the proton irradiation. The dark current of the device in operation became twofold that out of operation, and we thus determined that devices would be turned off during the passage of the radiation belt. The temperature dependenc...

  12. Dark Energy. What the ...?

    Energy Technology Data Exchange (ETDEWEB)

    Wechsler, Risa

    2007-10-30

    What is the Universe made of? This question has been asked as long as humans have been questioning, and astronomers and physicists are finally converging on an answer. The picture which has emerged from numerous complementary observations over the past decade is a surprising one: most of the matter in the Universe isn't visible, and most of the Universe isn't even made of matter. In this talk, I will explain what the rest of this stuff, known as 'Dark Energy' is, how it is related to the so-called 'Dark Matter', how it impacts the evolution of the Universe, and how we can study the dark universe using observations of light from current and future telescopes.

  13. Particle dark matter constraints from the Draco dwarf galaxy

    International Nuclear Information System (INIS)

    Tyler, Craig

    2002-01-01

    It is widely thought that neutralinos, the lightest supersymmetric particles, could comprise most of the dark matter. If so, then dark halos will emit radio and gamma ray signals initiated by neutralino annihilation. A particularly promising place to look for these indicators is at the center of the local group dwarf spheroidal galaxy Draco, and recent measurements of the motion of its stars have revealed it to be an even better target for dark matter detection than previously thought. We compute limits on WIMP properties for various models of Draco's dark matter halo. We find that if the halo is nearly isothermal, as the new measurements indicate, then current gamma ray flux limits prohibit much of the neutralino parameter space. If Draco has a moderate magnetic field, then current radio limits can rule out more of it. These results are appreciably stronger than other current constraints, and so acquiring more detailed data on Draco's density profile may become one of the most promising avenues for identifying dark matter

  14. Decaying dark matter from dark instantons

    International Nuclear Information System (INIS)

    Carone, Christopher D.; Erlich, Joshua; Primulando, Reinard

    2010-01-01

    We construct an explicit, TeV-scale model of decaying dark matter in which the approximate stability of the dark matter candidate is a consequence of a global symmetry that is broken only by instanton-induced operators generated by a non-Abelian dark gauge group. The dominant dark matter decay channels are to standard model leptons. Annihilation of the dark matter to standard model states occurs primarily through the Higgs portal. We show that the mass and lifetime of the dark matter candidate in this model can be chosen to be consistent with the values favored by fits to data from the PAMELA and Fermi-LAT experiments.

  15. HIGH-ENERGY PARTICLES FLUX ORIGIN IN THE CLOUDS, DARK LIGHTNING

    Directory of Open Access Journals (Sweden)

    Kuznetsov, V.V.

    2016-11-01

    Full Text Available Problem of high-energy particles flux origin in clouds is discussed. Conditions in which dark lightning preceding the ordinary one and creating additional ionization, fluxes of fast electrons with MeV energy prior to the earthquake detected among lightning initiating ball-lightning, glow, sprites are considered. All above phenomena appear to be of general nature founded on quantum entanglement of hydrogen bonds protons in water clasters inside clouds.

  16. Effect of high current density to defect generation of blue LED and its characterization with transmission electron microscope

    Science.gov (United States)

    Gunawan, R.; Sugiarti, E.; Isnaeni; Purawiardi, R. I.; Widodo, H.; Muslimin, A. N.; Yuliasari; Ronaldus, C. E.; Prastomo, N.; Hastuty, S.

    2018-03-01

    The optical, electrical and structural characteristics of InGaN-based blue light-emitting diodes (LEDs) were investigated to identify the degradation of LED before and after current injection. The sample was injected by high current of 200 A/cm2 for 5 and 20 minutes. It was observed that injection of current shifts light intensity and wavelength characteristics that indicated defect generation. Transmission Electron Microscopy (TEM) characterization was carried out in order to clarify the structure degradation caused by defect in active layer which consisted of 14 quantum well with thickness of about 5 nm and confined with barrier layer with thickness of about 12 nm. TEM results showed pre-existing defect in LED before injection with high current. Furthermore, discontinue and edge defect was found in dark spot region of LED after injection with high current.

  17. Astronomical Signatures of Dark Matter

    Directory of Open Access Journals (Sweden)

    Paul Gorenstein

    2014-01-01

    Full Text Available Several independent astronomical observations in different wavelength bands reveal the existence of much larger quantities of matter than what we would deduce from assuming a solar mass to light ratio. They are very high velocities of individual galaxies within clusters of galaxies, higher than expected rotation rates of stars in the outer regions of galaxies, 21 cm line studies indicative of increasing mass to light ratios with radius in the halos of spiral galaxies, hot gaseous X-ray emitting halos around many elliptical galaxies, and clusters of galaxies requiring a much larger component of unseen mass for the hot gas to be bound. The level of gravitational attraction needed for the spatial distribution of galaxies to evolve from the small perturbations implied by the very slightly anisotropic cosmic microwave background radiation to its current web-like configuration requires much more mass than is observed across the entire electromagnetic spectrum. Distorted shapes of galaxies and other features created by gravitational lensing in the images of many astronomical objects require an amount of dark matter consistent with other estimates. The unambiguous detection of dark matter and more recently evidence for dark energy has positioned astronomy at the frontier of fundamental physics as it was in the 17th century.

  18. Kinetic k-essence ghost dark energy model

    International Nuclear Information System (INIS)

    Rozas-Fernández, Alberto

    2012-01-01

    A ghost dark energy model has been recently put forward to explain the current accelerated expansion of the Universe. In this model, the energy density of ghost dark energy, which comes from the Veneziano ghost of QCD, is proportional to the Hubble parameter, ρ D =αH. Here α is a constant of order Λ QCD 3 where Λ QCD ∼100 MeV is the QCD mass scale. We consider a connection between ghost dark energy with/without interaction between the components of the dark sector and the kinetic k-essence field. It is shown that the cosmological evolution of the ghost dark energy dominated Universe can be completely described a kinetic k-essence scalar field. We reconstruct the kinetic k-essence function F(X) in a flat Friedmann-Robertson-Walker Universe according to the evolution of ghost dark energy density.

  19. Probing neutrino dark energy with extremely high-energy cosmic neutrinos

    International Nuclear Information System (INIS)

    Ringwald, A.; Schrempp, L.

    2006-06-01

    Recently, a new non-Standard Model neutrino interaction mediated by a light scalar field was proposed, which renders the big-bang relic neutrinos of the cosmic neutrino background a natural dark energy candidate, the so-called Neutrino Dark Energy. As a further consequence of this interaction, the neutrino masses become functions of the neutrino energy densities and are thus promoted to dynamical, time/redshift dependent quantities. Such a possible neutrino mass variation introduces a redshift dependence into the resonance energies associated with the annihilation of extremely high-energy cosmic neutrinos on relic anti-neutrinos and vice versa into Z-bosons. In general, this annihilation process is expected to lead to sizeable absorption dips in the spectra to be observed on earth by neutrino observatories operating in the relevant energy region above 10 13 GeV. In our analysis, we contrast the characteristic absorption features produced by constant and varying neutrino masses, including all thermal background effects caused by the relic neutrino motion. We firstly consider neutrinos from astrophysical sources and secondly neutrinos originating from the decomposition of topological defects using the appropriate fragmentation functions. On the one hand, independent of the nature of neutrino masses, our results illustrate the discovery potential for the cosmic neutrino background by means of relic neutrino absorption spectroscopy. On the other hand, they allow to estimate the prospects for testing its possible interpretation as source of Neutrino Dark Energy within the next decade by the neutrino observatories ANITA and LOFAR. (Orig.)

  20. Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

    International Nuclear Information System (INIS)

    Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora

    2017-01-01

    The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N fluid , will be improved by an order of magnitude compared to current bounds.

  1. Evaluation of Dark Spots Formated on the High Temperature Metal Filter Elements

    International Nuclear Information System (INIS)

    Park, Seung Chul; Hwang, Tae Won; Moon, Chan Kook

    2008-01-01

    Metal filter elements were newly introduced to the high temperature filter (HTF) system in the low- and intermediate-level radioactive waste vitrification plant. In order to evaluate the performance of various metal materials as filter media, elements made of AISI 316L, AISI 904L, and Inconel 600 were included to the test set of filter elements. At the visual inspection to the elements performed after completion of each test, a few dark spots were observed on the surface of some elements. Especially they were found much more at the AISI 316L elements than others. To check the dark spots are the corrosion phenomena or not, two kinds of analyses were performed to the tested filter elements. Firstly, the surfaces or the cross sections of filter specimens cut out from both normal area and dark spot area of elements were analyzed by SEM/EDS. The results showed that the dark spots were not evidences of corrosion but the deposition of sodium, sulfur and silica compounds volatilized from waste or molten glass. Secondly, the ring tensile strength were analyzed for the ring-shape filter specimens cut out from each kind of element. The result obtained from the strength tested showed no evidence of corrosion as well. Conclusionally, depending on the two kinds of analysis, no evidences of corrosion were found at the tested metal filter elements. But the dark spots formed on the surface could reduce the effective filtering area and increase the overall pressure drop of HTF system. Thus, continuous heating inside filter housing up to dew point will be required normally. And a few long-period test should be followed for the exact evaluation of corrosion of the metal filter elements.

  2. Simulated Milky Way analogues: implications for dark matter direct searches

    Science.gov (United States)

    Bozorgnia, Nassim; Calore, Francesca; Schaller, Matthieu; Lovell, Mark; Bertone, Gianfranco; Frenk, Carlos S.; Crain, Robert A.; Navarro, Julio F.; Schaye, Joop; Theuns, Tom

    2016-05-01

    We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the EAGLE and APOSTLE projects. We identify Milky Way analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best fit Maxwellian distribution (with peak speed of 223-289 km/s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved.

  3. Dark matter directional detection in non-relativistic effective theories

    International Nuclear Information System (INIS)

    Catena, Riccardo

    2015-01-01

    We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF 4 , CS 2 and 3 He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments

  4. Exceptional composite dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros, Guillermo [Universite Paris Saclay, CEA, CNRS, Institut de Physique Theorique, Gif-sur-Yvette (France); Carmona, Adrian [CERN, Theoretical Physics Department, Geneva (Switzerland); Chala, Mikael [Universitat de Valencia y IFIC, Universitat de Valencia-CSIC, Departament de Fisica Teorica, Burjassot, Valencia (Spain)

    2017-07-15

    We study the dark matter phenomenology of non-minimal composite Higgs models with SO(7) broken to the exceptional group G{sub 2}. In addition to the Higgs, three pseudo-Nambu-Goldstone bosons arise, one of which is electrically neutral. A parity symmetry is enough to ensure this resonance is stable. In fact, if the breaking of the Goldstone symmetry is driven by the fermion sector, this Z{sub 2} symmetry is automatically unbroken in the electroweak phase. In this case, the relic density, as well as the expected indirect, direct and collider signals are then uniquely determined by the value of the compositeness scale, f. Current experimental bounds allow one to account for a large fraction of the dark matter of the Universe if the dark matter particle is part of an electroweak triplet. The totality of the relic abundance can be accommodated if instead this particle is a composite singlet. In both cases, the scale f and the dark matter mass are of the order of a few TeV. (orig.)

  5. Dark energy and dark matter from hidden symmetry of gravity model with a non-Riemannian volume form

    Energy Technology Data Exchange (ETDEWEB)

    Guendelman, Eduardo [Ben-Gurion University of the Negev, Department of Physics, Beersheba (Israel); Nissimov, Emil; Pacheva, Svetlana [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria)

    2015-10-15

    We show that dark energy and dark matter can be described simultaneously by ordinary Einstein gravity interacting with a single scalar field provided the scalar field Lagrangian couples in a symmetric fashion to two different spacetime volume forms (covariant integration measure densities) on the spacetime manifold - one standard Riemannian given by √(-g) (square root of the determinant of the pertinent Riemannian metric) and another non-Riemannian volume form independent of the Riemannian metric, defined in terms of an auxiliary antisymmetric tensor gauge field of maximal rank. Integration of the equations of motion of the latter auxiliary gauge field produce an a priori arbitrary integration constant that plays the role of a dynamically generated cosmological constant or dark energy. Moreover, the above modified scalar field action turns out to possess a hidden Noether symmetry whose associated conserved current describes a pressureless ''dust'' fluid which we can identify with the dark matter completely decoupled from the dark energy. The form of both the dark energy and dark matter that results from the above class of models is insensitive to the specific form of the scalar field Lagrangian. By adding an appropriate perturbation, which breaks the above hidden symmetry and along with this couples dark matter and dark energy, we also suggest a way to obtain growing dark energy in the present universe's epoch without evolution pathologies. (orig.)

  6. Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

    Energy Technology Data Exchange (ETDEWEB)

    Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora, E-mail: rkrall@physics.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: dvorkin@physics.harvard.edu [Harvard University, Department of Physics, Cambridge, MA 02138 (United States)

    2017-09-01

    The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N {sub fluid}, will be improved by an order of magnitude compared to current bounds.

  7. Composite Dark Sectors

    International Nuclear Information System (INIS)

    Carmona, Adrian

    2015-06-01

    We introduce a new paradigm in Composite Dark Sectors, where the full Standard Model (including the Higgs boson) is extended with a strongly-interacting composite sector with global symmetry group G spontaneously broken to H is contained in G. We show that, under well-motivated conditions, the lightest neutral pseudo Nambu-Goldstone bosons are natural dark matter candidates for they are protected by a parity symmetry not even broken in the electroweak phase. These models are characterized by only two free parameters, namely the typical coupling g D and the scale f D of the composite sector, and are therefore very predictive. We consider in detail two minimal scenarios, SU(3)/[SU(2) x U(1)] and [SU(2) 2 x U(1)]/[SU(2) x U(1)], which provide a dynamical realization of the Inert Doublet and Triplet models, respectively. We show that the radiatively-induced potential can be computed in a five-dimensional description with modified boundary conditions with respect to Composite Higgs models. Finally, the dark matter candidates are shown to be compatible, in a large region of the parameter space, with current bounds from dark matter searches as well as electroweak and collider constraints on new resonances.

  8. Dark matter and dark energy: The critical questions

    International Nuclear Information System (INIS)

    Michael S. Turner

    2002-01-01

    Stars account for only about 0.5% of the content of the Universe; the bulk of the Universe is optically dark. The dark side of the Universe is comprised of: at least 0.1% light neutrinos; 3.5% ± 1% baryons; 29% ± 4% cold dark matter; and 66% ± 6% dark energy. Now that we have characterized the dark side of the Universe, the challenge is to understand it. The critical questions are: (1) What form do the dark baryons take? (2) What is (are) the constituent(s) of the cold dark matter? (3) What is the nature of the mysterious dark energy that is causing the Universe to speed up

  9. Probing leptophilic dark sectors with hadronic processes

    Science.gov (United States)

    D'Eramo, Francesco; Kavanagh, Bradley J.; Panci, Paolo

    2017-08-01

    We study vector portal dark matter models where the mediator couples only to leptons. In spite of the lack of tree-level couplings to colored states, radiative effects generate interactions with quark fields that could give rise to a signal in current and future experiments. We identify such experimental signatures: scattering of nuclei in dark matter direct detection; resonant production of lepton-antilepton pairs at the Large Hadron Collider; and hadronic final states in dark matter indirect searches. Furthermore, radiative effects also generate an irreducible mass mixing between the vector mediator and the Z boson, severely bounded by ElectroWeak Precision Tests. We use current experimental results to put bounds on this class of models, accounting for both radiatively induced and tree-level processes. Remarkably, the former often overwhelm the latter.

  10. Dark Dark Wood

    DEFF Research Database (Denmark)

    2017-01-01

    2017 student Bachelor film. Synopsis: Young princess Maria has had about enough of her royal life – it’s all lesson, responsibilities and duties on top of each other, every hour of every day. Overwhelmed Maria is swept away on an adventure into the monster-filled dark, dark woods. During 2017...

  11. Modeling radiation loads in the ILC main linac and a novel approach to treat dark current

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, Nilolai V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Rakhno, Igor L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Tropin, Igor S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2017-09-11

    Electromagnetic and hadron showers generated by electrons of dark current (DC) can represent a significant radiation threat to the ILC linac equipment and personnel. In this study, a commissioning scenario is analysed which is considered as the worst-case scenario for the main linac regarding the DC contribution to the radiation environment in the tunnel. A normal operation scenario is analysed as well. An emphasis is made on radiation load to sensitive electronic equipment—cryogenic thermometers inside the cryomodules. Prompt and residual dose rates in the ILC main linac tunnels were also calculated in these new high-statistics runs. A novel approach was developed—as a part of general purpose Monte Carlo code MARS15—to model generation, acceleration and transport of DC electrons in electromagnetic fields inside SRF cavities. Comparisons were made with a standard approach when a set of pre-calculated DC electron trajectories is used, with a proper normalization, as a source for Monte Carlo modelling. Results of MARS15 Monte Carlo calculations, performed for the current main linac tunnel design, reveal that the peak absorbed dose in the cryogenic thermometers in the main tunnel for 20 years of operation is about 0.8 MGy. The calculated contact residual dose on cryomodules and tunnel walls in the main tunnel for typical irradiation and cooling conditions is 0.1 and 0.01 mSv/hr, respectively.

  12. Self-Destructing Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, Yuval [Cornell U., LEPP; Harnik, Roni [Fermilab; Telem, Ofri [Cornell U., LEPP; Zhang, Yue [Northwestern U.

    2017-12-01

    We present Self-Destructing Dark Matter (SDDM), a new class of dark matter models which are detectable in large neutrino detectors. In this class of models, a component of dark matter can transition from a long-lived state to a short-lived one by scattering off of a nucleus or an electron in the Earth. The short-lived state then decays to Standard Model particles, generating a dark matter signal with a visible energy of order the dark matter mass rather than just its recoil. This leads to striking signals in large detectors with high energy thresholds. We present a few examples of models which exhibit self destruction, all inspired by bound state dynamics in the Standard Model. The models under consideration exhibit a rich phenomenology, possibly featuring events with one, two, or even three lepton pairs, each with a fixed invariant mass and a fixed energy, as well as non-trivial directional distributions. This motivates dedicated searches for dark matter in large underground detectors such as Super-K, Borexino, SNO+, and DUNE.

  13. Interacting dark sector and precision cosmology

    Science.gov (United States)

    Buen-Abad, Manuel A.; Schmaltz, Martin; Lesgourgues, Julien; Brinckmann, Thejs

    2018-01-01

    We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data (H0-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between ΛCDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (σ8-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full k-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over ΛCDM at 3–4 σ. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.

  14. Modified dark matter: Relating dark energy, dark matter and baryonic matter

    Science.gov (United States)

    Edmonds, Douglas; Farrah, Duncan; Minic, Djordje; Ng, Y. Jack; Takeuchi, Tatsu

    Modified dark matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics. For an accelerating universe with positive cosmological constant (Λ), such phenomenological considerations lead to the emergence of a critical acceleration parameter related to Λ. Such a critical acceleration is an effective phenomenological manifestation of MDM, and it is found in correlations between dark matter and baryonic matter in galaxy rotation curves. The resulting MDM mass profiles, which are sensitive to Λ, are consistent with observational data at both the galactic and cluster scales. In particular, the same critical acceleration appears both in the galactic and cluster data fits based on MDM. Furthermore, using some robust qualitative arguments, MDM appears to work well on cosmological scales, even though quantitative studies are still lacking. Finally, we comment on certain nonlocal aspects of the quanta of modified dark matter, which may lead to novel nonparticle phenomenology and which may explain why, so far, dark matter detection experiments have failed to detect dark matter particles.

  15. One dark matter mystery: halos in the cosmic web

    International Nuclear Information System (INIS)

    Gaite, Jose

    2015-01-01

    The current cold dark matter cosmological model explains the large scale cosmic web structure but is challenged by the observation of a relatively smooth distribution of matter in galactic clusters. We consider various aspects of modeling the dark matter around galaxies as distributed in smooth halos and, especially, the smoothness of the dark matter halos seen in N-body cosmological simulations. We conclude that the problems of the cold dark matter cosmology on small scales are more serious than normally admitted

  16. One dark matter mystery: halos in the cosmic web

    Science.gov (United States)

    Gaite, Jose

    2015-01-01

    The current cold dark matter cosmological model explains the large scale cosmic web structure but is challenged by the observation of a relatively smooth distribution of matter in galactic clusters. We consider various aspects of modeling the dark matter around galaxies as distributed in smooth halos and, especially, the smoothness of the dark matter halos seen in N-body cosmological simulations. We conclude that the problems of the cold dark matter cosmology on small scales are more serious than normally admitted.

  17. Simplified phenomenology for colored dark sectors

    Energy Technology Data Exchange (ETDEWEB)

    Hedri, Sonia El; Kaminska, Anna; Vries, Maikel de [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,55099 Mainz (Germany); Zurita, Jose [Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology,Engesserstraße 7, D-76128 Karlsruhe (Germany)

    2017-04-20

    We perform a general study of the relic density and LHC constraints on simplified models where the dark matter coannihilates with a strongly interacting particle X. In these models, the dark matter depletion is driven by the self-annihilation of X to pairs of quarks and gluons through the strong interaction. The phenomenology of these scenarios therefore only depends on the dark matter mass and the mass splitting between dark matter and X as well as the quantum numbers of X. In this paper, we consider simplified models where X can be either a scalar, a fermion or a vector, as well as a color triplet, sextet or octet. We compute the dark matter relic density constraints taking into account Sommerfeld corrections and bound state formation. Furthermore, we examine the restrictions from thermal equilibrium, the lifetime of X and the current and future LHC bounds on X pair production. All constraints are comprehensively presented in the mass splitting versus dark matter mass plane. While the relic density constraints can lead to upper bounds on the dark matter mass ranging from 2 TeV to more than 10 TeV across our models, the prospective LHC bounds range from 800 to 1500 GeV. A full coverage of the strongly coannihilating dark matter parameter space would therefore require hadron colliders with significantly higher center-of-mass energies.

  18. Observational constraints on dark energy and cosmic curvature

    International Nuclear Information System (INIS)

    Wang Yun; Mukherjee, Pia

    2007-01-01

    Current observational bounds on dark energy depend on our assumptions about the curvature of the universe. We present a simple and efficient method for incorporating constraints from cosmic microwave background (CMB) anisotropy data and use it to derive constraints on cosmic curvature and dark energy density as a free function of cosmic time using current CMB, Type Ia supernova (SN Ia), and baryon acoustic oscillation data. We show that there are two CMB shift parameters, R≡√(Ω m H 0 2 )r(z CMB ) (the scaled distance to recombination) and l a ≡πr(z CMB )/r s (z CMB ) (the angular scale of the sound horizon at recombination), with measured values that are nearly uncorrelated with each other. Allowing nonzero cosmic curvature, the three-year WMAP (Wilkinson Microwave Anisotropy Probe) data give R=1.71±0.03, l a =302.5±1.2, and Ω b h 2 =0.02173±0.00082, independent of the dark energy model. The corresponding bounds for a flat universe are R=1.70±0.03, l a =302.2±1.2, and Ω b h 2 =0.022±0.00082. We give the covariance matrix of (R,l a ,Ω b h 2 ) from the three-year WMAP data. We find that (R,l a ,Ω b h 2 ) provide an efficient and intuitive summary of CMB data as far as dark energy constraints are concerned. Assuming the Hubble Space Telescope (HST) prior of H 0 =72±8 (km/s) Mpc -1 , using 182 SNe Ia (from the HST/GOODS program, the first year Supernova Legacy Survey, and nearby SN Ia surveys), (R,l a ,Ω b h 2 ) from WMAP three-year data, and SDSS (Sloan Digital Sky Survey) measurement of the baryon acoustic oscillation scale, we find that dark energy density is consistent with a constant in cosmic time, with marginal deviations from a cosmological constant that may reflect current systematic uncertainties or true evolution in dark energy. A flat universe is allowed by current data: Ω k =-0.006 -0.012-0.025 +0.013+0.025 for assuming that the dark energy equation of state w X (z) is constant, and Ω k =-0.002 -0.018-0.032 +0.018+0.041 for w X (z

  19. Vector dark energy and high-z massive clusters

    Science.gov (United States)

    Carlesi, Edoardo; Knebe, Alexander; Yepes, Gustavo; Gottlöber, Stefan; Jiménez, Jose Beltrán.; Maroto, Antonio L.

    2011-12-01

    The detection of extremely massive clusters at z > 1 such as SPT-CL J0546-5345, SPT-CL J2106-5844 and XMMU J2235.3-2557 has been considered by some authors as a challenge to the standard Λ cold dark matter cosmology. In fact, assuming Gaussian initial conditions, the theoretical expectation of detecting such objects is as low as ≤1 per cent. In this paper we discuss the probability of the existence of such objects in the light of the vector dark energy paradigm, showing by means of a series of N-body simulations that chances of detection are substantially enhanced in this non-standard framework.

  20. Interaction in the dark sector

    Science.gov (United States)

    del Campo, Sergio; Herrera, Ramón; Pavón, Diego

    2015-06-01

    It may well happen that the two main components of the dark sector of the Universe, dark matter and dark energy, do not evolve separately but interact nongravitationally with one another. However, given our current lack of knowledge of the microscopic nature of these two components, there is no clear theoretical path to determine their interaction. Yet, over the years, phenomenological interaction terms have been proposed on mathematical simplicity and heuristic arguments. In this paper, based on the likely evolution of the ratio between the energy densities of these dark components, we lay down reasonable criteria to obtain phenomenological, useful, expressions of the said term independent of any gravity theory. We illustrate this with different proposals which seem compatible with the known evolution of the Universe at the background level. Likewise, we show that two possible degeneracies with noninteracting models are only apparent as they can be readily broken at the background level. Further, we analyze some interaction terms that appear in the literature.

  1. Toward a minimum branching fraction for dark matter annihilation into electromagnetic final states

    International Nuclear Information System (INIS)

    Dent, James B.; Scherrer, Robert J.; Weiler, Thomas J.

    2008-01-01

    Observational limits on the high-energy neutrino background have been used to place general constraints on dark matter that annihilates only into standard model particles. Dark matter particles that annihilate into neutrinos will also inevitably branch into electromagnetic final states through higher-order tree and loop diagrams that give rise to charged leptons, and these charged particles can transfer their energy into photons via synchrotron radiation or inverse Compton scattering. In the context of effective field theory, we calculate the loop-induced branching ratio to charged leptons and show that it is generally quite large, typically > or approx. 1%, when the scale of the dark matter mass exceeds the electroweak scale, M W . For a branching fraction >or approx. 3%, the synchrotron radiation bounds on dark matter annihilation are currently stronger than the corresponding neutrino bounds in the interesting mass range from 100 GeV to 1 TeV. For dark matter masses below M W , our work provides a plausible framework for the construction of a model for 'neutrinos-only' dark matter annihilations.

  2. The mystery of dark matter

    International Nuclear Information System (INIS)

    Khalatbari, Azar

    2015-01-01

    As only 0.5 per cent (the shining part) of the Universe is seen by telescopes, and corresponds to a tenth of ordinary matter or 5 per cent of the cosmos, astrophysicists postulated that the remaining 95 per cent are made of dark matter and dark energy. But always more researchers put the existence of this dark matter and energy into question again. They notably think of giving up Newton's law of universal gravitation, and also the basic assumption of cosmology, i.e. the homogeneous character of the Universe. The article recalls the emergence of the notion of dark matter to explain the fact that stars stay within a galaxy, whereas with their observed speed and the application of the gravitational theory they should escape their galaxy. Then, the issue has been to find evidence of the existence of dark matter. Neutrinos were supposed to be a clue, but only for a while. The notion of dark energy was introduced more recently by researchers who, by the observation of supernovae, noticed that the Universe expansion was accelerated in time. Then, after having discussed the issues raised by the possible existence of dark energy, the article explains how and why a new non homogeneous cosmology emerged. It also evokes current and future researches in this field. In an interview, an astrophysicist outlines why we should dare to modify Newton's law

  3. Dark energy observational evidence and theoretical models

    CERN Document Server

    Novosyadlyj, B; Shtanov, Yu; Zhuk, A

    2013-01-01

    The book elucidates the current state of the dark energy problem and presents the results of the authors, who work in this area. It describes the observational evidence for the existence of dark energy, the methods and results of constraining of its parameters, modeling of dark energy by scalar fields, the space-times with extra spatial dimensions, especially Kaluza---Klein models, the braneworld models with a single extra dimension as well as the problems of positive definition of gravitational energy in General Relativity, energy conditions and consequences of their violation in the presence of dark energy. This monograph is intended for science professionals, educators and graduate students, specializing in general relativity, cosmology, field theory and particle physics.

  4. Dark Matter searches with the ATLAS Detector

    CERN Document Server

    Suchek, Stanislav; The ATLAS collaboration

    2017-01-01

    Dark Matter composes almost 25% of our Universe, but its identity is still unknown which makes it a large challenge for current fundamental physics. A lot of approaches are used to discover the identity of Dark Matter and one of them, collider searches, are discussed in this talk. The latest results on Dark Matter search at ATLAS using 2015 and 2016 data are presented. Results from searches for new physics in the events with final states containing large missing transverse energy and a single photon or Higgs boson are shown. Higgs to invisible and dijet searches are used in sense of complementarity to constrain properties of Dark Matter. Results and perspectives for all these searches are presented.

  5. DarkSide-50, a background free experiment for dark matter searches

    International Nuclear Information System (INIS)

    Bossa, M

    2014-01-01

    The existence of dark matter is inferred from gravitational effects, but its nature remains a deep mystery. One possibility, motivated by considerations in elementary particle physics, is that dark matter consists of elementary particles, such as the hypothesized Weakly Interacting Massive Particles (WIMPs), with mass ∼ 100 GeV and cross-section ∼ 10 −47 cm 2 , that can be gravitationally trapped inside our galaxy and revealed by their scattering on nuclei. It should be possible to detect WIMPs directly, as the orbital motion of the WIMPs composing the dark matter halo pervading the galaxy should result in WIMP-nucleus collisions of sufficient energy to be observable in the laboratory. The DarkSide-50 experiment is a direct WIMP search using a Liquid Argon Time Projection Chamber (LAr-TPC) with an active mass of 50 kg with a high sensitivity and an ultra-low background detector

  6. Cold dark matter: Controversies on small scales.

    Science.gov (United States)

    Weinberg, David H; Bullock, James S; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H G

    2015-10-06

    The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way's dwarf galaxy satellites. We review the current observational and theoretical status of these "small-scale controversies." Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years.

  7. Interacting dark matter disguised as warm dark matter

    International Nuclear Information System (INIS)

    Boehm, Celine; Riazuelo, Alain; Hansen, Steen H.; Schaeffer, Richard

    2002-01-01

    We explore some of the consequences of dark-matter-photon interactions on structure formation, focusing on the evolution of cosmological perturbations and performing both an analytical and a numerical study. We compute the cosmic microwave background anisotropies and matter power spectrum in this class of models. We find, as the main result, that when dark matter and photons are coupled, dark matter perturbations can experience a new damping regime in addition to the usual collisional Silk damping effect. Such dark matter particles (having quite large photon interactions) behave like cold dark matter or warm dark matter as far as the cosmic microwave background anisotropies or matter power spectrum are concerned, respectively. These dark-matter-photon interactions leave specific imprints at sufficiently small scales on both of these two spectra, which may allow us to put new constraints on the acceptable photon-dark-matter interactions. Under the conservative assumption that the abundance of 10 12 M · galaxies is correctly given by the cold dark matter, and without any knowledge of the abundance of smaller objects, we obtain the limit on the ratio of the dark-matter-photon cross section to the dark matter mass σ γ-DM /m DM -6 σ Th /(100 GeV)≅6x10 -33 cm 2 GeV -1

  8. Dark fluid: A complex scalar field to unify dark energy and dark matter

    International Nuclear Information System (INIS)

    Arbey, Alexandre

    2006-01-01

    In this article, we examine a model which proposes a common explanation for the presence of additional attractive gravitational effects - generally considered to be due to dark matter - in galaxies and in clusters, and for the presence of a repulsive effect at cosmological scales - generally taken as an indication of the presence of dark energy. We therefore consider the behavior of a so-called dark fluid based on a complex scalar field with a conserved U(1)-charge and associated to a specific potential, and show that it can at the same time account for dark matter in galaxies and in clusters, and agree with the cosmological observations and constraints on dark energy and dark matter

  9. Origins and challenges of viral dark matter.

    Science.gov (United States)

    Krishnamurthy, Siddharth R; Wang, David

    2017-07-15

    The accurate classification of viral dark matter - metagenomic sequences that originate from viruses but do not align to any reference virus sequences - is one of the major obstacles in comprehensively defining the virome. Depending on the sample, viral dark matter can make up from anywhere between 40 and 90% of sequences. This review focuses on the specific nature of dark matter as it relates to viral sequences. We identify three factors that contribute to the existence of viral dark matter: the divergence and length of virus sequences, the limitations of alignment based classification, and limited representation of viruses in reference sequence databases. We then discuss current methods that have been developed to at least partially circumvent these limitations and thereby reduce the extent of viral dark matter. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Updated constraints on the dark matter interpretation of CDMS-II-Si data

    International Nuclear Information System (INIS)

    Witte, Samuel J.; Gelmini, Graciela B.

    2017-01-01

    We present an updated halo-dependent and halo-independent analysis of viable light WIMP dark matter candidates which could account for the excess observed in CDMS-II-Si. We include recent constraints from LUX, PandaX-II, and PICO-60, as well as projected sensitivities for XENON1T, SuperCDMS SNOLAB, LZ, DARWIN, DarkSide-20k, and PICO-250, on candidates with spin-independent isospin conserving and isospin-violating interactions, and either elastic or exothermic scattering. We show that there exist dark matter candidates which can explain the CDMS-II-Si data and remain very marginally consistent with the null results of all current experiments, however such models are highly tuned, making a dark matter interpretation of CDMS-II-Si very unlikely. We find that these models can only be ruled out in the future by an experiment comparable to LZ or PICO-250.

  11. Dark Mass Creation During EWPT Via Dark Energy Interaction

    OpenAIRE

    Kisslinger, Leonard S.; Casper, Steven

    2013-01-01

    We add Dark Matter Dark Energy terms with a quintessence field interacting with a Dark Matter field to a MSSM EW Lagrangian previously used to calculate the magnetic field created during the EWPT. From the expectation value of the quintessence field we estimate the Dark Matter mass for parameters used in previous work on Dark Matter-Dark Energy interactions.

  12. Fundamentalist physics: why Dark Energy is bad for astronomy

    International Nuclear Information System (INIS)

    White, Simon D M

    2007-01-01

    Astronomers carry out observations to explore the diverse processes and objects which populate our Universe. High-energy physicists carry out experiments to approach the Fundamental Theory underlying space, time and matter. Dark Energy is a unique link between them, reflecting deep aspects of the Fundamental Theory, yet apparently accessible only through astronomical observation. Large sections of the two communities have therefore converged in support of astronomical projects to constrain Dark Energy. In this essay I argue that this convergence can be damaging for astronomy. The two communities have different methodologies and different scientific cultures. By uncritically adopting the values of an alien system, astronomers risk undermining the foundations of their own current success and endangering the future vitality of their field. Dark Energy is undeniably an interesting problem to tackle through astronomical observation, but it is one of many and not necessarily the one where significant progress is most likely to follow a major investment of resources

  13. High-theabrownins instant dark tea product by Aspergillus niger via submerged fermentation: α-glucosidase and pancreatic lipase inhibition and antioxidant activity.

    Science.gov (United States)

    Wang, Yuwan; Zhang, Mingyue; Zhang, Zhengzhu; Lu, Hengqian; Gao, Xueling; Yue, Pengxiang

    2017-12-01

    Theabrownins (TB) are bioactive components that are usually extracted from Chinese dark tea, in which they are present at low concentrations. The present study aimed to produce an instant dark tea high in theabrownins via submerged fermentation by the fungus Aspergillus niger. Three fermentation parameters that affect theabrownins content (i.e. inoculum size, liquid-solid ratio and rotation speed) were optimized using response surface methodology. Optimum fermentation conditions were modeled to be an inoculum of 5.40% (v/v), a liquid-solid ratio of 27.45 mL g -1 and a rotation speed of 184 rpm and were predicted to yield 292.99 g kg -1 TB. Under these experimentally conditions, the TB content of the instant dark tea was 291.93 g kg -1 . The antioxidant capacity and α-glucosidase and pancreatic lipase inhibitory activities of the high-TB instant black tea were higher than four other typical instant dark tea products. The results of the present study show that careful management of culture conditions can produce a dark tea high in theabrownins. Furthermore, high-theabrownins instant dark tea could serve as a source of bioactive products and be used in functional foods as an ingredient imparting antioxidant properties and the ability to inhibit pancreatic lipase and α-glucosidase. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  14. ADMX Dark-Matter Axion Search

    International Nuclear Information System (INIS)

    Rosenberg, Leslie J.

    2004-01-01

    The axion, a hypothetical elementary particle, emerged from a compelling solution to the Strong-CP Problem in QCD. Subsequently, the axion was recognized to be a good Cold Dark Matter candidate. Although dark-matter axions have only feeble couplings to matter and radiation, these axions may be detected through resonant conversion of axions into microwave photons in a high-Q cavity threaded by a strong static magnetic field. This technique is at present the only means whereby dark-matter axions with plausible couplings may be detected at the required sensitivity. This talk describes recent results from the Axion Dark Matter Experiment (ADMX), now the world's most sensitive search for axions. There will also be a short overview of the ADMX upgrade, which promises sensitivity to even the more feebly coupled dark matter axions even should they make up only a minority fraction of the local dark matter halo

  15. Ricci-Gauss-Bonnet holographic dark energy

    Science.gov (United States)

    Saridakis, Emmanuel N.

    2018-03-01

    We present a model of holographic dark energy in which the infrared cutoff is determined by both the Ricci and the Gauss-Bonnet invariants. Such a construction has the significant advantage that the infrared cutoff, and consequently the holographic dark energy density, does not depend on the future or the past evolution of the universe, but only on its current features, and moreover it is determined by invariants, whose role is fundamental in gravitational theories. We extract analytical solutions for the behavior of the dark energy density and equation-of-state parameters as functions of the redshift. These reveal the usual thermal history of the universe, with the sequence of radiation, matter and dark energy epochs, resulting in the future to a complete dark energy domination. The corresponding dark energy equation-of-state parameter can lie in the quintessence or phantom regime, or experience the phantom-divide crossing during the cosmological evolution, and its asymptotic value can be quintessencelike, phantomlike, or be exactly equal to the cosmological-constant value. Finally, we extract the constraints on the model parameters that arise from big bang nucleosynthesis.

  16. Dark matter as a weakly coupled dark baryon

    Science.gov (United States)

    Mitridate, Andrea; Redi, Michele; Smirnov, Juri; Strumia, Alessandro

    2017-10-01

    Dark Matter might be an accidentally stable baryon of a new confining gauge interaction. We extend previous studies exploring the possibility that the DM is made of dark quarks heavier than the dark confinement scale. The resulting phenomenology contains new unusual elements: a two-stage DM cosmology (freeze-out followed by dark condensation), a large DM annihilation cross section through recombination of dark quarks (allowing to fit the positron excess). Light dark glue-balls are relatively long lived and give extra cosmological effects; DM itself can remain radioactive.

  17. Secular evolution of galaxies and galaxy clusters in decaying dark matter cosmology

    International Nuclear Information System (INIS)

    Ferrer, Francesc; Nipoti, Carlo; Ettori, Stefano

    2009-01-01

    If the dark matter sector in the Universe is composed by metastable particles, galaxies and galaxy clusters are expected to undergo significant secular evolution from high to low redshift. We show that the decay of dark matter, with a lifetime compatible with cosmological constraints, can be at the origin of the observed evolution of the Tully-Fisher relation of disk galaxies and alleviate the problem of the size evolution of elliptical galaxies, while being consistent with the current observational constraints on the gas fraction of clusters of galaxies.

  18. The dark triad: Emotional and interpersonal characteristics

    Directory of Open Access Journals (Sweden)

    Tomić Katarina N.

    2016-01-01

    Full Text Available The Dark triad is a construct of pathological personality traits, which consists of three components conceptually different, but still with significant empirical overlap: narcissism, Machiavellianism and subclinical psychopathy. The concept of Dark Triad found its place in the current structural models of personality, such as the Big-five and HEXACO model, and also an Interpersonal circumplex, within which the personal qualities project itselves into certain patterns of interpersonal behavior. This paper provides a brief theoretical overview of the basic elements of the Dark Triad, and an overview of current research related to (un justified observation of the three constituent dimensions as a single construct in theoretical and empirical terms. Also, the paper presents an overview of the emotional dysfunctions typical for the triad, as well as the problems and consequences in the area of interpersonal and social relations.

  19. Dark interactions and cosmological fine-tuning

    Energy Technology Data Exchange (ETDEWEB)

    Quartin, Miguel; Calvao, Mauricio O; Joras, Sergio E; Reis, Ribamar R R; Waga, Ioav, E-mail: mquartin@if.ufrj.br, E-mail: orca@if.ufrj.br, E-mail: joras@if.ufrj.br, E-mail: ribamar@if.ufrj.br, E-mail: ioav@if.ufrj.br [Instituto de Fisica, Universidade Federal do Rio de Janeiro, CEP 21941-972, Rio de Janeiro, RJ (Brazil)

    2008-05-15

    Cosmological models involving an interaction between dark matter and dark energy have been proposed in order to solve the so-called coincidence problem. Different forms of coupling have been studied, but there have been claims that observational data seem to narrow (some of) them down to something annoyingly close to the {Lambda}CDM (CDM: cold dark matter) model, thus greatly reducing their ability to deal with the problem in the first place. The smallness problem of the initial energy density of dark energy has also been a target of cosmological models in recent years. Making use of a moderately general coupling scheme, this paper aims to unite these different approaches and shed some light on whether this class of models has any true perspective in suppressing the aforementioned issues that plague our current understanding of the universe, in a quantitative and unambiguous way.

  20. Exponentially Light Dark Matter from Coannihilation

    OpenAIRE

    D'Agnolo, Raffaele Tito; Mondino, Cristina; Ruderman, Joshua T.; Wang, Po-Jen

    2018-01-01

    Dark matter may be a thermal relic whose abundance is set by mutual annihilations among multiple species. Traditionally, this coannihilation scenario has been applied to weak scale dark matter that is highly degenerate with other states. We show that coannihilation among states with split masses points to dark matter that is exponentially lighter than the weak scale, down to the keV scale. We highlight the regime where dark matter does not participate in the annihilations that dilute its numb...

  1. Asymmetric capture of Dirac dark matter by the Sun

    International Nuclear Information System (INIS)

    Blennow, Mattias; Clementz, Stefan

    2015-01-01

    Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles and anti-particles is possible even for an annihilation cross section in the range expected for thermal relic dark matter. Since the captured number of particles are competitive with asymmetric dark matter models in a large range of parameter space, one may expect solar physics to be altered by the capture of Dirac dark matter. It is thus possible that solutions to the solar composition problem may be searched for in these type of models

  2. Asymmetric capture of Dirac dark matter by the Sun

    Energy Technology Data Exchange (ETDEWEB)

    Blennow, Mattias; Clementz, Stefan [Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Albanova University Center,106 91, Stockholm (Sweden)

    2015-08-18

    Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles and anti-particles is possible even for an annihilation cross section in the range expected for thermal relic dark matter. Since the captured number of particles are competitive with asymmetric dark matter models in a large range of parameter space, one may expect solar physics to be altered by the capture of Dirac dark matter. It is thus possible that solutions to the solar composition problem may be searched for in these type of models.

  3. Asymmetric capture of Dirac dark matter by the Sun

    Energy Technology Data Exchange (ETDEWEB)

    Blennow, Mattias; Clementz, Stefan, E-mail: emb@kth.se, E-mail: scl@kth.se [Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Albanova University Center, 106 91, Stockholm (Sweden)

    2015-08-01

    Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles and anti-particles is possible even for an annihilation cross section in the range expected for thermal relic dark matter. Since the captured number of particles are competitive with asymmetric dark matter models in a large range of parameter space, one may expect solar physics to be altered by the capture of Dirac dark matter. It is thus possible that solutions to the solar composition problem may be searched for in these type of models.

  4. Dark energy and dark matter in galaxy halos

    International Nuclear Information System (INIS)

    Tetradis, N.

    2006-01-01

    We consider the possibility that the dark matter is coupled through its mass to a scalar field associated with the dark energy of the Universe. In order for such a field to play a role at the present cosmological distances, it must be effectively massless at galactic length scales. We discuss the effect of the field on the distribution of dark matter in galaxy halos. We show that the profile of the distribution outside the galaxy core remains largely unaffected and the approximately flat rotation curves persist. The dispersion of the dark matter velocity is enhanced by a potentially large factor relative to the case of zero coupling between dark energy and dark matter. The counting rates in terrestrial dark matter detectors are similarly enhanced. Existing bounds on the properties of dark matter candidates can be extended to the coupled case, by taking into account the enhancement factor

  5. The dark matter of galaxy voids

    Science.gov (United States)

    Sutter, P. M.; Lavaux, Guilhem; Wandelt, Benjamin D.; Weinberg, David H.; Warren, Michael S.

    2014-03-01

    How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing sparsely and densely sampled galaxy surveys to a high-resolution N-body simulation. We compare these galaxy voids to voids found in the halo distribution, low-resolution dark matter and high-resolution dark matter. We find that voids at all scales in densely sampled surveys - and medium- to large-scale voids in sparse surveys - trace the same underdensities as dark matter, but they are larger in radius by ˜20 per cent, they have somewhat shallower density profiles and they have centres offset by ˜ 0.4Rv rms. However, in void-to-void comparison we find that shape estimators are less robust to sampling, and the largest voids in sparsely sampled surveys suffer fragmentation at their edges. We find that voids in galaxy surveys always correspond to underdensities in the dark matter, though the centres may be offset. When this offset is taken into account, we recover almost identical radial density profiles between galaxies and dark matter. All mock catalogues used in this work are available at http://www.cosmicvoids.net.

  6. Primakoff Prize Talk: The Search for Dark Sectors

    Science.gov (United States)

    Essig, Rouven

    2015-04-01

    Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly interesting possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. Examples of dark sector particles include dark photons, axions, axion-like particles, and dark matter. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. This talk summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. Particular emphasis will be given to the search for dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model hypercharge, with masses in the MeV-to-GeV range. Experimental searches include low-energy e+e- colliders, new and old high-intensity fixed-target experiments, and high-energy colliders. The talk will highlight the APEX and HPS experiments at Jefferson Lab, which are pioneering, low-cost experiments to search for dark photons in fixed target electroproduction. Over the next few years, they have the potential for a transformative discovery.

  7. High-redshift quasars in the Cold Dark Matter cosmogony

    International Nuclear Information System (INIS)

    Efstathiou, G.; Rees, M.J.

    1988-01-01

    The relationship between high-redshift quasars and the epoch of galaxy formation in the Cold Dark Matter (CDM) cosmogony is investigated. Luminous quasars could only form after galactic sized systems had collapsed. A constant comoving density of luminous quasars between z = 2 and z = 4 is compatible with the CDM model if quasars are short-lived and radiate at about the Eddington limit. However, according to the CDM model the abundance of high-luminosity quasars must decline exponentially at higher redshifts. Even if all protogalaxies form quasars, and about 1 per cent of the baryons within a protogalaxy collapse into a compact object, a steep fall in the density of quasars with L > 10 47 erg s -1 at redshifts z ≥ 5. The existence of a 'cut-off' in the quasar numbers at high redshift could therefore supply an important test of the CDM theory. (author)

  8. Supersymmetric dark matter: Indirect detection

    International Nuclear Information System (INIS)

    Bergstroem, L.

    2000-01-01

    Dark matter detection experiments are improving to the point where they can detect or restrict the primary particle physics candidates for non baryonic dark matter. The methods for detection are usually categorized as direct, i.e., searching for signals caused by passage of dark matter particles in terrestrial detectors, or indirect. Indirect detection methods include searching for antimatter and gamma rays, in particular gamma ray lines, in cosmic rays and high-energy neutrinos from the centre of the Earth or Sun caused by accretion and annihilation of dark matter particles. A review is given of recent progress in indirect detection, both on the theoretical and experimental side

  9. Is Self-Interacting Dark Matter Undergoing Dark Fusion?

    Energy Technology Data Exchange (ETDEWEB)

    McDermott, Samuel D.

    2017-11-02

    We suggest that two-to-two dark matter fusion may be the relaxation process that resolves the small-scale structure problems of the cold collisionless dark matter paradigm. In order for the fusion cross section to scale correctly across many decades of astrophysical masses from dwarf galaxies to galaxy clusters, we require the fractional binding energy released to be greater than v^n ~ [10^{-(2-3)}]^n, where n=1,2 depends on local dark sector chemistry. The size of the dark-sector interaction cross sections must be sigma ~ 0.1-1 barn, moderately larger than for Standard Model deuteron fusion, indicating a dark nuclear scale Lambda ~ O(100 MeV). Dark fusion firmly predicts constant sigma v below the characteristic velocities of galaxy clusters. Observations of the inner structure of galaxy groups with velocity dispersion of several hundred kilometer per second, of which a handful have been identified, could differentiate dark fusion from a dark photon model.

  10. Constraint on dark matter annihilation with dark star formation using Fermi extragalactic diffuse gamma-ray background data

    International Nuclear Information System (INIS)

    Yuan, Qiang; Yue, Bin; Chen, Xuelei; Zhang, Bing

    2011-01-01

    It has been proposed that during the formation of the first generation stars there might be a ''dark star'' phase in which the power of the star comes from dark matter annihilation. The adiabatic contraction process to form the dark star would result in a highly concentrated density profile of the host halo at the same time, which may give enhanced indirect detection signals of dark matter. In this work we investigate the extragalactic γ-ray background from dark matter annihilation with such a dark star formation scenario, and employ the isotropic γ-ray data from Fermi-LAT to constrain the model parameters of dark matter. The results suffer from large uncertainties of both the formation rate of the first generation stars and the subsequent evolution effects of the host halos of the dark stars. We find, in the most optimistic case for γ-ray production via dark matter annihilation, the expected extragalactic γ-ray flux will be enhanced by 1-2 orders of magnitude. In such a case, the annihilation cross section of the supersymmetric dark matter can be constrained to the thermal production level, and the leptonic dark matter model which is proposed to explain the positron/electron excesses can be well excluded. Conversely, if the positron/electron excesses are of a dark matter annihilation origin, then the early Universe environment is such that no dark star can form

  11. Dark matter in and around stars

    International Nuclear Information System (INIS)

    Sivertsson, Sofia

    2009-01-01

    There is by now compelling evidence that most of the matter in the universe is in the form of dark matter, a form of matter quite different from the matter we experience in every day life. The gravitational effects of this dark matter have been observed in many different ways but its true nature is still unknown. In most models dark matter particles can annihilate with each other into standard model particles. The direct or indirect observation of such annihilation products could give important clues for the dark matter puzzle. For signals from dark matter annihilations to be detectable, typically high dark matter densities are required. Massive objects, such as stars, can increase the local dark matter density both via scattering off nucleons and by pulling in dark matter gravitationally as the star forms. Dark matter annihilations outside the star would give rise to gamma rays and this is discussed in the first paper. Furthermore dark matter annihilations inside the star would deposit energy inside the star which, if abundant enough, could alter the stellar evolution. Aspects of this are investigated in the second paper. Finally, local dark matter over densities formed in the early universe could still be around today; prospects of detecting gamma rays from such clumps are discussed in the third paper

  12. Global fits of the dark matter-nucleon effective interactions

    International Nuclear Information System (INIS)

    Catena, Riccardo; Gondolo, Paolo

    2014-01-01

    The effective theory of isoscalar dark matter-nucleon interactions mediated by heavy spin-one or spin-zero particles depends on 10 coupling constants besides the dark matter particle mass. Here we compare this 11-dimensional effective theory to current observations in a comprehensive statistical analysis of several direct detection experiments, including the recent LUX, SuperCDMS and CDMSlite results. From a multidimensional scan with about 3 million likelihood evaluations, we extract the marginalized posterior probability density functions (a Bayesian approach) and the profile likelihoods (a frequentist approach), as well as the associated credible regions and confidence levels, for each coupling constant vs dark matter mass and for each pair of coupling constants. We compare the Bayesian and frequentist approach in the light of the currently limited amount of data. We find that current direct detection data contain sufficient information to simultaneously constrain not only the familiar spin-independent and spin-dependent interactions, but also the remaining velocity and momentum dependent couplings predicted by the dark matter-nucleon effective theory. For current experiments associated with a null result, we find strong correlations between some pairs of coupling constants. For experiments that claim a signal (i.e., CoGeNT and DAMA), we find that pairs of coupling constants produce degenerate results

  13. Coupling q-Deformed Dark Energy to Dark Matter

    Directory of Open Access Journals (Sweden)

    Emre Dil

    2016-01-01

    Full Text Available We propose a novel coupled dark energy model which is assumed to occur as a q-deformed scalar field and investigate whether it will provide an expanding universe phase. We consider the q-deformed dark energy as coupled to dark matter inhomogeneities. We perform the phase-space analysis of the model by numerical methods and find the late-time accelerated attractor solutions. The attractor solutions imply that the coupled q-deformed dark energy model is consistent with the conventional dark energy models satisfying an acceleration phase of universe. At the end, we compare the cosmological parameters of deformed and standard dark energy models and interpret the implications.

  14. Dark matters

    International Nuclear Information System (INIS)

    Silk, Joseph

    2010-01-01

    One of the greatest mysteries in the cosmos is that it is mostly dark. That is, not only is the night sky dark, but also most of the matter and the energy in the universe is dark. For every atom visible in planets, stars and galaxies today there exists at least five or six times as much 'Dark Matter' in the universe. Astronomers and particle physicists today are seeking to unravel the nature of this mysterious but pervasive dark matter, which has profoundly influenced the formation of structure in the universe. Dark energy remains even more elusive, as we lack candidate fields that emerge from well established physics. I will describe various attempts to measure dark matter by direct and indirect means, and discuss the prospects for progress in unravelling dark energy.

  15. Invisible Higgs and Dark Matter

    DEFF Research Database (Denmark)

    Heikinheimo, Matti; Tuominen, Kimmo; Virkajärvi, Jussi Tuomas

    2012-01-01

    We investigate the possibility that a massive weakly interacting fermion simultaneously provides for a dominant component of the dark matter relic density and an invisible decay width of the Higgs boson at the LHC. As a concrete model realizing such dynamics we consider the minimal walking...... technicolor, although our results apply more generally. Taking into account the constraints from the electroweak precision measurements and current direct searches for dark matter particles, we find that such scenario is heavily constrained, and large portions of the parameter space are excluded....

  16. Direct dark matter searches—Test of the Big Bounce Cosmology

    International Nuclear Information System (INIS)

    Cheung, Yeuk-Kwan E.; Vergados, J.D.

    2015-01-01

    We consider the possibility of using dark matter particle's mass and its interaction cross section as a smoking gun signal of the existence of a Big Bounce at the early stage in the evolution of our currently observed universe. A study of dark matter production in the pre-bounce contraction and the post bounce expansion epochs of this universe reveals a new venue for achieving the observed relic abundance of our present universe. Specifically, it predicts a characteristic relation governing a dark matter mass and interaction cross section and a factor of 1/2 in thermally averaged cross section, as compared to the non-thermal production in standard cosmology, is needed for creating enough dark matter particle to satisfy the currently observed relic abundance because dark matter is being created during the pre-bounce contraction, in addition to the post-bounce expansion. As the production rate is lower than the Hubble expansion rate information of the bounce universe evolution is preserved. Therefore once the value of dark matter mass and interaction cross section are obtained by direct detection in laboratories, this alternative route becomes a signature prediction of the bounce universe scenario. This leads us to consider a scalar dark matter candidate, which if it is light, has important implications on dark matter searches

  17. Cosmological bounds on non-Abelian dark forces

    Science.gov (United States)

    Forestell, Lindsay; Morrissey, David E.; Sigurdson, Kris

    2018-04-01

    Non-Abelian dark gauge forces that do not couple directly to ordinary matter may be realized in nature. The minimal form of such a dark force is a pure Yang-Mills theory. If the dark sector is reheated in the early Universe, it will be realized as a set of dark gluons at high temperatures and as a collection of dark glueballs at lower temperatures, with a cosmological phase transition from one form to the other. Despite being dark, the gauge fields of the new force can connect indirectly to the standard model through nonrenormalizable operators. These operators will transfer energy between the dark and visible sectors, and they allow some or all of the dark glueballs to decay. In this work we investigate the cosmological evolution and decays of dark glueballs in the presence of connector operators to the standard model. Dark glueball decays can modify cosmological and astrophysical observables, and we use these considerations to put very strong limits on the existence of pure non-Abelian dark forces. On the other hand, if one or more of the dark glueballs are stable, we find that they can potentially make up the dark matter of the Universe.

  18. Cosmological models with Gurzadyan-Xue dark energy

    International Nuclear Information System (INIS)

    Vereshchagin, G V; Yegorian, G

    2006-01-01

    The formula for dark energy density derived by Gurzadyan and Xue is the only formula which provides (without a free parameter) a value for dark energy density in remarkable agreement with current cosmological datasets, unlike numerous phenomenological scenarios where the corresponding value is postulated. This formula suggests the possibility of variation of physical constants such as the speed of light and the gravitational constant. Considering several cosmological models based on that formula and deriving the cosmological equations for each case, we show that in all models source terms appear in the continuity equation. So, on one hand, GX models make up a rich set covering a lot of currently proposed models of dark energy; on the other hand, they reveal hidden symmetries, with a particular role of the separatrix Ω m = 2/3, and link with the issue of the content of physical constants

  19. Dark Energy in Practice

    CERN Document Server

    Sapone, Domenico

    2010-01-01

    In this paper we review a part of the approaches that have been considered to explain the extraordinary discovery of the late time acceleration of the Universe. We discuss the arguments that have led physicists and astronomers to accept dark energy as the current preferable candidate to explain the acceleration. We highlight the problems and the attempts to overcome the difficulties related to such a component. We also consider alternative theories capable of explaining the acceleration of the Universe, such as modification of gravity. We compare the two approaches and point out the observational consequences, reaching the sad but foresightful conclusion that we will not be able to distinguish between a Universe filled by dark energy or a Universe where gravity is different from General Relativity. We review the present observations and discuss the future experiments that will help us to learn more about our Universe. This is not intended to be a complete list of all the dark energy models but this paper shou...

  20. Sub-horizon evolution of cold dark matter perturbations through dark matter-dark energy equivalence epoch

    International Nuclear Information System (INIS)

    Piattella, O.F.; Martins, D.L.A.; Casarini, L.

    2014-01-01

    We consider a cosmological model of the late universe constituted by standard cold dark matter plus a dark energy component with constant equation of state w and constant effective speed of sound. By neglecting fluctuations in the dark energy component, we obtain an equation describing the evolution of sub-horizon cold dark matter perturbations through the epoch of dark matter-dark energy equality. We explore its analytic solutions and calculate an exact w-dependent correction for the dark matter growth function, logarithmic growth function and growth index parameter through the epoch considered. We test our analytic approximation with the numerical solution and find that the discrepancy is less than 1% for 0k = during the cosmic evolution up to a = 100

  1. EXTRAGALACTIC DARK MATTER AND DIRECT DETECTION EXPERIMENTS

    International Nuclear Information System (INIS)

    Baushev, A. N.

    2013-01-01

    Recent astronomical data strongly suggest that a significant part of the dark matter content of the Local Group and Virgo Supercluster is not incorporated into the galaxy halos and forms diffuse components of these galaxy clusters. A portion of the particles from these components may penetrate the Milky Way and make an extragalactic contribution to the total dark matter containment of our Galaxy. We find that the particles of the diffuse component of the Local Group are apt to contribute ∼12% to the total dark matter density near Earth. The particles of the extragalactic dark matter stand out because of their high speed (∼600 km s –1 ), i.e., they are much faster than the galactic dark matter. In addition, their speed distribution is very narrow (∼20 km s –1 ). The particles have an isotropic velocity distribution (perhaps, in contrast to the galactic dark matter). The extragalactic dark matter should provide a significant contribution to the direct detection signal. If the detector is sensitive only to the fast particles (v > 450 km s –1 ), then the signal may even dominate. The density of other possible types of the extragalactic dark matter (for instance, of the diffuse component of the Virgo Supercluster) should be relatively small and comparable with the average dark matter density of the universe. However, these particles can generate anomaly high-energy collisions in direct dark matter detectors.

  2. High-resolution simulations of galaxy formation in a cold dark matter scenario

    International Nuclear Information System (INIS)

    Kates, R.E.; Klypin, A.A.

    1990-01-01

    We present the results of our numerical simulations of galaxy clustering in a two-dimensional model. Our simulations allowed better resolution than could be obtained in three-dimensional simulations. We used a spectrum of initial perturbations corresponding to a cold dark matter (CDM) model and followed the history of each particle by modelling the shocking and subsequent cooling of matter. We took into account cooling processes in a hot plasma with primeval cosmic abundances of H and He as well as Compton cooling. (However, the influence of these processes on the trajectories of ordinary matter particles was not simulated in the present code.) As a result of the high resolution, we were able to observe a network of chains on all scales down to the limits of resolution. This network extends out from dense clusters and superclusters and penetrates into voids (with decreasing density). In addition to the dark matter network structure, a definite prediction of our simulations is the existence of a connected filamentary structure consisting of hot gas with a temperature of 10 6 K and extending over 100-150 Mpc. (Throughout this paper, we assume the Hubble constant H 0 =50 km/sec/Mpc.) These structures trace high-density filaments of the dark matter distribution and should be searched for in soft X-ray observations. In contrast to common assumptions, we found that peaks of the linearized density distribution were not reliable tracers of the eventual galaxy distribution. We were also able to demonstrate that the influence of small-scale fluctuations on the structure at larger scales is always small, even at the late nonlinear stage. (orig.)

  3. Unification of dark energy and dark matter

    International Nuclear Information System (INIS)

    Takahashi, Fuminobu; Yanagida, T.T.

    2006-01-01

    We propose a scenario in which dark energy and dark matter are described in a unified manner. The ultralight pseudo-Nambu-Goldstone (pNG) boson, A, naturally explains the observed magnitude of dark energy, while the bosonic supersymmetry partner of the pNG boson, B, can be a dominant component of dark matter. The decay of B into a pair of electron and positron may explain the 511 keV γ ray from the Galactic Center

  4. Tales from the dark side: Privacy dark strategies and privacy dark patterns

    DEFF Research Database (Denmark)

    Bösch, Christoph; Erb, Benjamin; Kargl, Frank

    2016-01-01

    Privacy strategies and privacy patterns are fundamental concepts of the privacy-by-design engineering approach. While they support a privacy-aware development process for IT systems, the concepts used by malicious, privacy-threatening parties are generally less understood and known. We argue...... that understanding the “dark side”, namely how personal data is abused, is of equal importance. In this paper, we introduce the concept of privacy dark strategies and privacy dark patterns and present a framework that collects, documents, and analyzes such malicious concepts. In addition, we investigate from...... a psychological perspective why privacy dark strategies are effective. The resulting framework allows for a better understanding of these dark concepts, fosters awareness, and supports the development of countermeasures. We aim to contribute to an easier detection and successive removal of such approaches from...

  5. Doppler effect on indirect detection of dark matter using dark matter only simulations

    Science.gov (United States)

    Powell, Devon; Laha, Ranjan; Ng, Kenny C. Y.; Abel, Tom

    2017-03-01

    Indirect detection of dark matter is a major avenue for discovery. However, baryonic backgrounds are diverse enough to mimic many possible signatures of dark matter. In this work, we study the newly proposed technique of dark matter velocity spectroscopy [E. G. Speckhard, K. C. Y. Ng, J. F. Beacom, and R. Laha, Phys. Rev. Lett. 116, 031301 (2016), 10.1103/PhysRevLett.116.031301]. The nonrotating dark matter halo and the Solar motion produce a distinct longitudinal dependence of the signal which is opposite in direction to that produced by baryons. Using collisionless dark matter only simulations of Milky Way like halos, we show that this new signature is robust and holds great promise. We develop mock observations by a high energy resolution x-ray spectrometer on a sounding rocket, the Micro-X experiment, to our test case, the 3.5 keV line. We show that by using six different pointings, Micro-X can exclude a constant line energy over various longitudes at ≥3 σ . The halo triaxiality is an important effect, and it will typically reduce the significance of this signal. We emphasize that this new smoking gun in motion signature of dark matter is general and is applicable to any dark matter candidate which produces a sharp photon feature in annihilation or decay.

  6. Constraints on the dark matter and dark energy interactions from weak lensing bispectrum tomography

    Energy Technology Data Exchange (ETDEWEB)

    An, Rui [School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Feng, Chang [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Wang, Bin, E-mail: an_rui@sjtu.edu.cn, E-mail: chang.feng@uci.edu, E-mail: wang_b@sjtu.edu.cn [Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, Yangzhou 225009 (China)

    2017-10-01

    We estimate uncertainties of cosmological parameters for phenomenological interacting dark energy models using weak lensing convergence power spectrum and bispectrum. We focus on the bispectrum tomography and examine how well the weak lensing bispectrum with tomography can constrain the interactions between dark sectors, as well as other cosmological parameters. Employing the Fisher matrix analysis, we forecast parameter uncertainties derived from weak lensing bispectra with a two-bin tomography and place upper bounds on strength of the interactions between the dark sectors. The cosmic shear will be measured from upcoming weak lensing surveys with high sensitivity, thus it enables us to use the higher order correlation functions of weak lensing to constrain the interaction between dark sectors and will potentially provide more stringent results with other observations combined.

  7. Dark Matter Decays from Nonminimal Coupling to Gravity.

    Science.gov (United States)

    Catà, Oscar; Ibarra, Alejandro; Ingenhütt, Sebastian

    2016-07-08

    We consider the standard model extended with a dark matter particle in curved spacetime, motivated by the fact that the only current evidence for dark matter is through its gravitational interactions, and we investigate the impact on the dark matter stability of terms in the Lagrangian linear in the dark matter field and proportional to the Ricci scalar. We show that this "gravity portal" induces decay even if the dark matter particle only has gravitational interactions, and that the decay branching ratios into standard model particles only depend on one free parameter: the dark matter mass. We study in detail the case of a singlet scalar as a dark matter candidate, which is assumed to be absolutely stable in flat spacetime due to a discrete Z_{2} symmetry, but which may decay in curved spacetimes due to a Z_{2}-breaking nonminimal coupling to gravity. We calculate the dark matter decay widths and we set conservative limits on the nonminimal coupling parameter from experiments. The limits are very stringent and suggest that there must exist an additional mechanism protecting the singlet scalar from decaying via this gravity portal.

  8. Excluding the light dark matter window of a 331 model using LHC and direct dark matter detection data

    Energy Technology Data Exchange (ETDEWEB)

    Cogollo, D. [Departamento de Física, Universidade Federal de Campina Grande, Caixa Postal 10071, 58109-970, Campina Grande, PB (Brazil); Gonzalez-Morales, Alma X.; Queiroz, Farinaldo S. [Department of Physics and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064 (United States); Teles, P. Rebello, E-mail: diegocogollo@df.ufcg.edu.br, E-mail: alxogonz@ucsc.edu, E-mail: fdasilva@ucsc.edu, E-mail: patricia.rebello.teles@cern.ch [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    2014-11-01

    We sift the impact of the recent Higgs precise measurements, and recent dark matter direct detection results, on the dark sector of an electroweak extension of the Standard Model that has a complex scalar as dark matter. We find that in this model the Higgs decays with a large branching ratio into dark matter particles, and charged scalars when these are kinematically available, for any coupling strength differently from the so called Higgs portal. Moreover, we compute the abundance and spin-independent WIMP-nucleon scattering cross section, which are driven by the Higgs and Z{sup '} boson processes. We decisively exclude the 1–500 GeV dark matter window and find the most stringent lower bound in the literature on the scale of symmetry breaking of the model namely 10 TeV, after applying the LUX-2013 limit. Interestingly, the projected XENON1T constraint will be able to rule out the entire 1 GeV–1000 GeV dark matter mass range. Lastly, for completeness, we compute the charged scalar production cross section at the LHC and comment on the possibility of detection at current and future LHC runnings.

  9. Excluding the light dark matter window of a 331 model using LHC and direct dark matter detection data

    International Nuclear Information System (INIS)

    Cogollo, D.; Gonzalez-Morales, Alma X.; Queiroz, Farinaldo S.; Teles, P. Rebello

    2014-01-01

    We sift the impact of the recent Higgs precise measurements, and recent dark matter direct detection results, on the dark sector of an electroweak extension of the Standard Model that has a complex scalar as dark matter. We find that in this model the Higgs decays with a large branching ratio into dark matter particles, and charged scalars when these are kinematically available, for any coupling strength differently from the so called Higgs portal. Moreover, we compute the abundance and spin-independent WIMP-nucleon scattering cross section, which are driven by the Higgs and Z ' boson processes. We decisively exclude the 1–500 GeV dark matter window and find the most stringent lower bound in the literature on the scale of symmetry breaking of the model namely 10 TeV, after applying the LUX-2013 limit. Interestingly, the projected XENON1T constraint will be able to rule out the entire 1 GeV–1000 GeV dark matter mass range. Lastly, for completeness, we compute the charged scalar production cross section at the LHC and comment on the possibility of detection at current and future LHC runnings

  10. Weak mixing below the weak scale in dark-matter direct detection

    Science.gov (United States)

    Brod, Joachim; Grinstein, Benjamin; Stamou, Emmanuel; Zupan, Jure

    2018-02-01

    If dark matter couples predominantly to the axial-vector currents with heavy quarks, the leading contribution to dark-matter scattering on nuclei is either due to one-loop weak corrections or due to the heavy-quark axial charges of the nucleons. We calculate the effects of Higgs and weak gauge-boson exchanges for dark matter coupling to heavy-quark axial-vector currents in an effective theory below the weak scale. By explicit computation, we show that the leading-logarithmic QCD corrections are important, and thus resum them to all orders using the renormalization group.

  11. Dark-ages reionization and galaxy formation simulation-XI. Clustering and halo masses of high redshift galaxies

    Science.gov (United States)

    Park, Jaehong; Kim, Han-Seek; Liu, Chuanwu; Trenti, Michele; Duffy, Alan R.; Geil, Paul M.; Mutch, Simon J.; Poole, Gregory B.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2017-12-01

    We investigate the clustering properties of Lyman-break galaxies (LBGs) at z ∼ 6 - 8. Using the semi-analytical model MERAXES constructed as part of the dark-ages reionization and galaxy-formation observables from numerical simulation (DRAGONS) project, we predict the angular correlation function (ACF) of LBGs at z ∼ 6 - 8. Overall, we find that the predicted ACFs are in good agreement with recent measurements at z ∼ 6 and z ∼ 7.2 from observations consisting of the Hubble eXtreme Deep Field, the Hubble Ultra Deep Field and cosmic sssembly near-infrared deep extragalactic legacy survey field. We confirm the dependence of clustering on luminosity, with more massive dark matter haloes hosting brighter galaxies, remains valid at high redshift. The predicted galaxy bias at fixed luminosity is found to increase with redshift, in agreement with observations. We find that LBGs of magnitude MAB(1600) < -19.4 at 6 ≲ z ≲ 8 reside in dark matter haloes of mean mass ∼1011.0-1011.5 M⊙, and this dark matter halo mass does not evolve significantly during reionisation.

  12. Lepton jets from radiating dark matter

    International Nuclear Information System (INIS)

    Buschmann, Malte; Kopp, Joachim; Liu, Jia; Machado, Pedro A.N.

    2015-01-01

    The idea that dark matter forms part of a larger dark sector is very intriguing, given the high degree of complexity of the visible sector. In this paper, we discuss lepton jets as a promising signature of an extended dark sector. As a simple toy model, we consider an O(GeV) DM fermion coupled to a new U(1) ′ gauge boson (dark photon) with a mass of order GeV and kinetically mixed with the Standard Model photon. Dark matter production at the LHC in this model is typically accompanied by collinear radiation of dark photons whose decay products can form lepton jets. We analyze the dynamics of collinear dark photon emission both analytically and numerically. In particular, we derive the dark photon energy spectrum using recursive analytic expressions, using Monte Carlo simulations in Pythia, and using an inverse Mellin transform to obtain the spectrum from its moments. In the second part of the paper, we simulate the expected lepton jet signatures from radiating dark matter at the LHC, carefully taking into account the various dark photon decay modes and allowing for both prompt and displaced decays. Using these simulations, we recast two existing ATLAS lepton jet searches to significantly restrict the parameter space of extended dark sector models, and we compute the expected sensitivity of future LHC searches.

  13. Revival of the unified dark energy-dark matter model?

    International Nuclear Information System (INIS)

    Bento, M.C.; Bertolami, O.; Sen, A.A.

    2004-01-01

    We consider the generalized Chaplygin gas (GCG) proposal for unification of dark energy and dark matter and show that it admits an unique decomposition into dark energy and dark matter components once phantomlike dark energy is excluded. Within this framework, we study structure formation and show that difficulties associated to unphysical oscillations or blowup in the matter power spectrum can be circumvented. Furthermore, we show that the dominance of dark energy is related to the time when energy density fluctuations start deviating from the linear δ∼a behavior

  14. High current ion sources

    International Nuclear Information System (INIS)

    Brown, I.G.

    1989-06-01

    The concept of high current ion source is both relative and evolutionary. Within the domain of one particular kind of ion source technology a current of microamperers might be 'high', while in another area a current of 10 Amperes could 'low'. Even within the domain of a single ion source type, what is considered high current performance today is routinely eclipsed by better performance and higher current output within a short period of time. Within their fields of application, there is a large number of kinds of ion sources that can justifiably be called high current. Thus, as a very limited example only, PIGs, Freemen sources, ECR sources, duoplasmatrons, field emission sources, and a great many more all have their high current variants. High current ion beams of gaseous and metallic species can be generated in a number of different ways. Ion sources of the kind developed at various laboratories around the world for the production of intense neutral beams for controlled fusion experiments are used to form large area proton deuteron beams of may tens of Amperes, and this technology can be used for other applications also. There has been significant progress in recent years in the use of microwave ion sources for high current ion beam generation, and this method is likely to find wide application in various different field application. Finally, high current beams of metal ions can be produced using metal vapor vacuum arc ion source technology. After a brief consideration of high current ion source design concepts, these three particular methods are reviewed in this paper

  15. Development of a high average current polarized electron source with long cathode operational lifetime

    Energy Technology Data Exchange (ETDEWEB)

    C. K. Sinclair; P. A. Adderley; B. M. Dunham; J. C. Hansknecht; P. Hartmann; M. Poelker; J. S. Price; P. M. Rutt; W. J. Schneider; M. Steigerwald

    2007-02-01

    Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory) require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2?105???C/cm2 and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  16. Dark Matter Profiles in Dwarf Galaxies: A Statistical Sample Using High-Resolution Hα Velocity Fields from PCWI

    Science.gov (United States)

    Relatores, Nicole C.; Newman, Andrew B.; Simon, Joshua D.; Ellis, Richard; Truong, Phuongmai N.; Blitz, Leo

    2018-01-01

    We present high quality Hα velocity fields for a sample of nearby dwarf galaxies (log M/M⊙ = 8.4-9.8) obtained as part of the Dark Matter in Dwarf Galaxies survey. The purpose of the survey is to investigate the cusp-core discrepancy by quantifying the variation of the inner slope of the dark matter distributions of 26 dwarf galaxies, which were selected as likely to have regular kinematics. The data were obtained with the Palomar Cosmic Web Imager, located on the Hale 5m telescope. We extract rotation curves from the velocity fields and use optical and infrared photometry to model the stellar mass distribution. We model the total mass distribution as the sum of a generalized Navarro-Frenk-White dark matter halo along with the stellar and gaseous components. We present the distribution of inner dark matter density profile slopes derived from this analysis. For a subset of galaxies, we compare our results to an independent analysis based on CO observations. In future work, we will compare the scatter in inner density slopes, as well as their correlations with galaxy properties, to theoretical predictions for dark matter core creation via supernovae feedback.

  17. Dissipative hidden sector dark matter

    Science.gov (United States)

    Foot, R.; Vagnozzi, S.

    2015-01-01

    A simple way of explaining dark matter without modifying known Standard Model physics is to require the existence of a hidden (dark) sector, which interacts with the visible one predominantly via gravity. We consider a hidden sector containing two stable particles charged under an unbroken U (1 )' gauge symmetry, hence featuring dissipative interactions. The massless gauge field associated with this symmetry, the dark photon, can interact via kinetic mixing with the ordinary photon. In fact, such an interaction of strength ε ˜10-9 appears to be necessary in order to explain galactic structure. We calculate the effect of this new physics on big bang nucleosynthesis and its contribution to the relativistic energy density at hydrogen recombination. We then examine the process of dark recombination, during which neutral dark states are formed, which is important for large-scale structure formation. Galactic structure is considered next, focusing on spiral and irregular galaxies. For these galaxies we modeled the dark matter halo (at the current epoch) as a dissipative plasma of dark matter particles, where the energy lost due to dissipation is compensated by the energy produced from ordinary supernovae (the core-collapse energy is transferred to the hidden sector via kinetic mixing induced processes in the supernova core). We find that such a dynamical halo model can reproduce several observed features of disk galaxies, including the cored density profile and the Tully-Fisher relation. We also discuss how elliptical and dwarf spheroidal galaxies could fit into this picture. Finally, these analyses are combined to set bounds on the parameter space of our model, which can serve as a guideline for future experimental searches.

  18. High Energy Cosmic Electrons: Messengers from Nearby Cosmic Ray Sources or Dark Matter?

    Science.gov (United States)

    Moiseev, Alexander

    2011-01-01

    This slide presentation reviews the recent discoveries by the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Telescope in reference to high energy cosmic electrons, and whether their source is cosmic rays or dark matter. Specific interest is devoted to Cosmic Ray electrons anisotropy,

  19. Influence of label information on dark chocolate acceptability.

    Science.gov (United States)

    Torres-Moreno, M; Tarrega, A; Torrescasana, E; Blanch, C

    2012-04-01

    The aim of the present work was to study how the information on product labels influences consumer expectations and their acceptance and purchase intention of dark chocolate. Six samples of dark chocolate, varying in brand (premium and store brand) and in type of product (regular dark chocolate, single cocoa origin dark chocolate and high percentage of cocoa dark chocolate), were evaluated by 109 consumers who scored their liking and purchase intention under three conditions: blind (only tasting the products), expected (observing product label information) and informed (tasting the products together with provision of the label information). In the expected condition, consumer liking was mainly affected by the brand. In the blind condition, differences in liking were due to the type of product; the samples with a high percentage of cocoa were those less preferred by consumers. Under the informed condition, liking of dark chocolates varied depending on both brand and type of product. Premium brand chocolates generated high consumer expectations of chocolate acceptability, which were fulfilled by the sensory characteristics of the products. Store brand chocolates created lower expectations, but when they were tasted they were as acceptable as premium chocolates. Claims of a high percentage of cocoa and single cocoa origin on labels did not generate higher expectations than regular dark chocolates. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Probing light nonthermal dark matter at the LHC

    Science.gov (United States)

    Dutta, Bhaskar; Gao, Yu; Kamon, Teruki

    2014-05-01

    This paper investigates the collider phenomenology of a minimal nonthermal dark matter model with a 1-GeV dark matter candidate, which naturally explains baryogenesis. Since the light dark matter is not parity protected, it can be singly produced at the LHC. This leads to large missing energy associated with an energetic jet whose transverse momentum distribution is featured by a Jacobian-like shape. The monojet, dijet, paired dijet, and two jets + missing energy channels are studied. Currently existing data at the Tevatron and LHC offer significant bounds on our model.

  1. Dark Matter: Looking for WIMPs in the Galactic Halo

    International Nuclear Information System (INIS)

    Akerib, Daniel S.

    2006-01-01

    Overwhelming observational evidence indicates that most of the matter in the Universe consists of non-baryonic dark matter. One possibility is that the dark matter is Weakly-Interacting Massive Particles (WIMPs) that were produced in the early Universe. These relics could comprise the Milky Way's dark halo and provide evidence for new particle physics, such as Supersymmetry. After reviewing some of the evidence for dark matter and the WIMP hypothesis, I will describe the strategy for searching for WIMPs, along with a survey of the current status and outlook. In particular, dark matter searches have begun to explore the region of parameter space where SUSY particles could provide dark matter candidates. I will also mention some of the recent theoretical work on dark matter candidates which is being done in anticipation of the turn-on of the LHC and as part of the active R and D on the ILC. Finally, a vigorous detector development program promises significant advances in WIMP sensitivity in the coming years

  2. CASTing light on dark matter particles

    CERN Multimedia

    2005-01-01

    CERN's CAST collaboration recently released first results from its search for solar axions, a candidate dark matter particle. Though they haven't found any axions yet, they have done much to narrow the hunt. The CAST experiment. Physicists think the universe is permeated with dark matter, particles that don't emit or absorb radiation and so are invisible to traditional telescopes. So far no one has found direct signs of dark matter. A different breed of telescope, however, may be able to see such particles. CERN's Axion Solar Telescope (CAST), currently the world's only working axion helioscope, is a superconducting test magnet from the Large Hadron Collider (LHC) that has been refurbished and outfitted with X-ray detectors, plus a focusing mirror system for X-rays that was recovered from the German space program. CAST stares into the sun in search of particles called axions, one of the leading candidates for dark matter. On 9 November, the CAST collaboration released the results of their first experimen...

  3. High Detectivity Graphene-Silicon Heterojunction Photodetector.

    Science.gov (United States)

    Li, Xinming; Zhu, Miao; Du, Mingde; Lv, Zheng; Zhang, Li; Li, Yuanchang; Yang, Yao; Yang, Tingting; Li, Xiao; Wang, Kunlin; Zhu, Hongwei; Fang, Ying

    2016-02-03

    A graphene/n-type silicon (n-Si) heterojunction has been demonstrated to exhibit strong rectifying behavior and high photoresponsivity, which can be utilized for the development of high-performance photodetectors. However, graphene/n-Si heterojunction photodetectors reported previously suffer from relatively low specific detectivity due to large dark current. Here, by introducing a thin interfacial oxide layer, the dark current of graphene/n-Si heterojunction has been reduced by two orders of magnitude at zero bias. At room temperature, the graphene/n-Si photodetector with interfacial oxide exhibits a specific detectivity up to 5.77 × 10(13) cm Hz(1/2) W(-1) at the peak wavelength of 890 nm in vacuum, which is highest reported detectivity at room temperature for planar graphene/Si heterojunction photodetectors. In addition, the improved graphene/n-Si heterojunction photodetectors possess high responsivity of 0.73 A W(-1) and high photo-to-dark current ratio of ≈10(7) . The current noise spectral density of the graphene/n-Si photodetector has been characterized under ambient and vacuum conditions, which shows that the dark current can be further suppressed in vacuum. These results demonstrate that graphene/Si heterojunction with interfacial oxide is promising for the development of high detectivity photodetectors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Dark Radiation predictions from general Large Volume Scenarios

    Science.gov (United States)

    Hebecker, Arthur; Mangat, Patrick; Rompineve, Fabrizio; Witkowski, Lukas T.

    2014-09-01

    Recent observations constrain the amount of Dark Radiation (Δ N eff ) and may even hint towards a non-zero value of Δ N eff . It is by now well-known that this puts stringent constraints on the sequestered Large Volume Scenario (LVS), i.e. on LVS realisations with the Standard Model at a singularity. We go beyond this setting by considering LVS models where SM fields are realised on 7-branes in the geometric regime. As we argue, this naturally goes together with high-scale supersymmetry. The abundance of Dark Radiation is determined by the competition between the decay of the lightest modulus to axions, to the SM Higgs and to gauge fields, and leads to strict constraints on these models. Nevertheless, these constructions can in principle meet current DR bounds due to decays into gauge bosons alone. Further, a rather robust prediction for a substantial amount of Dark Radiation can be made. This applies both to cases where the SM 4-cycles are stabilised by D-terms and are small `by accident', i.e. tuning, as well as to fibred models with the small cycles stabilised by loops. In these constructions the DR axion and the QCD axion are the same field and we require a tuning of the initial misalignment to avoid Dark Matter overproduction. Furthermore, we analyse a closely related setting where the SM lives at a singularity but couples to the volume modulus through flavour branes. We conclude that some of the most natural LVS settings with natural values of model parameters lead to Dark Radiation predictions just below the present observational limits. Barring a discovery, rather modest improvements of present Dark Radiation bounds can rule out many of these most simple and generic variants of the LVS.

  5. Gamma ray constraints on decaying dark matter

    DEFF Research Database (Denmark)

    Cirelli, M.; Moulin, E.; Panci, P.

    2012-01-01

    We derive new bounds on decaying dark matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range...... of dark matter masses and a variety of decay modes, excluding half-lives up to similar to 10(26) to few 10(27) seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e(+/-) spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices...

  6. Effect of CP violation in the singlet-doublet dark matter model

    Directory of Open Access Journals (Sweden)

    Tomohiro Abe

    2017-08-01

    Full Text Available We revisit the singlet-doublet dark matter model with a special emphasis on the effect of CP violation on the dark matter phenomenology. The CP violation in the dark sector induces a pseudoscalar interaction of a fermionic dark matter candidate with the SM Higgs boson. The pseudoscalar interaction helps the dark matter candidate evade the strong constraints from the dark matter direct detection experiments. We show that the model can explain the measured value of the dark matter density even if dark matter direct detection experiments do not observe any signal. We also show that the electron electric dipole moment is an important complement to the direct detection for testing this model. Its value is smaller than the current upper bound but within the reach of future experiments.

  7. Supplying Dark Energy from Scalar Field Dark Matter

    OpenAIRE

    Gogberashvili, Merab; Sakharov, Alexander S.

    2017-01-01

    We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.

  8. Dark stars

    DEFF Research Database (Denmark)

    Maselli, Andrea; Pnigouras, Pantelis; Nielsen, Niklas Grønlund

    2017-01-01

    to the formation of compact objects predominantly made of dark matter. Considering both fermionic and bosonic (scalar φ4) equations of state, we construct the equilibrium structure of rotating dark stars, focusing on their bulk properties and comparing them with baryonic neutron stars. We also show that these dark......Theoretical models of self-interacting dark matter represent a promising answer to a series of open problems within the so-called collisionless cold dark matter paradigm. In case of asymmetric dark matter, self-interactions might facilitate gravitational collapse and potentially lead...... objects admit the I-Love-Q universal relations, which link their moments of inertia, tidal deformabilities, and quadrupole moments. Finally, we prove that stars built with a dark matter equation of state are not compact enough to mimic black holes in general relativity, thus making them distinguishable...

  9. The traces of anisotropic dark energy in light of Planck

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, Wilmar; Kunz, Martin [Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 24 Quai Ernest Ansermet, 1211 Genève 4 (Switzerland); Hollenstein, Lukas, E-mail: wilmar.cardona@unige.ch, E-mail: lukas.hollenstein@zhaw.ch, E-mail: martin.kunz@unige.ch [IAS Institute of Applied Simulation, ZHAW Zurich University of Applied Sciences, Grüental, PO Box, 8820 Wädenswil (Switzerland)

    2014-07-01

    We study a dark energy model with non-zero anisotropic stress, either linked to the dark energy density or to the dark matter density. We compute approximate solutions that allow to characterise the behaviour of the dark energy model and to assess the stability of the perturbations. We also determine the current limits on such an anisotropic stress from the cosmic microwave background data by the Planck satellite, and derive the corresponding constraints on the modified growth parameters like the growth index, the effective Newton's constant and the gravitational slip.

  10. Gravitational effects of condensate dark matter on compact stellar objects

    International Nuclear Information System (INIS)

    Li, X.Y.; Wang, F.Y.; Cheng, K.S.

    2012-01-01

    We study the gravitational effect of non-self-annihilating dark matter on compact stellar objects. The self-interaction of condensate dark matter can give high accretion rate of dark matter onto stars. Phase transition to condensation state takes place when the dark matter density exceeds the critical value. A compact degenerate dark matter core is developed and alter the structure and stability of the stellar objects. Condensate dark matter admixed neutron stars is studied through the two-fluid TOV equation. The existence of condensate dark matter deforms the mass-radius relation of neutron stars and lower their maximum baryonic masses and radii. The possible effects on the Gamma-ray Burst rate in high redshift are discussed

  11. High current, high bandwidth laser diode current driver

    Science.gov (United States)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  12. Dark nebulae, dark lanes, and dust belts

    CERN Document Server

    Cooke, Antony

    2012-01-01

    As probably the only book of its type, this work is aimed at the observer who wants to spend time with something less conventional than the usual fare. Because we usually see objects in space by means of illumination of one kind or another, it has become routine to see them only in these terms. However, part of almost everything that we see is the defining dimension of dark shading, or even the complete obscuration of entire regions in space. Thus this book is focused on everything dark in space: those dark voids in the stellar fabric that mystified astronomers of old; the dark lanes reported in many star clusters; the magical dust belts or dusty regions that have given so many galaxies their identities; the great swirling 'folds' that we associate with bright nebulae; the small dark feature detectable even in some planetary nebulae; and more. Many observers pay scant attention to dark objects and details. Perhaps they are insufficiently aware of them or of the viewing potential they hold, but also it may be...

  13. Sourcing dark matter and dark energy from α-attractors

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Swagat S.; Sahni, Varun [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007 (India); Shtanov, Yuri, E-mail: swagat@iucaa.in, E-mail: varun@iucaa.in, E-mail: shtanov@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine)

    2017-06-01

    In [1], Kallosh and Linde drew attention to a new family of superconformal inflationary potentials, subsequently called α-attractors [2]. The α-attractor family can interpolate between a large class of inflationary models. It also has an important theoretical underpinning within the framework of supergravity. We demonstrate that the α-attractors have an even wider appeal since they may describe dark matter and perhaps even dark energy. The dark matter associated with the α-attractors, which we call α-dark matter (αDM), shares many of the attractive features of fuzzy dark matter, with V (φ) = ½ m {sup 2}φ{sup 2}, while having none of its drawbacks. Like fuzzy dark matter, αDM can have a large Jeans length which could resolve the cusp-core and substructure problems faced by standard cold dark matter. αDM also has an appealing tracker property which enables it to converge to the late-time dark matter asymptote, ( w ) ≅ 0, from a wide range of initial conditions. It thus avoids the enormous fine-tuning problems faced by the m {sup 2}φ{sup 2} potential in describing dark matter.

  14. Sourcing dark matter and dark energy from α-attractors

    International Nuclear Information System (INIS)

    Mishra, Swagat S.; Sahni, Varun; Shtanov, Yuri

    2017-01-01

    In [1], Kallosh and Linde drew attention to a new family of superconformal inflationary potentials, subsequently called α-attractors [2]. The α-attractor family can interpolate between a large class of inflationary models. It also has an important theoretical underpinning within the framework of supergravity. We demonstrate that the α-attractors have an even wider appeal since they may describe dark matter and perhaps even dark energy. The dark matter associated with the α-attractors, which we call α-dark matter (αDM), shares many of the attractive features of fuzzy dark matter, with V (φ) = ½ m 2 φ 2 , while having none of its drawbacks. Like fuzzy dark matter, αDM can have a large Jeans length which could resolve the cusp-core and substructure problems faced by standard cold dark matter. αDM also has an appealing tracker property which enables it to converge to the late-time dark matter asymptote, ( w ) ≅ 0, from a wide range of initial conditions. It thus avoids the enormous fine-tuning problems faced by the m 2 φ 2 potential in describing dark matter.

  15. Analytical Model for Voltage-Dependent Photo and Dark Currents in Bulk Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Mesbahus Saleheen

    2016-05-01

    Full Text Available A physics-based explicit mathematical model for the external voltage-dependent forward dark current in bulk heterojunction (BHJ organic solar cells is developed by considering Shockley-Read-Hall (SRH recombination and solving the continuity equations for both electrons and holes. An analytical model for the external voltage-dependent photocurrent in BHJ organic solar cells is also proposed by incorporating exponential photon absorption, dissociation efficiency of bound electron-hole pairs (EHPs, carrier trapping, and carrier drift and diffusion in the photon absorption layer. Modified Braun’s model is used to compute the electric field-dependent dissociation efficiency of the bound EHPs. The overall net current is calculated considering the actual solar spectrum. The mathematical models are verified by comparing the model calculations with various published experimental results. We analyze the effects of the contact properties, blend compositions, charge carrier transport properties (carrier mobility and lifetime, and cell design on the current-voltage characteristics. The power conversion efficiency of BHJ organic solar cells mostly depends on electron transport properties of the acceptor layer. The results of this paper indicate that improvement of charge carrier transport (both mobility and lifetime and dissociation of bound EHPs in organic blend are critically important to increase the power conversion efficiency of the BHJ solar cells.

  16. Gravitational wave from dark sector with dark pion

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, Koji [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Yamada, Masatoshi [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2017-07-01

    In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiral perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.

  17. Dark Matter

    Directory of Open Access Journals (Sweden)

    Einasto J.

    2011-06-01

    Full Text Available I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic web.

  18. Dark Energy vs. Dark Matter: Towards a Unifying Scalar Field?

    OpenAIRE

    Arbey, A.

    2008-01-01

    The standard model of cosmology suggests the existence of two components, "dark matter" and "dark energy", which determine the fate of the Universe. Their nature is still under investigation, and no direct proof of their existences has emerged yet. There exist alternative models which reinterpret the cosmological observations, for example by replacing the dark energy/dark matter hypothesis by the existence of a unique dark component, the dark fluid, which is able to mimic the behaviour of bot...

  19. In search of dark matter

    CERN Document Server

    Freeman, Kenneth C

    2006-01-01

    The dark matter problem is one of the most fundamental and profoundly difficult to solve problems in the history of science. Not knowing what makes up most of the known universe goes to the heart of our understanding of the Universe and our place in it. In Search of Dark Matter is the story of the emergence of the dark matter problem, from the initial erroneous ‘discovery’ of dark matter by Jan Oort to contemporary explanations for the nature of dark matter and its role in the origin and evolution of the Universe. Written for the educated non-scientist and scientist alike, it spans a variety of scientific disciplines, from observational astronomy to particle physics. Concepts that the reader will encounter along the way are at the cutting edge of scientific research. However the themes are explained in such a way that no prior understanding of science beyond a high school education is necessary.

  20. Conformal Gravity: Dark Matter and Dark Energy

    Directory of Open Access Journals (Sweden)

    Robert K. Nesbet

    2013-01-01

    Full Text Available This short review examines recent progress in understanding dark matter, dark energy, and galactic halos using theory that departs minimally from standard particle physics and cosmology. Strict conformal symmetry (local Weyl scaling covariance, postulated for all elementary massless fields, retains standard fermion and gauge boson theory but modifies Einstein–Hilbert general relativity and the Higgs scalar field model, with no new physical fields. Subgalactic phenomenology is retained. Without invoking dark matter, conformal gravity and a conformal Higgs model fit empirical data on galactic rotational velocities, galactic halos, and Hubble expansion including dark energy.

  1. Extracting hidden-photon dark matter from an LC-circuit

    International Nuclear Information System (INIS)

    Arias, Paola; Arza, Ariel; Gamboa, Jorge; Mendez, Fernando

    2014-11-01

    We point out that a cold dark matter condensate made of gauge bosons from an extra hidden U(1) sector - dubbed hidden-photons - can create a small, oscillating electric density current. Thus, they could also be searched for in the recently proposed LC-circuit setup conceived for axion cold dark matter search by Sikivie, Sullivan and Tanner. We estimate the sensitivity of this setup for hidden-photon cold dark matter and we find it could cover a sizable, so far unexplored parameter space.

  2. Extracting Hidden-Photon Dark Matter From an LC-Circuit

    CERN Document Server

    Arias, Paola; Döbrich, Babette; Gamboa, Jorge; Méndez, Fernando

    2015-01-01

    We point out that a cold dark matter condensate made of gauge bosons from an extra hidden U(1) sector - dubbed hidden- photons - can create a small, oscillating electric density current. Thus, they could also be searched for in the recently proposed LC-circuit setup conceived for axion cold dark matter search by Sikivie, Sullivan and Tanner. We estimate the sensitivity of this setup for hidden-photon cold dark matter and we find it could cover a sizable, so far unexplored parameter space.

  3. MISR Dark Water aerosol retrievals: operational algorithm sensitivity to particle non-sphericity

    Directory of Open Access Journals (Sweden)

    O. V. Kalashnikova

    2013-08-01

    Full Text Available The aim of this study is to theoretically investigate the sensitivity of the Multi-angle Imaging SpectroRadiometer (MISR operational (version 22 Dark Water retrieval algorithm to aerosol non-sphericity over the global oceans under actual observing conditions, accounting for current algorithm assumptions. Non-spherical (dust aerosol models, which were introduced in version 16 of the MISR aerosol product, improved the quality and coverage of retrievals in dusty regions. Due to the sensitivity of the retrieval to the presence of non-spherical aerosols, the MISR aerosol product has been successfully used to track the location and evolution of mineral dust plumes from the Sahara across the Atlantic, for example. However, the MISR global non-spherical aerosol optical depth (AOD fraction product has been found to have several climatological artifacts superimposed on valid detections of mineral dust, including high non-spherical fraction in the Southern Ocean and seasonally variable bands of high non-sphericity. In this paper we introduce a formal approach to examine the ability of the operational MISR Dark Water algorithm to distinguish among various spherical and non-spherical particles as a function of the variable MISR viewing geometry. We demonstrate the following under the criteria currently implemented: (1 Dark Water retrieval sensitivity to particle non-sphericity decreases for AOD below about 0.1 primarily due to an unnecessarily large lower bound imposed on the uncertainty in MISR observations at low light levels, and improves when this lower bound is removed; (2 Dark Water retrievals are able to distinguish between the spherical and non-spherical particles currently used for all MISR viewing geometries when the AOD exceeds 0.1; (3 the sensitivity of the MISR retrievals to aerosol non-sphericity varies in a complex way that depends on the sampling of the scattering phase function and the contribution from multiple scattering; and (4 non

  4. Multi-Messenger Astronomy and Dark Matter

    Science.gov (United States)

    Bergström, Lars

    This chapter presents the elaborated lecture notes on Multi-Messenger Astronomy and Dark Matter given by Lars Bergström at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". One of the main problems of astrophysics and astro-particle physics is that the nature of dark matter remains unsolved. There are basically three complementary approaches to try to solve this problem. One is the detection of new particles with accelerators, the second is the observation of various types of messengers from radio waves to gamma-ray photons and neutrinos, and the third is the use of ingenious experiments for direct detection of dark matter particles. After giving an introduction to the particle universe, the author discusses the relic density of particles, basic cross sections for neutrinos and gamma-rays, supersymmetric dark matter, detection methods for neutralino dark matter, particular dark matter candidates, the status of dark matter detection, a detailled calculation on an hypothetical "Saas-Fee Wimp", primordial black holes, and gravitational waves.

  5. Laboratory tests on dark energy

    International Nuclear Information System (INIS)

    Beck, Christian

    2006-01-01

    The physical nature of the currently observed dark energy in the universe is completely unclear, and many different theoretical models co-exist. Nevertheless, if dark energy is produced by vacuum fluctuations then there is a chance to probe some of its properties by simple laboratory tests based on Josephson junctions. These electronic devices can be used to perform 'vacuum fluctuation spectroscopy', by directly measuring a noise spectrum induced by vacuum fluctuations. One would expect to see a cutoff near 1.7 THz in the measured power spectrum, provided the new physics underlying dark energy couples to electric charge. The effect exploited by the Josephson junction is a subtile nonlinear mixing effect and has nothing to do with the Casimir effect or other effects based on van der Waals forces. A Josephson experiment of the suggested type will now be built, and we should know the result within the next 3 years

  6. Cardiovascular Benefits of Dark Chocolate?

    Science.gov (United States)

    Higginbotham, Erin; Taub, Pam R

    2015-12-01

    The use of cacao for health benefits dates back at least 3000 years. Our understanding of cacao has evolved with modern science. It is now felt based on extensive research the main health benefits of cacao stem from epicatechin, a flavanol found in cacao. The process of manufacturing dark chocolate retains epicatechin, whereas milk chocolate does not contain significant amounts of epicatechin. Thus, most of the current research studies are focused on dark chocolate. Both epidemiological and clinical studies suggest a beneficial effect of dark chocolate on blood pressure, lipids, and inflammation. Proposed mechanisms underlying these benefits include enhanced nitric oxide bioavailability and improved mitochondrial structure/function. Ultimately, further studies of this promising compound are needed to elucidate its potential for prevention and treatment of cardiovascular and metabolic diseases as well as other diseases that have underlying mechanisms of mitochondrial dysfunction and nitric oxide deficiency.

  7. Broadband and Resonant Approaches to Axion Dark Matter Detection.

    Science.gov (United States)

    Kahn, Yonatan; Safdi, Benjamin R; Thaler, Jesse

    2016-09-30

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10^{-14}-10^{-6}  eV. In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

  8. Effective dark energy equation of state in interacting dark energy models

    International Nuclear Information System (INIS)

    Avelino, P.P.; Silva, H.M.R. da

    2012-01-01

    In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

  9. Effective dark energy equation of state in interacting dark energy models

    Energy Technology Data Exchange (ETDEWEB)

    Avelino, P.P., E-mail: ppavelin@fc.up.pt [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Silva, H.M.R. da, E-mail: hilberto.silva@gmail.com [Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

    2012-07-24

    In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

  10. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  11. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  12. Light and heavy dark matter particles

    International Nuclear Information System (INIS)

    Boehm, C.; Fayet, P.; Silk, J.

    2004-01-01

    It has recently been pointed out that the 511 keV emission line detected by integral/SPI from the bulge of our galaxy could be explained by annihilations of light dark matter particles into e + e - . If such a signature is confirmed, then one might expect a conflict with the interpretation of very high energy gamma rays if they also turn out to be due to dark matter annihilations. Here, we propose a way to accommodate the existence of both signals being produced by dark matter annihilations through the existence of two stable (neutral) dark matter particles, as is possible in theories inspired from N=2 supersymmetry

  13. Dark energy from discrete spacetime.

    Directory of Open Access Journals (Sweden)

    Aaron D Trout

    Full Text Available Dark energy accounts for most of the matter-energy content of our universe, yet current theories of its origin rely on radical physical assumptions such as the holographic principle or controversial anthropic arguments. We give a better motivated explanation for dark energy, claiming that it arises from a small negative scalar-curvature present even in empty spacetime. The vacuum has this curvature because spacetime is fundamentally discrete and there are more ways for a discrete geometry to have negative curvature than positive. We explicitly compute this effect using a variant of the well known dynamical-triangulations (DT model for quantum gravity. Our model predicts a time-varying non-zero cosmological constant with a current value, [Formula: see text] in natural units, in agreement with observation. This calculation is made possible by a novel characterization of the possible DT action values combined with numerical evidence concerning their degeneracies.

  14. Dark energy from discrete spacetime.

    Science.gov (United States)

    Trout, Aaron D

    2013-01-01

    Dark energy accounts for most of the matter-energy content of our universe, yet current theories of its origin rely on radical physical assumptions such as the holographic principle or controversial anthropic arguments. We give a better motivated explanation for dark energy, claiming that it arises from a small negative scalar-curvature present even in empty spacetime. The vacuum has this curvature because spacetime is fundamentally discrete and there are more ways for a discrete geometry to have negative curvature than positive. We explicitly compute this effect using a variant of the well known dynamical-triangulations (DT) model for quantum gravity. Our model predicts a time-varying non-zero cosmological constant with a current value, [Formula: see text] in natural units, in agreement with observation. This calculation is made possible by a novel characterization of the possible DT action values combined with numerical evidence concerning their degeneracies.

  15. Unified Description of Dark Energy and Dark Matter

    OpenAIRE

    Petry, Walter

    2008-01-01

    Dark energy in the universe is assumed to be vacuum energy. The energy-momentum of vacuum is described by a scale-dependent cosmological constant. The equations of motion imply for the density of matter (dust) the sum of the usual matter density (luminous matter) and an additional matter density (dark matter) similar to the dark energy. The scale-dependent cosmological constant is given up to an exponent which is approximated by the experimentally decided density parameters of dark matter and...

  16. Dark energy and dark matter from primordial QGP

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, Vaishali, E-mail: vaidvavaishali24@gmail.com; Upadhyaya, G. K., E-mail: gopalujiain@yahoo.co.in [School of Studies in Physics, Vikram University Ujjain (India)

    2015-07-31

    Coloured relics servived after hadronization might have given birth to dark matter and dark energy. Theoretical ideas to solve mystery of cosmic acceleration, its origin and its status with reference to recent past are of much interest and are being proposed by many workers. In the present paper, we present a critical review of work done to understand the earliest appearance of dark matter and dark energy in the scenario of primordial quark gluon plasma (QGP) phase after Big Bang.

  17. Extracting hidden-photon dark matter from an LC-circuit

    International Nuclear Information System (INIS)

    Arias, Paola; Arza, Ariel; Gamboa, Jorge; Mendez, Fernando; Doebrich, Babette

    2015-01-01

    We point out that a cold dark matter condensate made of gauge bosons from an extra hidden U(1) sector - dubbed hidden photons - can create a small, oscillating electric density current. Thus, they could also be searched for in the recently proposed LC-circuit setup conceived for axion cold dark matter search by Sikivie, Sullivan and Tanner. We estimate the sensitivity of this setup for hidden-photon cold dark matter and we find it could cover a sizable, so far unexplored parameter space. (orig.)

  18. Elementary Goldstone Higgs Boson and Dark Matter

    DEFF Research Database (Denmark)

    Alanne, Tommi; Gertov, Helene; Sannino, Francesco

    2015-01-01

    We investigate a perturbative extension of the Standard Model featuring elementary pseudo-Goldstone Higgs and dark matter particles. These are two of the five Goldstone bosons parametrising the SU(4)/Sp(4) coset space. They acquire masses, and therefore become pseudo-Goldstone bosons, due...... of the theory, the quantum corrections are precisely calculable. The remaining pseudo-Goldstone boson is identified with the dark matter candidate because it is neutral with respect to the Standard Model and stable. By a direct comparison with the Large Hadron Collider experiments, the model is found...... to be phenomenologically viable. Furthermore the dark matter particle leads to the observed thermal relic density while respecting the most stringent current experimental constraints....

  19. Codecaying Dark Matter.

    Science.gov (United States)

    Dror, Jeff Asaf; Kuflik, Eric; Ng, Wee Hao

    2016-11-18

    We propose a new mechanism for thermal dark matter freeze-out, called codecaying dark matter. Multicomponent dark sectors with degenerate particles and out-of-equilibrium decays can codecay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes codecaying dark matter.

  20. Dark-Energy Equation-of-State parameter for high redshifts

    International Nuclear Information System (INIS)

    Montiel, Ariadna; Breton, Nora

    2011-01-01

    Since the elucidation of the nature of dark energy depends strongly on redshift observations, it is desirable to measure them over a wider range, but supernovae cannot be detected out past redshift 1.7. Gamma-ray-bursts (GRBs) offer means to extend the analysis to at least redshifts of > 6. The reason is that GRBs are visible across much larger distances than supernovae. GRBs are now known to have several light-curve and spectral properties from which the luminosity of the burst can be calculated, and it might GRBs become into standard candles. We have used data of 69 GRB to study the behavior of the parameter of the dark energy equation of state as a function of redshift.

  1. WIMP dark matter and supersymmetry searches with neutrino telescopes

    International Nuclear Information System (INIS)

    Fornengo, N.

    2011-01-01

    The particle physics interpretation of the missing-mass, or dark-matter, a problem of cosmological and astrophysical nature, is going to be placed under strong scrutiny in the next years. From the particle physics side, accelerator physics will deeply test theoretical ideas about new physics beyond the Standard Model, where a particle physics candidate to dark matter is often naturally obtained. From the astrophysical side, many probes are already providing a great deal of independent information on signals which can be produced by the galactic or extra-galactic dark matter. The current and new-generation experimental efforts are therefore going to place under deep scrutiny the theoretical explanations of the relevant signals. The ultimate hope is in fact to be able to disentangle a dark matter signal from the various sources of backgrounds. Neutrino telescopes are one of the prominent tools for looking at dark matter and search for a signal, the neutrino flux from Earth and Sun. In this neutrino dark matter searches share properties with both direct dark matter searches and cosmic-ray indirect dark matter searches, and therefore complement these different detection techniques.

  2. Embrace the Dark Side: Advancing the Dark Energy Survey

    Science.gov (United States)

    Suchyta, Eric

    The Dark Energy Survey (DES) is an ongoing cosmological survey intended to study the properties of the accelerated expansion of the Universe. In this dissertation, I present work of mine that has advanced the progress of DES. First is an introduction, which explores the physics of the cosmos, as well as how DES intends to probe it. Attention is given to developing the theoretical framework cosmologists use to describe the Universe, and to explaining observational evidence which has furnished our current conception of the cosmos. Emphasis is placed on the dark sector - dark matter and dark energy - the content of the Universe not explained by the Standard Model of particle physics. As its name suggests, the Dark Energy Survey has been specially designed to measure the properties of dark energy. DES will use a combination of galaxy cluster, weak gravitational lensing, angular clustering, and supernovae measurements to derive its state of the art constraints, each of which is discussed in the text. The work described in this dissertation includes science measurements directly related to the first three of these probes. The dissertation presents my contributions to the readout and control system of the Dark Energy Camera (DECam); the name of this software is SISPI. SISPI uses client-server and publish-subscribe communication patterns to coordinate and command actions among the many hardware components of DECam - the survey instrument for DES, a 570 megapixel CCD camera, mounted at prime focus of the Blanco 4-m Telescope. The SISPI work I discuss includes coding applications for DECam's filter changer mechanism and hexapod, as well as developing the Scripts Editor, a GUI application for DECam users to edit and export observing sequence SISPI can load and execute. Next, the dissertation describes the processing of early DES data, which I contributed. This furnished the data products used in the first-completed DES science analysis, and contributed to improving the

  3. Unified dark energy-dark matter model with inverse quintessence

    Energy Technology Data Exchange (ETDEWEB)

    Ansoldi, Stefano [ICRA — International Center for Relativistic Astrophysics, INFN — Istituto Nazionale di Fisica Nucleare, and Dipartimento di Matematica e Informatica, Università degli Studi di Udine, via delle Scienze 206, I-33100 Udine (UD) (Italy); Guendelman, Eduardo I., E-mail: ansoldi@fulbrightmail.org, E-mail: guendel@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negeev, Beer-Sheva 84105 (Israel)

    2013-05-01

    We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future.

  4. Unified dark energy-dark matter model with inverse quintessence

    International Nuclear Information System (INIS)

    Ansoldi, Stefano; Guendelman, Eduardo I.

    2013-01-01

    We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future

  5. Development of a high average current polarized electron source with long cathode operational lifetime

    Directory of Open Access Journals (Sweden)

    C. K. Sinclair

    2007-02-01

    Full Text Available Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2×10^{5}   C/cm^{2} and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  6. Is Self-Interacting Dark Matter Undergoing Dark Fusion?

    OpenAIRE

    McDermott, Samuel D.

    2018-01-01

    We suggest that two-to-two dark matter fusion may be the relaxation process that resolves the small-scale structure problems of the cold collisionless dark matter paradigm. In order for the fusion cross section to scale correctly across many decades of astrophysical masses from dwarf galaxies to galaxy clusters, we require the fractional binding energy released to be greater than vn∼(10−(2−3))n, where n=1, 2 depends on local dark sector chemistry. The size of the dark-sector interaction cross...

  7. Direct versus indirect detection of supersymmetric dark matter

    International Nuclear Information System (INIS)

    2003-01-01

    This document gathers the slides that were presented during the workshop 'direct versus indirect detection of supersymmetric dark matter'(about 30 contributions). This workshop intended to bring together people from the particle theory community, astrophysicists and cosmologists, as well as experimentalists involved in the detection of dark matter. The aim is to generate a discussion about current and future strategies for detection of SUSY dark matter (with focus, but not exclusively, on neutralinos). Complementarities between accelerator, direct and indirect searches as well as a comparison between the uncertainties in direct and indirect searches of dark matter, are supposed to be discussed. Among the issues which will be addressed are: -) the crucial questions related to the structure of galaxies (local dark matter density, clumping, anomalous velocity distributions, etc.) ; -) the possibilities offered by the present and future experimental facilities for direct and indirect (photon, neutrino) searches; -) the potential for the discovery of SUSY at LHC and beyond; and -) the parameterization of the SUSY breaking models beyond the minimal versions

  8. Indirect detection of dark matter with γ rays.

    Science.gov (United States)

    Funk, Stefan

    2015-10-06

    The details of what constitutes the majority of the mass that makes up dark matter in the Universe remains one of the prime puzzles of cosmology and particle physics today-80 y after the first observational indications. Today, it is widely accepted that dark matter exists and that it is very likely composed of elementary particles, which are weakly interacting and massive [weakly interacting massive particles (WIMPs)]. As important as dark matter is in our understanding of cosmology, the detection of these particles has thus far been elusive. Their primary properties such as mass and interaction cross sections are still unknown. Indirect detection searches for the products of WIMP annihilation or decay. This is generally done through observations of γ-ray photons or cosmic rays. Instruments such as the Fermi large-area telescope, high-energy stereoscopic system, major atmospheric gamma-ray imaging Cherenkov, and very energetic radiation imaging telescope array, combined with the future Cherenkov telescope array, will provide important complementarity to other search techniques. Given the expected sensitivities of all search techniques, we are at a stage where the WIMP scenario is facing stringent tests, and it can be expected that WIMPs will be either be detected or the scenario will be so severely constrained that it will have to be rethought. In this sense, we are on the threshold of discovery. In this article, I will give a general overview of the current status and future expectations for indirect searches of dark matter (WIMP) particles.

  9. Review of indirect detection of dark matter with neutrinos

    Science.gov (United States)

    Danninger, Matthias

    2017-09-01

    Dark Matter could be detected indirectly through the observation of neutrinos produced in dark matter self-annihilations or decays. Searches for such neutrino signals have resulted in stringent constraints on the dark matter self-annihilation cross section and the scattering cross section with matter. In recent years these searches have made significant progress in sensitivity through new search methodologies, new detection channels, and through the availability of rich datasets from neutrino telescopes and detectors, like IceCube, ANTARES, Super-Kamiokande, etc. We review recent experimental results and put them in context with respect to other direct and indirect dark matter searches. We also discuss prospects for discoveries at current and next generation neutrino detectors.

  10. Tools for model-independent bounds in direct dark matter searches

    DEFF Research Database (Denmark)

    Cirelli, M.; Del Nobile, E.; Panci, P.

    2013-01-01

    We discuss a framework (based on non-relativistic operators) and a self-contained set of numerical tools to derive the bounds from some current direct detection experiments on virtually any arbitrary model of Dark Matter elastically scattering on nuclei.......We discuss a framework (based on non-relativistic operators) and a self-contained set of numerical tools to derive the bounds from some current direct detection experiments on virtually any arbitrary model of Dark Matter elastically scattering on nuclei....

  11. Gravitational waves in cold dark matter

    Science.gov (United States)

    Flauger, Raphael; Weinberg, Steven

    2018-06-01

    We study the effects of cold dark matter on the propagation of gravitational waves of astrophysical and primordial origin. We show that the dominant effect of cold dark matter on gravitational waves from astrophysical sources is a small frequency dependent modification of the propagation speed of gravitational waves. However, the magnitude of the effect is too small to be detected in the near future. We furthermore show that the spectrum of primordial gravitational waves in principle contains detailed information about the properties of dark matter. However, depending on the wavelength, the effects are either suppressed because the dark matter is highly nonrelativistic or because it contributes a small fraction of the energy density of the universe. As a consequence, the effects of cold dark matter on primordial gravitational waves in practice also appear too small to be detectable.

  12. Dark Energy Camera for Blanco

    Energy Technology Data Exchange (ETDEWEB)

    Binder, Gary A.; /Caltech /SLAC

    2010-08-25

    In order to make accurate measurements of dark energy, a system is needed to monitor the focus and alignment of the Dark Energy Camera (DECam) to be located on the Blanco 4m Telescope for the upcoming Dark Energy Survey. One new approach under development is to fit out-of-focus star images to a point spread function from which information about the focus and tilt of the camera can be obtained. As a first test of a new algorithm using this idea, simulated star images produced from a model of DECam in the optics software Zemax were fitted. Then, real images from the Mosaic II imager currently installed on the Blanco telescope were used to investigate the algorithm's capabilities. A number of problems with the algorithm were found, and more work is needed to understand its limitations and improve its capabilities so it can reliably predict camera alignment and focus.

  13. Review of the Theoretical and Experimental Status of Dark Matter Identification with Cosmic-Ray Antideuterons

    Science.gov (United States)

    Aramaki, T.; Boggs, S.; Bufalino, S.; Dal, L.; von Doetinchem, P.; Donato, F.; Fornengo, N.; Fuke, H.; Grefe, M.; Hailey, C.; hide

    2016-01-01

    Recent years have seen increased theoretical and experimental effort towards the first-ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay. In contrast to indirect dark matter searches using positrons, antiprotons, or gamma-rays, which suffer from relatively high and uncertain astrophysical backgrounds, searches with antideuterons benefit from very suppressed conventional backgrounds, offering a potential breakthrough in unexplored phase space for dark matter. This article is based on the first dedicated cosmic-ray antideuteron workshop, which was held at UCLA in June 2014. It reviews broad classes of dark matter candidates that result in detectable cosmic-ray antideuteron fluxes, as well as the status and prospects of current experimental searches. The coalescence model of antideuteron production and the influence of antideuteron measurements at particle colliders are discussed. This is followed by a review of the modeling of antideuteron propagation through the magnetic fields, plasma currents, and molecular material of our Galaxy, the solar system, the Earth's geomagnetic field, and the atmosphere. Finally, the three ongoing or planned experiments that are sensitive to cosmic-ray antideuterons, BESS, AMS-02, and GAPS, are detailed. As cosmic-ray antideuteron detection is a rare event search, multiple experiments with orthogonal techniques and backgrounds are essential. Therefore, the combination of AMS-02 and GAPS antideuteron searches is highly desirable. Many theoretical and experimental groups have contributed to these studies over the last decade, this review aims to provide the first coherent discussion of the relevant dark matter theories that antideuterons probe, the challenges to predictions and interpretations of antideuteron signals, and the experimental efforts toward cosmic antideuteron detection.

  14. Superheavy thermal dark matter and primordial asymmetries

    International Nuclear Information System (INIS)

    Bramante, Joseph; Unwin, James

    2017-01-01

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10 10 GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

  15. Superheavy thermal dark matter and primordial asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Bramante, Joseph [Perimeter Institute for Theoretical Physics,31 Caroline St N, Waterloo, ON N2L 2Y5 (Canada); Unwin, James [Department of Physics, University of Illinois at Chicago,845 W Taylor St, Chicago, IL 60607 (United States)

    2017-02-23

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10{sup 10} GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

  16. TeV scale singlet dark matter

    International Nuclear Information System (INIS)

    Ponton, Eduardo; Randall, Lisa

    2009-01-01

    It is well known that stable weak scale particles are viable dark matter candidates since the annihilation cross section is naturally about the right magnitude to leave the correct thermal residual abundance. Many dark matter searches have focused on relatively light dark matter consistent with weak couplings to the Standard Model. However, in a strongly coupled theory, or even if the coupling is just a few times bigger than the Standard Model couplings, dark matter can have TeV-scale mass with the correct thermal relic abundance. Here we consider neutral TeV-mass scalar dark matter, its necessary interactions, and potential signals. We consider signals both with and without higher-dimension operators generated by strong coupling at the TeV scale, as might happen for example in an RS scenario. We find some potential for detection in high energy photons that depends on the dark matter distribution. Detection in positrons at lower energies, such as those PAMELA probes, would be difficult though a higher energy positron signal could in principle be detectable over background. However, a light dark matter particle with higher-dimensional interactions consistent with a TeV cutoff can in principle match PAMELA data.

  17. An Overview of Dark Matter Experiments at Jefferson Lab

    International Nuclear Information System (INIS)

    Boyce, James R

    2012-01-01

    Dark Matter research at Jefferson Lab started in 2006 with the LIght Pseudoscalar and Scalar Search (LIPSS) collaboration to check the validity of results reported by the PVLAS collaboration. In the intervening years interest in dark matter laboratory experiments has grown at Jefferson Lab. Current research underway or in planning stages probe various mass regions covering 14 orders of magnitude: from 10 −6 eV to 100 MeV. This presentation will be an overview of our dark matter searches, three of which focus on the hypothesized A' gauge boson.

  18. Interacting agegraphic dark energy

    International Nuclear Information System (INIS)

    Wei, Hao; Cai, Rong-Gen

    2009-01-01

    A new dark energy model, named ''agegraphic dark energy'', has been proposed recently, based on the so-called Karolyhazy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegraphic dark energy model and holographic dark energy model. The similarity and difference between agegraphic dark energy and holographic dark energy are also discussed. (orig.)

  19. Can modified gravity from extra dimensions explain dark matter effects?

    International Nuclear Information System (INIS)

    Kar, S.; Bharadwaj, S.; Pal, S.

    2006-01-01

    Observations on galaxy rotation curves and X-ray profiles of galaxy clusters over several decades have shown us that there exists a need for non-luminous (dark) matter. Cosmological observations also point towards the existence of dark components of two kinds - dark matter and dark energy - which, together, seem to be most of what is there the universe. However, for several years, there has been a line of thought which proposes modified gravity as an alternative to dark matter. In this article, we show, how the effective Einstein equations which arise in the context of the currently fashionable warped braneworld models, can explain the effects of dark matter as a manifestation of the consequences of the existence of extra dimensions. Finally, in order to distinguish between the effects of material dark matter and modified gravity, we calculate gravitational lensing in our modified gravity theory and show distinct differences in the deflection angles. If confirmed with observations, our results may shed new light on the existence of extra dimensions and dark matter. (authors)

  20. The interaction between dark energy and dark matter

    International Nuclear Information System (INIS)

    He Jianhua; Wang Bin

    2010-01-01

    In this review we first present a general formalism to study the growth of dark matter perturbations in the presence of interactions between dark matter(DM) and dark energy(DE). We also study the signature of such interaction on the temperature anisotropies of the large scale cosmic microwave background (CMB). We find that the effect of such interaction has significant signature on both the growth of dark matter structure and the late Integrated Sachs Wolfe effect(ISW). We further discuss the potential possibility to detect the coupling by cross-correlating CMB maps with tracers of the large scale structure. We finally confront this interacting model with WMAP 5-year data as well as other data sets. We find that in the 1σ range, the constrained coupling between dark sectors can solve the coincidence problem.

  1. Cryogenic high current discharges

    International Nuclear Information System (INIS)

    Meierovich, B.E.

    1994-01-01

    Z-pinches formed from frozen deuterium fibers by a rapidly rising current have enhanced stability and high neutron yield. The efforts to understand the enhanced stability and neutron yield on the basis of classical picture of Bennett equilibrium of the current channel has not given satisfactory results. The traditional approach does not take into account the essential difference between the frozen deuterium fiber Z-pinches and the usual Z-pinches such as exploding wires or classical gas-puffed Z-pinches. The very low temperature of the fiber atoms (10 K), together with the rapidly rising current, result in the coexistence of a high current channel with unionized fiber atoms for a substantial period of time. This phenomena lasts during the risetime. This approach takes into account the difference of the breakdown in a dielectric deuterium fiber and the breakdown in a metallic wire. This difference is essential to the understanding of specific features of cryogenic high current discharges. Z-pinches in frozen deuterium fibers should be considered as a qualitatively new phenomenon on the boundary of cryogenic and high current physics. It is a start of a new branch in plasma physics: the physics of cryogenic high current discharges

  2. Dark matter detectors

    International Nuclear Information System (INIS)

    Forster, G.

    1995-01-01

    A fundamental question of astrophysics and cosmology is the nature of dark matter. Astrophysical observations show clearly the existence of some kind of dark matter, though they cannot yet reveal its nature. Dark matter can consist of baryonic particles, or of other (known or unknown) elementary particles. Baryonic dark matter probably exists in the form of dust, gas, or small stars. Other elementary particles constituting the dark matter can possibly be measured in terrestrial experiments. Possibilities for dark matter particles are neutrinos, axions and weakly interacting massive particles (WIMPs). While a direct detection of relic neutrinos seems at the moment impossible, there are experiments looking for baryonic dark matter in the form of Massive Compact Halo Objects, and for particle dark matter in the form of axions and WIMPS. (orig.)

  3. Dark information of black hole radiation raised by dark energy

    Science.gov (United States)

    Ma, Yu-Han; Chen, Jin-Fu; Sun, Chang-Pu

    2018-06-01

    The "lost" information of black hole through the Hawking radiation was discovered being stored in the correlation among the non-thermally radiated particles (Parikh and Wilczek, 2000 [31], Zhang et al., 2009 [16]). This correlation information, which has not yet been proved locally observable in principle, is named by dark information. In this paper, we systematically study the influences of dark energy on black hole radiation, especially on the dark information. Calculating the radiation spectrum in the existence of dark energy by the approach of canonical typicality, which is reconfirmed by the quantum tunneling method, we find that the dark energy will effectively lower the Hawking temperature, and thus makes the black hole has longer life time. It is also discovered that the non-thermal effect of the black hole radiation is enhanced by dark energy so that the dark information of the radiation is increased. Our observation shows that, besides the mechanical effect (e.g., gravitational lensing effect), the dark energy rises the stored dark information, which could be probed by a non-local coincidence measurement similar to the coincidence counting of the Hanbury-Brown-Twiss experiment in quantum optics.

  4. Indirect search for neutralino dark matter with high energy neutrinos

    International Nuclear Information System (INIS)

    Barger, V.; Halzen, Francis; Hooper, Dan; Kao, Chung

    2002-01-01

    We investigate the prospects of indirect searches for supersymmetric neutralino dark matter. Relic neutralinos gravitationally accumulate in the Sun and their annihilations produce high energy neutrinos. Muon neutrinos of this origin can be seen in large detectors such as AMANDA, IceCube, and ANTARES. We evaluate the relic density and the detection rate in several models--the minimal supersymmetric model, minimal supergravity, and supergravity with nonuniversal Higgs boson masses at the grand unification scale. We make realistic estimates for the indirect detection rates including effects of the muon detection threshold, quark hadronization, and solar absorption. We find good prospects for detection of neutralinos with mass above 200 GeV

  5. High bicarbonate assimilation in the dark by Arctic bacteria.

    Science.gov (United States)

    Alonso-Sáez, Laura; Galand, Pierre E; Casamayor, Emilio O; Pedrós-Alió, Carlos; Bertilsson, Stefan

    2010-12-01

    Although both autotrophic and heterotrophic microorganisms incorporate CO₂ in the dark through different metabolic pathways, this process has usually been disregarded in oxic marine environments. We studied the significance and mediators of dark bicarbonate assimilation in dilution cultures inoculated with winter Arctic seawater. At stationary phase, bicarbonate incorporation rates were high (0.5-2.5 μg C L⁻¹ d⁻¹) and correlated with rates of bacterial heterotrophic production, suggesting that most of the incorporation was due to heterotrophs. Accordingly, very few typically chemoautotrophic bacteria were detected by 16S rRNA gene cloning. The genetic analysis of the biotin carboxylase gene accC putatively involved in archaeal CO₂ fixation did not yield any archaeal sequence, but amplified a variety of bacterial carboxylases involved in fatty acids biosynthesis, anaplerotic pathways and leucine catabolism. Gammaproteobacteria dominated the seawater cultures (40-70% of cell counts), followed by Betaproteobacteria and Flavobacteria as shown by catalyzed reporter deposition fluorescence in situ hybridization (CARDFISH). Both Beta- and Gammaproteobacteria were active in leucine and bicarbonate uptake, while Flavobacteria did not take up bicarbonate, as measured by microautoradiography combined with CARDFISH. Within Gammaproteobacteria, Pseudoalteromonas-Colwellia and Oleispira were very active in bicarbonate uptake (ca. 30 and 70% of active cells, respectively), while the group Arctic96B-16 did not take up bicarbonate. Our results suggest that, potentially, the incorporation of CO₂ can be relevant for the metabolism of specific Arctic heterotrophic phylotypes, promoting the maintenance of their cell activity and/or longer survival under resource depleted conditions.

  6. Enhanced energy conversion efficiency from high strength synthetic organic wastewater by sequential dark fermentative hydrogen production and algal lipid accumulation.

    Science.gov (United States)

    Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Xing, Defeng; Ren, Nan-Qi

    2014-04-01

    A two-stage process of sequential dark fermentative hydrogen production and microalgal cultivation was applied to enhance the energy conversion efficiency from high strength synthetic organic wastewater. Ethanol fermentation bacterium Ethanoligenens harbinense B49 was used as hydrogen producer, and the energy conversion efficiency and chemical oxygen demand (COD) removal efficiency reached 18.6% and 28.3% in dark fermentation. Acetate was the main soluble product in dark fermentative effluent, which was further utilized by microalga Scenedesmus sp. R-16. The final algal biomass concentration reached 1.98gL(-1), and the algal biomass was rich in lipid (40.9%) and low in protein (23.3%) and carbohydrate (11.9%). Compared with single dark fermentation stage, the energy conversion efficiency and COD removal efficiency of two-stage system remarkably increased 101% and 131%, respectively. This research provides a new approach for efficient energy production and wastewater treatment using a two-stage process combining dark fermentation and algal cultivation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Determining the dark matter mass with DeepCore

    Energy Technology Data Exchange (ETDEWEB)

    Das, Chitta R. [Centro de Física Teórica de Partículas, Instituto Superior Técnico (CFTP), Universidade Tćnica de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Mena, Olga [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, Apartado de Correos 22085, E-46071 Valencia (Spain); Palomares-Ruiz, Sergio, E-mail: sergio.palomares.ruiz@ist.utl.pt [Centro de Física Teórica de Partículas, Instituto Superior Técnico (CFTP), Universidade Tćnica de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, Apartado de Correos 22085, E-46071 Valencia (Spain); Pascoli, Silvia [IPPP, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

    2013-10-01

    Cosmological and astrophysical observations provide increasing evidence of the existence of dark matter in our Universe. Dark matter particles with a mass above a few GeV can be captured by the Sun, accumulate in the core, annihilate, and produce high energy neutrinos either directly or by subsequent decays of Standard Model particles. We investigate the prospects for indirect dark matter detection in the IceCube/DeepCore neutrino telescope and its capabilities to determine the dark matter mass.

  8. Light dark matter in NMSSM and implication on Higgs phenomenology

    International Nuclear Information System (INIS)

    Cao Junjie; Hikasa, Ken-ichi; Wang Wenyu; Yang Jinmin

    2011-01-01

    For the experimental search of neutralino dark matter, it is important to know its allowed mass and scattering cross section with the nucleon. In order to figure out how light a neutralino dark matter can be predicted in low energy supersymmetry, we scan over the parameter space of the NMSSM (next-to-minimal supersymmetric model), assuming all the relevant soft mass parameters to be below TeV scale. We find that in the parameter space allowed by current experiments the neutralino dark matter can be as light as a few GeV and its scattering rate off the nucleon can reach the sensitivity of XENON100 and CoGeNT. As a result, a sizable parameter space is excluded by the current XENON100 and CoGeNT data (the plausible CoGeNT dark matter signal can also be explained). The future 6000 kg-days exposure of XENON100 will further explore (but cannot completely cover) the remained parameter space. Moreover, we find that in such a light dark matter scenario a light CP-even or CP-odd Higgs boson must be present to satisfy the measured dark matter relic density. Consequently, the SM-like Higgs boson h SM may decay predominantly into a pair of light Higgs bosons or a pair of neutralinos so that the conventional decays like h SM →γγ is much suppressed.

  9. Dark energy and extended dark matter halos

    Science.gov (United States)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  10. Dark forces in the sky: signals from Z{sup ′} and the dark Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Nicole F.; Cai, Yi; Leane, Rebecca K. [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics,The University of Melbourne,Victoria 3010 (Australia)

    2016-08-01

    We consider the indirect detection signals for a self-consistent hidden U(1) model containing a Majorana dark matter candidate, χ, a dark gauge boson, Z{sup ′}, and a dark Higgs, s. Compared with a model containing only a dark matter candidate and Z{sup ′} mediator, the addition of the scalar provides a mass generation mechanism for the dark sector particles and is required in order to avoid unitarity violation at high energies. We find that the inclusion of the two mediators opens up a new two-body s-wave annihilation channel, χχ→sZ{sup ′}. This new process, which is missed in the usual single-mediator simplified model approach, can be the dominant annihilation channel. This provides rich phenomenology for indirect detection searches, allows indirect searches to explore regions of parameter space not accessible with other commonly considered s-wave annihilation processes, and enables both the Z{sup ′} and scalar couplings to be probed. We examine the phenomenology of the sector with a focus on this new process, and determine the limits on the model parameter space from Fermi data on dwarf spheriodal galaxies and other relevant experiments.

  11. Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

    KAUST Repository

    Mesa, Elena

    2017-04-21

    Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring and summer. Here we demonstrate that plankton community respiration evaluated under the continuous daylight conditions present in situ, tends to be higher than that evaluated in the dark. The ratio between community respiration measured in the light (Rlight) and in the dark (Rdark) increased as the 2/3 power of Rlight so that the Rlight:Rdark ratio increased from an average value of 1.37 at the median Rlight measured here (3.62 µmol O2 L-1 d-1) to an average value of 17.56 at the highest Rlight measured here (15.8 µmol O2 L-1 d-1). The role of respiratory processes as a source of CO2 in the Arctic has, therefore, been underestimated and is far more important than previously believed, particularly in the late spring, with 24 h photoperiods, when community respiration rates are highest.

  12. Electroweak baryogenesis, large Yukawas and dark matter

    International Nuclear Information System (INIS)

    Provenza, Alessio; Quiros, Mariano; Ullio, Piero

    2005-01-01

    It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show here that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upcoming experiments. We find, contrary to the standard lore, that indirect detection searches are more promising than direct ones, and they already exclude part of the parameter space

  13. Boosted dark matter signals uplifted with self-interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Kyoungchul, E-mail: kckong@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Mohlabeng, Gopolang, E-mail: mohlabeng319@gmail.com [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Park, Jong-Chul, E-mail: log1079@gmail.com [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-04-09

    We explore detection prospects of a non-standard dark sector in the context of boosted dark matter. We focus on a scenario with two dark matter particles of a large mass difference, where the heavier candidate is secluded and interacts with the standard model particles only at loops, escaping existing direct and indirect detection bounds. Yet its pair annihilation in the galactic center or in the Sun may produce boosted stable particles, which could be detected as visible Cherenkov light in large volume neutrino detectors. In such models with multiple candidates, self-interaction of dark matter particles is naturally utilized in the assisted freeze-out mechanism and is corroborated by various cosmological studies such as N-body simulations of structure formation, observations of dwarf galaxies, and the small scale problem. We show that self-interaction of the secluded (heavier) dark matter greatly enhances the capture rate in the Sun and results in promising signals at current and future experiments. We perform a detailed analysis of the boosted dark matter events for Super-Kamiokande, Hyper-Kamiokande and PINGU, including notable effects such as evaporation due to self-interaction and energy loss in the Sun.

  14. Asymmetric Dark Matter and Dark Radiation

    International Nuclear Information System (INIS)

    Blennow, Mattias; Martinez, Enrique Fernandez; Mena, Olga; Redondo, Javier; Serra, Paolo

    2012-01-01

    Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum

  15. The DarkLight Experiment: A Precision Search for New Physics at Low Energies

    OpenAIRE

    Balewski, J.; Bernauer, J.; Bessuille, J.; Corliss, R.; Cowan, R.; Epstein, C.; Fisher, P.; Hasell, D.; Ihloff, E.; Kahn, Y.; Kelsey, J.; Milner, R.; Steadman, S.; Thaler, J.; Tschalaer, C.

    2014-01-01

    We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac incident on a windowless gas target of molecular hydrogen. The complete final state including scatte...

  16. Correlation between dark matter and dark radiation in string compactifications

    International Nuclear Information System (INIS)

    Allahverdi, Rouzbeh; Cicoli, Michele; Dutta, Bhaskar; Sinha, Kuver

    2014-01-01

    Reheating in string compactifications is generically driven by the decay of the lightest modulus which produces Standard Model particles, dark matter and light hidden sector degrees of freedom that behave as dark radiation. This common origin allows us to find an interesting correlation between dark matter and dark radiation. By combining present upper bounds on the effective number of neutrino species N eff with lower bounds on the reheating temperature as a function of the dark matter mass m DM from Fermi data, we obtain strong constraints on the (N eff , m DM )-plane. Most of the allowed region in this plane corresponds to non-thermal scenarios with Higgsino-like dark matter. Thermal dark matter can be allowed only if N eff tends to its Standard Model value. We show that the above situation is realised in models with perturbative moduli stabilisation where the production of dark radiation is unavoidable since bulk closed string axions remain light and do not get eaten up by anomalous U(1)s

  17. High-voltage high-current triggering vacuum switch

    International Nuclear Information System (INIS)

    Alferov, D.F.; Bunin, R.A.; Evsin, D.V.; Sidorov, V.A.

    2012-01-01

    Experimental investigations of switching and breaking capacities of the new high current triggered vacuum switch (TVS) are carried out at various parameters of discharge current. It has been shown that the high current triggered vacuum switch TVS can switch repeatedly a current from units up to ten kiloampers with duration up to ten millisecond [ru

  18. The Galactic Halo in Mixed Dark Matter Cosmologies

    NARCIS (Netherlands)

    Anderhalden, D.; Diemand, J.; Bertone, G.; Macciò, A.V.; Schneider, A.

    2012-01-01

    A possible solution to the small scale problems of the cold dark matter (CDM) scenario is that the dark matter consists of two components, a cold and a warm one. We perform a set of high resolution simulations of the Milky Way halo varying the mass of the WDM particle (mWDM) and the cosmic dark

  19. LEP shines light on dark matter

    International Nuclear Information System (INIS)

    Fox, Patrick J.; Harnik, Roni; Kopp, Joachim; Tsai, Yuhsin

    2011-01-01

    Dark matter pair production at high energy colliders may leave observable signatures in the energy and momentum spectra of the objects recoiling against the dark matter. We use LEP data on monophoton events with large missing energy to constrain the coupling of dark matter to electrons. Within a large class of models, our limits are complementary to and competitive with limits on dark matter annihilation and on WIMP-nucleon scattering from indirect and direct searches. Our limits, however, do not suffer from systematic and astrophysical uncertainties associated with direct and indirect limits. For example, we are able to rule out light (< or approx. 10 GeV) thermal relic dark matter with universal couplings exclusively to charged leptons. In addition, for dark matter mass below about 80 GeV, LEP limits are stronger than Fermi constraints on annihilation into charged leptons in dwarf spheroidal galaxies. Within its kinematic reach, LEP also provides the strongest constraints on the spin-dependent direct detection cross section in models with universal couplings to both quarks and leptons. In such models the strongest limit is also set on spin-independent scattering for dark matter masses below ∼4 GeV. Throughout our discussion, we consider both low energy effective theories of dark matter, as well as several motivated renormalizable scenarios involving light mediators.

  20. High dark inorganic carbon fixation rates by specific microbial groups in the Atlantic off the Galician coast (NW Iberian margin).

    Science.gov (United States)

    Guerrero-Feijóo, Elisa; Sintes, Eva; Herndl, Gerhard J; Varela, Marta M

    2018-02-01

    Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production throughout the water column, however, more prominently in the bathypelagic waters. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) allowed us to identify several microbial groups involved in dark DIC uptake. The contribution of SAR406 (Marinimicrobia), SAR324 (Deltaproteobacteria) and Alteromonas (Gammaproteobacteria) to the dark DIC fixation was significantly higher than that of SAR202 (Chloroflexi) and Thaumarchaeota, in agreement with their contribution to microbial abundance. Q-PCR on the gene encoding for the ammonia monooxygenase subunit A (amoA) from the putatively high versus low ammonia concentration ecotypes revealed their depth-stratified distribution pattern. Taken together, our results indicate that chemoautotrophy is widespread among microbes in the dark ocean, particularly in bathypelagic waters. This chemolithoautotrophic biomass production in the dark ocean, depleted in bio-available organic matter, might play a substantial role in sustaining the dark ocean's food web. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. High-energy Neutrino Flares from X-Ray Bright and Dark Tidal Disruption Events

    Energy Technology Data Exchange (ETDEWEB)

    Senno, Nicholas; Murase, Kohta; Mészáros, Peter [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2017-03-20

    X-ray and γ-ray observations by the Swift satellite revealed that a fraction of tidal disruption events (TDEs) have relativistic jets. Jetted TDEs have been considered to be potential sources of very-high-energy cosmic-rays and neutrinos. In this work, using semi-analytical methods, we calculate neutrino spectra of X-ray bright TDEs with powerful jets and dark TDEs with possible choked jets, respectively. We estimate their neutrino fluxes and find that non-detection would give us an upper limit on the baryon loading of the jet luminosity contained in cosmic-rays ξ {sub cr} ≲ 20–50 for Sw J1644+57. We show that X-ray bright TDEs make a sub-dominant (≲5%–10%) contribution to IceCube’s diffuse neutrino flux, and study possible contributions of X-ray dark TDEs given that particles are accelerated in choked jets or disk winds. We discuss future prospects for multi-messenger searches of the brightest TDEs.

  2. Measurement technology of RF interference current in high current system

    Science.gov (United States)

    Zhao, Zhihua; Li, Jianxuan; Zhang, Xiangming; Zhang, Lei

    2018-06-01

    Current probe is a detection method commonly used in electromagnetic compatibility. With the development of power electronics technology, the power level of power conversion devices is constantly increasing, and the power current of the electric energy conversion device in the electromagnetic launch system can reach 10kA. Current probe conventionally used in EMC (electromagnetic compatibility) detection cannot meet the test requirements on high current system due to the magnetic saturation problem. The conventional high current sensor is also not suitable for the RF (Radio Frequency) interference current measurement in high current power device due to the high noise level in the output of active amplifier. In this paper, a passive flexible current probe based on Rogowski coil and matching resistance is proposed that can withstand high current and has low noise level, to solve the measurement problems of interference current in high current power converter. And both differential mode and common mode current detection can be easily carried out with the proposed probe because of the probe's flexible structure.

  3. Searches for dark photons at the Mainz Microtron

    Energy Technology Data Exchange (ETDEWEB)

    Merkel, H.; Achenbach, P.; Gayoso, C. Ayerbe; Beranek, T.; Bernauer, J. C.; Böhm, R.; Correa, L.; Denig, A.; Distler, M. O.; Esser, A.; Gómez, M.; Kegel, S.; Kohl, Y.; Mihovilovič, M.; Middleton, D. G.; Müller, U.; Nungesser, L.; Pochodzalla, J.; Rohrbeck, M.; Majos, S. Sánchez [Institut für Kernphysik, Johannes Gutenberg-Universität, D-55099 Mainz (Germany); and others

    2013-11-07

    The A1 Collaboration at the Mainz Microtron (MAMI) operates high resolution spectrometers at very high luminosities for fixed target electron scattering experiments. The setup is well suited for the search for dark photons in the mass range between 50 MeV and 300 MeV. In these experiments, a possible dark photon would appear as a sharp peak in the mass spectrum of di-lepton electro-production. In this presentation the potential of the setup is presented and the possibilities for future experiments for dark photon searches at MAMI are discussed.

  4. Dark energy two decades after: observables, probes, consistency tests.

    Science.gov (United States)

    Huterer, Dragan; Shafer, Daniel L

    2018-01-01

    The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark energy, the new component that causes the acceleration, has since become extremely strong, owing to an impressive variety of increasingly precise measurements of the expansion history and the growth of structure in the universe. Still, one of the central challenges of modern cosmology is to shed light on the physical mechanism behind the accelerating universe. In this review, we briefly summarize the developments that led to the discovery of dark energy. Next, we discuss the parametric descriptions of dark energy and the cosmological tests that allow us to better understand its nature. We then review the cosmological probes of dark energy. For each probe, we briefly discuss the physics behind it and its prospects for measuring dark energy properties. We end with a summary of the current status of dark energy research.

  5. with dark matter

    Indian Academy of Sciences (India)

    2012-11-16

    Nov 16, 2012 ... November 2012 physics pp. 1271–1274. Radiative see-saw formula in ... on neutrino physics, dark matter and all fermion masses and mixings. ... as such, high-energy accelerators cannot directly test the underlying origin of ...

  6. Adiabatic instability in coupled dark energy/dark matter models

    International Nuclear Information System (INIS)

    Bean, Rachel; Flanagan, Eanna E.; Trodden, Mark

    2008-01-01

    We consider theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the Universe. Such theories can possess an adiabatic regime in which the quintessence field always sits at the minimum of its effective potential, which is set by the local dark matter density. We show that if the coupling strength is much larger than gravitational, then the adiabatic regime is always subject to an instability. The instability, which can also be thought of as a type of Jeans instability, is characterized by a negative sound speed squared of an effective coupled dark matter/dark energy fluid, and results in the exponential growth of small scale modes. We discuss the role of the instability in specific coupled cold dark matter and mass varying neutrino models of dark energy and clarify for these theories the regimes in which the instability can be evaded due to nonadiabaticity or weak coupling.

  7. Dark Matter

    International Nuclear Information System (INIS)

    Bashir, A.; Cotti, U.; De Leon, C. L.; Raya, A; Villasenor, L.

    2008-01-01

    One of the biggest scientific mysteries of our time resides in the identification of the particles that constitute a large fraction of the mass of our Universe, generically known as dark matter. We review the observations and the experimental data that imply the existence of dark matter. We briefly discuss the properties of the two best dark-matter candidate particles and the experimental techniques presently used to try to discover them. Finally, we mention a proposed project that has recently emerged within the Mexican community to look for dark matter

  8. S-Channel Dark Matter Simplified Models and Unitarity

    CERN Document Server

    Englert, Christoph; Spannowsky, Michael

    The ultraviolet structure of $s$-channel mediator dark matter simplified models at hadron colliders is considered. In terms of commonly studied $s$-channel mediator simplified models it is argued that at arbitrarily high energies the perturbative description of dark matter production in high energy scattering at hadron colliders will break down in a number of cases. This is analogous to the well documented breakdown of an EFT description of dark matter collider production. With this in mind, to diagnose whether or not the use of simplified models at the LHC is valid, perturbative unitarity of the scattering amplitude in the processes relevant to LHC dark matter searches is studied. The results are as one would expect: at the LHC and future proton colliders the simplified model descriptions of dark matter production are in general valid. As a result of the general discussion, a simple new class of previously unconsidered `Fermiophobic Scalar' simplified models is proposed, in which a scalar mediator couples to...

  9. Direct versus indirect detection of supersymmetric dark matter

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This document gathers the slides that were presented during the workshop 'direct versus indirect detection of supersymmetric dark matter'(about 30 contributions). This workshop intended to bring together people from the particle theory community, astrophysicists and cosmologists, as well as experimentalists involved in the detection of dark matter. The aim is to generate a discussion about current and future strategies for detection of SUSY dark matter (with focus, but not exclusively, on neutralinos). Complementarities between accelerator, direct and indirect searches as well as a comparison between the uncertainties in direct and indirect searches of dark matter, are supposed to be discussed. Among the issues which will be addressed are: -) the crucial questions related to the structure of galaxies (local dark matter density, clumping, anomalous velocity distributions, etc.) ; -) the possibilities offered by the present and future experimental facilities for direct and indirect (photon, neutrino) searches; -) the potential for the discovery of SUSY at LHC and beyond; and -) the parameterization of the SUSY breaking models beyond the minimal versions.

  10. Dirac dark matter and b →s ℓ+ℓ- with U(1) gauge symmetry

    Science.gov (United States)

    Celis, Alejandro; Feng, Wan-Zhe; Vollmann, Martin

    2017-02-01

    We revisit the possibility of a Dirac fermion dark matter candidate in the light of current b →s ℓ+ℓ- anomalies by investigating a minimal extension of the Standard Model with a horizontal U(1 ) ' local symmetry. Dark matter stability is protected by a remnant Z2 symmetry arising after spontaneous symmetry breaking of U(1 ) '. The associated Z' gauge boson can accommodate current hints of new physics in b →s ℓ+ℓ- decays, and acts as a vector portal between dark matter and the visible sector. We find that the model is severely constrained by a combination of precision measurements at flavor factories, LHC searches for dilepton resonances, as well as direct and indirect dark matter searches. Despite this, viable regions of the parameter space accommodating the observed dark matter relic abundance and the b →s ℓ+ℓ-anomalies still persist for dark matter and Z ' masses in the TeV range.

  11. Sequential dark-photo fermentation and autotrophic microalgal growth for high-yield and CO{sub 2}-free biohydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Yung-Chung [Department of Chemical Engineering, National Cheng Kung University, Tainan 701 (China); Chen, Chun-Yen [Department of Chemical Engineering, National Cheng Kung University, Tainan 701 (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan (China); Lee, Chi-Mei [Department of Environmental Engineering, National Chung Hsing University, Taichung (China); Chang, Jo-Shu [Department of Chemical Engineering, National Cheng Kung University, Tainan 701 (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan (China); Center for Biosciences and Biotechnology, National Cheng Kung University, Tainan (China)

    2010-10-15

    Dark fermentation, photo fermentation, and autotrophic microalgae cultivation were integrated to establish a high-yield and CO{sub 2}-free biohydrogen production system by using different feedstock. Among the four carbon sources examined, sucrose was the most effective for the sequential dark (with Clostridium butyricum CGS5) and photo (with Rhodopseudomonas palutris WP3-5) fermentation process. The sequential dark-photo fermentation was stably operated for nearly 80 days, giving a maximum H{sub 2} yield of 11.61 mol H{sub 2}/mol sucrose and a H{sub 2} production rate of 673.93 ml/h/l. The biogas produced from the sequential dark-photo fermentation (containing ca. 40.0% CO{sub 2}) was directly fed into a microalga culture (Chlorella vulgaris C-C) cultivated at 30 C under 60 {mu}mol/m{sup 2}/s illumination. The CO{sub 2} produced from the fermentation processes was completely consumed during the autotrophic growth of C. vulgaris C-C, resulting in a microalgal biomass concentration of 1999 mg/l composed mainly of 48.0% protein, 23.0% carbohydrate and 12.3% lipid. (author)

  12. Metastable dark energy

    Directory of Open Access Journals (Sweden)

    Ricardo G. Landim

    2017-01-01

    Full Text Available We build a model of metastable dark energy, in which the observed vacuum energy is the value of the scalar potential at the false vacuum. The scalar potential is given by a sum of even self-interactions up to order six. The deviation from the Minkowski vacuum is due to a term suppressed by the Planck scale. The decay time of the metastable vacuum can easily accommodate a mean life time compatible with the age of the universe. The metastable dark energy is also embedded into a model with SU(2R symmetry. The dark energy doublet and the dark matter doublet naturally interact with each other. A three-body decay of the dark energy particle into (cold and warm dark matter can be as long as large fraction of the age of the universe, if the mediator is massive enough, the lower bound being at intermediate energy level some orders below the grand unification scale. Such a decay shows a different form of interaction between dark matter and dark energy, and the model opens a new window to investigate the dark sector from the point-of-view of particle physics.

  13. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    International Nuclear Information System (INIS)

    Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

    2014-01-01

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

  14. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    Science.gov (United States)

    Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

    2014-06-01

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

  15. Accretion of dark matter by stars.

    Science.gov (United States)

    Brito, Richard; Cardoso, Vitor; Okawa, Hirotada

    2015-09-11

    Searches for dark matter imprints are one of the most active areas of current research. We focus here on light fields with mass m_{B}, such as axions and axionlike candidates. Using perturbative techniques and full-blown nonlinear numerical relativity methods, we show the following. (i) Dark matter can pile up in the center of stars, leading to configurations and geometries oscillating with a frequency that is a multiple of f=2.5×10^{14}(m_{B}c^{2}/eV)  Hz. These configurations are stable throughout most of the parameter space, and arise out of credible mechanisms for dark-matter capture. Stars with bosonic cores may also develop in other theories with effective mass couplings, such as (massless) scalar-tensor theories. We also show that (ii) collapse of the host star to a black hole is avoided by efficient gravitational cooling mechanisms.

  16. Small but mighty: Dark matter substructures

    Science.gov (United States)

    Cyr-Racine, Francis-Yan; Keeton, Charles; Moustakas, Leonidas

    2018-01-01

    The fundamental properties of dark matter, such as its mass, self-interaction, and coupling to other particles, can have a major impact on the evolution of cosmological density fluctuations on small length scales. Strong gravitational lenses have long been recognized as powerful tools to study the dark matter distribution on these small subgalactic scales. In this talk, we discuss how gravitationally lensed quasars and extended lensed arcs could be used to probe non minimal dark matter models. We comment on the possibilities enabled by precise astrometry, deep imaging, and time delays to extract information about mass substructures inside lens galaxies. To this end, we introduce a new lensing statistics that allows for a robust diagnostic of the presence of perturbations caused by substructures. We determine which properties of mass substructures are most readily constrained by lensing data and forecast the constraining power of current and future observations.

  17. Proton and gamma -Rays Irradiation-Induced Dark Current Random Telegraph Signal in a 0.18-mu{{m}} CMOS Image Sensor

    Science.gov (United States)

    Martin, E.; Nuns, T.; Virmontois, C.; David, J.-P.; Gilard, O.

    2013-08-01

    The dark current random telegraph signal (RTS) behavior has been studied in a five-transistor-per-pixel (5T) pinned photodiode 0.18-μm COTS active pixel sensor (APS). Several devices, irradiated using protons and gamma rays, have been studied in order to assess the ionizing and displacement damage effects. The influence of the proton energy, fluence, ionizing dose and applied bias during irradiation on the number of RTS pixels, the number of discrete levels, maximum transition amplitude, and mean switching time constants is investigated.

  18. Partially acoustic dark matter, interacting dark radiation, and large scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Chacko, Zackaria [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Cui, Yanou [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Department of Physics and Astronomy, University of California-Riverside,University Ave, Riverside, CA 92521 (United States); Perimeter Institute, 31 Caroline Street, North Waterloo, Ontario N2L 2Y5 (Canada); Hong, Sungwoo [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Okui, Takemichi [Department of Physics, Florida State University,College Avenue, Tallahassee, FL 32306 (United States); Tsai, Yuhsinz [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States)

    2016-12-21

    The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H{sub 0} and the matter density perturbation σ{sub 8} inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ{sub 8} problem, while the presence of tightly coupled dark radiation ameliorates the H{sub 0} problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

  19. Partially acoustic dark matter, interacting dark radiation, and large scale structure

    International Nuclear Information System (INIS)

    Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi; Tsai, Yuhsinz

    2016-01-01

    The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

  20. Inflation, Dark Matter, and Dark Energy in the String Landscape

    OpenAIRE

    Liddle, Andrew R; Ureña-López, L Arturo

    2006-01-01

    We consider the conditions needed to unify the description of dark matter, dark energy and inflation in the context of the string landscape. We find that incomplete decay of the inflaton field gives the possibility that a single field is responsible for all three phenomena. By contrast, unifying dark matter and dark energy into a single field, separate from the inflaton, appears rather difficult.

  1. High-voltage, high-current, solid-state closing switch

    Science.gov (United States)

    Focia, Ronald Jeffrey

    2017-08-22

    A high-voltage, high-current, solid-state closing switch uses a field-effect transistor (e.g., a MOSFET) to trigger a high-voltage stack of thyristors. The switch can have a high hold-off voltage, high current carrying capacity, and high time-rate-of-change of current, di/dt. The fast closing switch can be used in pulsed power applications.

  2. Fluctuations and dark count rates in superconducting NbN single-photon detectors

    International Nuclear Information System (INIS)

    Engel, Andreas; Semenov, Alexei; Huebers, Heinz-Wilhelm; Il'in, Kostya; Siegel, Michael

    2005-01-01

    We measured the temperature- and current-dependence of dark count rates of a superconducting singlephoton detector. The detector's key element is a 84 nm wide meander strip line fabricated from a 5 nm thick NbN film. Due to its reduced dimensions various types of fluctuations can cause temporal and localized transitions into a resistive state leading to dark count events. Adopting a recent refinement of the hotspot model we achieve a satisfying description of the experimental dark count rates taking into account fluctuations of the Cooper-pair density and current-assisted unbinding of vortex-antivortex pairs. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. [Correlation of fine structures of distributions of amplitudes of a photomultiplier dark current fluctuations with the Earth rotations about its axis].

    Science.gov (United States)

    Fedorov, M V; Belousov, L V; Voeĭkov, V L; Zenchenko, K I; Zenchenko, T A; Konradov, A A; Shnol', S E

    2001-01-01

    The fine structures of distributions of photomultiplier dark current fluctuations measured in two laboratories 2000 km distant from other: in the international Institute of Biophysics (Neuss, Germany) and in the Moscow State University (Moscow, Russia) were compared. It is shown that similar forms of appropriate histograms are apparently more often realized at both locations at the same local time. This confirms the previous conclusion that the fine structure of distributions correlates with rotation of the Earth about its axis.

  4. Dark Sky Protection and Education - Izera Dark Sky Park

    Science.gov (United States)

    Berlicki, Arkadiusz; Kolomanski, Sylwester; Mrozek, Tomasz; Zakowicz, Grzegorz

    2015-08-01

    Darkness of the night sky is a natural component of our environment and should be protected against negative effects of human activities. The night darkness is necessary for balanced life of plants, animals and people. Unfortunately, development of human civilization and technology has led to the substantial increase of the night-sky brightness and to situation where nights are no more dark in many areas of the World. This phenomenon is called "light pollution" and it can be rank among such problems as chemical pollution of air, water and soil. Besides the environment, the light pollution can also affect e.g. the scientific activities of astronomers - many observatories built in the past began to be located within the glow of city lights making the night observations difficult, or even impossible.In order to protect the natural darkness of nights many so-called "dark sky parks" were established, where the darkness is preserved, similar to typical nature reserves. The role of these parks is not only conservation but also education, supporting to make society aware of how serious the problem of the light pollution is.History of the dark sky areas in Europe began on November 4, 2009 in Jizerka - a small village situated in the Izera Mountains, when Izera Dark Sky Park (IDSP) was established - it was the first transboundary dark sky park in the World. The idea of establishing that dark sky park in the Izera Mountains originated from a need to give to the society in Poland and Czech Republic the knowledge about the light pollution. Izera Dark Sky Park is a part of the astro-tourism project "Astro Izery" that combines tourist attraction of Izera Valley and astronomical education under the wonderful starry Izera sky. Besides the IDSP, the project Astro Izery consists of the set of simple astronomical instruments (gnomon, sundial), natural educational trail "Solar System Model", and astronomical events for the public. In addition, twice a year we organize a 3-4 days

  5. The phase-space structure of a dark-matter halo: Implications for dark-matter direct detection experiments

    International Nuclear Information System (INIS)

    Helmi, Amina; White, Simon D.M.; Springel, Volker

    2002-01-01

    We study the phase-space structure of a dark-matter halo formed in a high resolution simulation of a ΛCDM cosmology. Our goal is to quantify how much substructure is left over from the inhomogeneous growth of the halo, and how it may affect the signal in experiments aimed at detecting the dark matter particles directly. If we focus on the equivalent of 'solar vicinity', we find that the dark matter is smoothly distributed in space. The probability of detecting particles bound within dense lumps of individual mass less than 10 7 M · h -1 is small, less than 10 -2 . The velocity ellipsoid in the solar neighborhood deviates only slightly from a multivariate Gaussian, and can be thought of as a superposition of thousands of kinematically cold streams. The motions of the most energetic particles are, however, strongly clumped and highly anisotropic. We conclude that experiments may safely assume a smooth multivariate Gaussian distribution to represent the kinematics of dark-matter particles in the solar neighborhood. Experiments sensitive to the direction of motion of the incident particles could exploit the expected anisotropy to learn about the recent merging history of our Galaxy

  6. Cosmological acceleration. Dark energy or modified gravity?

    International Nuclear Information System (INIS)

    Bludman, S.

    2006-05-01

    We review the evidence for recently accelerating cosmological expansion or ''dark energy'', either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any constituent Dark Energy. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of ''dark energy'' cannot be derived from the homogeneous expansion history alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, but also allow nearly static Dark Energy or gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish between static and ''dynamic'' ''dark energy''. But, cosmologically distinguishing the Concordance Model ΛCDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati low-curvature modifications of Einstein gravity may also be detected in refined observations in the solar system (Lue and Starkman) or at the intermediate Vainstein scale (Iorio) in isolated galaxy clusters. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence (''Why so small now?'') without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity. (Orig.)

  7. Cosmological acceleration. Dark energy or modified gravity?

    Energy Technology Data Exchange (ETDEWEB)

    Bludman, S

    2006-05-15

    We review the evidence for recently accelerating cosmological expansion or ''dark energy'', either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any constituent Dark Energy. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of ''dark energy'' cannot be derived from the homogeneous expansion history alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, but also allow nearly static Dark Energy or gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish between static and ''dynamic'' ''dark energy''. But, cosmologically distinguishing the Concordance Model {lambda}CDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati low-curvature modifications of Einstein gravity may also be detected in refined observations in the solar system (Lue and Starkman) or at the intermediate Vainstein scale (Iorio) in isolated galaxy clusters. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence (''Why so small now?'') without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity. (Orig.)

  8. THE DARK DISK OF THE MILKY WAY

    International Nuclear Information System (INIS)

    Purcell, Chris W.; Bullock, James S.; Kaplinghat, Manoj

    2009-01-01

    Massive satellite accretions onto early galactic disks can lead to the deposition of dark matter in disk-like configurations that co-rotate with the galaxy. This phenomenon has potentially dramatic consequences for dark matter detection experiments. We utilize focused, high-resolution simulations of accretion events onto disks designed to be Galaxy analogues, and compare the resultant disks to the morphological and kinematic properties of the Milky Way's thick disk in order to bracket the range of co-rotating accreted dark matter. In agreement with previous results, we find that the Milky Way's merger history must have been unusually quiescent compared to median Λ cold dark matter expectations and, therefore, its dark disk must be relatively small: the fraction of accreted dark disk material near the Sun is about 20% of the host halo density or smaller and the co-rotating dark matter fraction near the Sun, defined as particles moving with a rotational velocity lag less than 50 km s -1 , is enhanced by about 30% or less compared to a standard halo model. Such a dark disk could contribute dominantly to the low energy (of order keV for a dark matter particle with mass 100 GeV) nuclear recoil event rate of direct detection experiments, but it will not change the likelihood of detection significantly. These dark disks provide testable predictions of weakly interacting massive particle dark matter models and should be considered in detailed comparisons to experimental data. Our findings suggest that the dark disk of the Milky Way may provide a detectable signal for indirect detection experiments, contributing up to about 25% of the dark matter self-annihilation signal in the direction of the center of the Galaxy, lending the signal a noticeably oblate morphology.

  9. arXiv Supplying Dark Energy from Scalar Field Dark Matter

    CERN Document Server

    Gogberashvili, Merab

    We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.

  10. White noise from dark matter: 21 cm observations of early baryon collapse

    International Nuclear Information System (INIS)

    Zurek, Kathryn M.; Hogan, Craig J.

    2007-01-01

    In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift z∼20. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below k∼10h Mpc -1 (the smallest scales currently measured with the Lyman-α forest). Exotic dark matter dynamics, such as would arise from scalar dark matter with a late phase transition (similar to an axion, but with lower mass), or primordial black hole dark matter, create such an amplification of small scale power. The dark matter produced in such a phase transition collapses into minihalos, with a size given by the dark matter mass within the horizon at the phase transition. If the mass of the initial minihalos is larger than ∼10 -3 M · , the modified power spectrum is found to cause widespread baryon collapse earlier than standard ΛCDM, leading to earlier gas heating. It also results in higher spin temperature of the baryons in the 21 cm line relative to ΛCDM at redshifts z>20 if the mass of the minihalo is larger than 1M · . It is estimated that experiments probing 21 cm radiation at high redshift will contribute a significant constraint on dark matter models of this type for initial minihalos larger than ∼10M · . These experiments may also detect (or rule out) primordial black holes as the dark matter in the window 30M · H 3 M · still left open by strong microlensing experiments and other astrophysical constraints. Early experiments reaching to z≅15 will constrain minihalos down to ∼10 3 M ·

  11. Particle Dark Matter constraints: the effect of Galactic uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Benito, Maria; Bernal, Nicolás; Iocco, Fabio [ICTP South American Institute for Fundamental Research Instituto de Física Teórica - Universidade Estadual Paulista (UNESP) Rua Dr. Bento Teobaldo Ferraz 271, 01140-070 São Paulo, SP Brazil (Brazil); Bozorgnia, Nassim; Calore, Francesca, E-mail: mariabenitocst@gmail.com, E-mail: nicolas.bernal@uan.edu.co, E-mail: n.bozorgnia@uva.nl, E-mail: calore@lapth.cnrs.fr, E-mail: fabio.iocco.astro@gmail.com [GRAPPA Institute, Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands)

    2017-02-01

    Collider, space, and Earth based experiments are now able to probe several extensions of the Standard Model of particle physics which provide viable dark matter candidates. Direct and indirect dark matter searches rely on inputs of astrophysical nature, such as the local dark matter density or the shape of the dark matter density profile in the target in object. The determination of these quantities is highly affected by astrophysical uncertainties. The latter, especially those for our own Galaxy, are ill-known, and often not fully accounted for when analyzing the phenomenology of particle physics models. In this paper we present a systematic, quantitative estimate of how astrophysical uncertainties on Galactic quantities (such as the local galactocentric distance, circular velocity, or the morphology of the stellar disk and bulge) propagate to the determination of the phenomenology of particle physics models, thus eventually affecting the determination of new physics parameters. We present results in the context of two specific extensions of the Standard Model (the Singlet Scalar and the Inert Doublet) that we adopt as case studies for their simplicity in illustrating the magnitude and impact of such uncertainties on the parameter space of the particle physics model itself. Our findings point toward very relevant effects of current Galactic uncertainties on the determination of particle physics parameters, and urge a systematic estimate of such uncertainties in more complex scenarios, in order to achieve constraints on the determination of new physics that realistically include all known uncertainties.

  12. Conversion of Gravitons into Dark Photons in Cosmological Dark Magnetic Fields

    OpenAIRE

    Masaki, Emi; Soda, Jiro

    2018-01-01

    It is well known that gravitons can convert into photons, and vice versa, in the presence of cosmological magnetic fields. We study this conversion process in the context of atomic dark matter scenario. In this scenario, we can expect cosmological dark magnetic fields, which are free from the stringent constraint from the cosmic microwave observations. We find that gravitons can effectively convert into dark photons in the presence of cosmological dark magnetic fields. The graviton-dark photo...

  13. Heavy spin-2 Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Babichev, Eugeny [Laboratoire de Physique Théorique, CNRS, Univ. Paris-Sud, Université Paris-Saclay,91405 Orsay (France); UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, GReCO,98bis boulevard Arago, F-75014 Paris (France); Marzola, Luca; Raidal, Martti [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Laboratory of Theoretical Physics, Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Schmidt-May, Angnis [Institut für Theoretische Physik, Eidgenössische Technische Hochschule Zürich,Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland); Urban, Federico; Veermäe, Hardi [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Strauss, Mikael von [UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, GReCO,98bis boulevard Arago, F-75014 Paris (France)

    2016-09-12

    We provide further details on a recent proposal addressing the nature of the dark sectors in cosmology and demonstrate that all current observations related to Dark Matter can be explained by the presence of a heavy spin-2 particle. Massive spin-2 fields and their gravitational interactions are uniquely described by ghost-free bimetric theory, which is a minimal and natural extension of General Relativity. In this setup, the largeness of the physical Planck mass is naturally related to extremely weak couplings of the heavy spin-2 field to baryonic matter and therefore explains the absence of signals in experiments dedicated to Dark Matter searches. It also ensures the phenomenological viability of our model as we confirm by comparing it with cosmological and local tests of gravity. At the same time, the spin-2 field possesses standard gravitational interactions and it decays universally into all Standard Model fields but not into massless gravitons. Matching the measured DM abundance together with the requirement of stability constrains the spin-2 mass to be in the 1 to 100 TeV range.

  14. Wanted! Nuclear Data for Dark Matter Astrophysics

    International Nuclear Information System (INIS)

    Gondolo, P.

    2014-01-01

    Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the known particles, and many theories postulate it as a new elementary particle. Searches for dark matter particles are under way: production at high-energy accelerators, direct detection through dark matter-nucleus scattering, indirect detection through cosmic rays, gamma rays, or effects on stars. Particle dark matter searches rely on observing an excess of events above background, and a lot of controversies have arisen over the origin of observed excesses. With the new high-quality cosmic ray measurements from the AMS-02 experiment, the major uncertainty in modeling cosmic ray fluxes is in the nuclear physics cross sections for spallation and fragmentation of cosmic rays off interstellar hydrogen and helium. The understanding of direct detection backgrounds is limited by poor knowledge of cosmic ray activation in detector materials, with order of magnitude differences between simulation codes. A scarcity of data on nucleon spin densities blurs the connection between dark matter theory and experiments. What is needed, ideally, are more and better measurements of spallation cross sections relevant to cosmic rays and cosmogenic activation, and data on the nucleon spin densities in nuclei

  15. Neutrino Oscillations as a Probe of Light Scalar Dark Matter.

    Science.gov (United States)

    Berlin, Asher

    2016-12-02

    We consider a class of models involving interactions between ultralight scalar dark matter and standard model neutrinos. Such couplings modify the neutrino mass splittings and mixing angles to include additional components that vary in time periodically with a frequency and amplitude set by the mass and energy density of the dark matter. Null results from recent searches for anomalous periodicities in the solar neutrino flux strongly constrain the dark matter-neutrino coupling to be orders of magnitude below current and projected limits derived from observations of the cosmic microwave background.

  16. Linear scale bounds on dark matter--dark radiation interactions and connection with the small scale crisis of cold dark matter

    DEFF Research Database (Denmark)

    Hannestad, Steen; Archidiacono, Maria; Bohr, Sebastian

    2017-01-01

    One of the open questions in modern cosmology is the small scale crisis of the cold dark matter paradigm. Increasing attention has recently been devoted to self-interacting dark matter models as a possible answer. However, solving the so-called "missing satellites" problem requires in addition...... the presence of an extra relativistic particle (dubbed dark radiation) scattering with dark matter in the early universe. Here we investigate the impact of different theoretical models devising dark matter dark radiation interactions on large scale cosmological observables. We use cosmic microwave background...... data to put constraints on the dark radiation component and its coupling to dark matter. We find that the values of the coupling allowed by the data imply a cut-off scale of the halo mass function consistent with the one required to match the observations of satellites in the Milky Way....

  17. H I and dust in the high latitude dark cloud L1642

    International Nuclear Information System (INIS)

    Liljestroem, T.; Mattila, K.

    1989-01-01

    The high latitude dark cloud L1642 in the 21 cm H I region was mapped using a 100 m radio telescope. A remarkable H I line broadening from 2.5 to 2.9 km/s is observed over a small area on the bright side of L1642, i.e., the side facing the galactic plane. Results are presented concerning the effects of the asymmetrical UV radiation field of OB stars on the H I gas and the very small dust grains associated with L1642

  18. Radial oscillations of strange quark stars admixed with condensed dark matter

    Science.gov (United States)

    Panotopoulos, G.; Lopes, Ilídio

    2017-10-01

    We compute the 20 lowest frequency radial oscillation modes of strange stars admixed with condensed dark matter. We assume a self-interacting bosonic dark matter, and we model dark matter inside the star as a Bose-Einstein condensate. In this case the equation of state is a polytropic one with index 1 +1 /n =2 and a constant K that is computed in terms of the mass of the dark matter particle and the scattering length. Assuming a mass and a scattering length compatible with current observational bounds for self-interacting dark matter, we have integrated numerically first the Tolman-Oppenheimer-Volkoff equations for the hydrostatic equilibrium, and then the equations for the perturbations ξ =Δ r /r and η =Δ P /P . For a compact object with certain mass and radius we have considered here three cases, namely no dark matter at all and two different dark matter scenarios. Our results show that (i) the separation between consecutive modes increases with the amount of dark matter, and (ii) the effect is more pronounced for higher order modes. These effects are relevant even for a strange star made of 5% dark matter.

  19. Unifying dark energy and dark matter with the modified Ricci model

    International Nuclear Information System (INIS)

    Zhang, Linsen; Wu, Puxun; Yu, Hongwei

    2011-01-01

    In this paper, two modified Ricci models are considered as the candidates of unified dark matter-dark energy. In model one, the energy density is given by ρ MR =3M pl (αH 2 + βH), whereas, in model two, by ρ MR =3M pl ((α)/(6)R + γH H -1 ). We find that they can explain both dark matter and dark energy successfully. A constant equation of state of dark energy is obtained in model one, which means that it gives the same background evolution as the wCDM model, while model two can give an evolutionary equation of state of dark energy with the phantom divide line crossing in the near past. (orig.)

  20. The Dark Energy Survey: more than dark energy – an overview

    Energy Technology Data Exchange (ETDEWEB)

    Vikram, Vinu; Abbott, T; Abdalla, F. B.; Allam, S.; Aleksic, J.; Amara, A.; Bacon, D.; Balbinot, E.; Banerji, M.; Bechtol, K.; Benoit-Levy, A.

    2016-03-21

    This overview paper describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4 m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion, the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterize dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large-scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper, we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from ‘Science Verification’, and from the first, second and third seasons of observations), what DES can tell us about the Solar system, the Milky Way, galaxy evolution, quasars and other topics. In addition, we show that if the cosmological model is assumed to be Λ+cold dark matter, then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the discovery of 34 trans-Neptunian objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed).

  1. Why we need to see the dark matter to understand the dark energy

    OpenAIRE

    Kunz, Martin

    2007-01-01

    The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up some 20% of the total energy budget today, while the dark energy is responsible for about 75%. Here we show that these numbers are only robust for specific dark energy models and that in general we cannot measure the abundance of the dark constituents sepa...

  2. Dark energy with fine redshift sampling

    Science.gov (United States)

    Linder, Eric V.

    2007-03-01

    The cosmological constant and many other possible origins for acceleration of the cosmic expansion possess variations in the dark energy properties slow on the Hubble time scale. Given that models with more rapid variation, or even phase transitions, are possible though, we examine the fineness in redshift with which cosmological probes can realistically be employed, and what constraints this could impose on dark energy behavior. In particular, we discuss various aspects of baryon acoustic oscillations, and their use to measure the Hubble parameter H(z). We find that currently considered cosmological probes have an innate resolution no finer than Δz≈0.2 0.3.

  3. Dark energy with fine redshift sampling

    International Nuclear Information System (INIS)

    Linder, Eric V.

    2007-01-01

    The cosmological constant and many other possible origins for acceleration of the cosmic expansion possess variations in the dark energy properties slow on the Hubble time scale. Given that models with more rapid variation, or even phase transitions, are possible though, we examine the fineness in redshift with which cosmological probes can realistically be employed, and what constraints this could impose on dark energy behavior. In particular, we discuss various aspects of baryon acoustic oscillations, and their use to measure the Hubble parameter H(z). We find that currently considered cosmological probes have an innate resolution no finer than Δz≅0.2-0.3

  4. arXiv Exponentially Light Dark Matter from Coannihilation

    CERN Document Server

    D'Agnolo, Raffaele Tito; Ruderman, Joshua T.; Wang, Po-Jen

    Dark matter may be a thermal relic whose abundance is set by mutual annihilations among multiple species. Traditionally, this coannihilation scenario has been applied to weak scale dark matter that is highly degenerate with other states. We show that coannihilation among states with split masses points to dark matter that is exponentially lighter than the weak scale, down to the keV scale. We highlight the regime where dark matter does not participate in the annihilations that dilute its number density. In this "sterile coannihilation" limit, the dark matter relic density is independent of its couplings, implying a broad parameter space of thermal relic targets for future experiments. Light dark matter from coannihilation evades stringent bounds from the cosmic microwave background, but will be tested by future direct detection, fixed target, and long-lived particle experiments.

  5. Constraining heavy dark matter with cosmic-ray antiprotons

    Science.gov (United States)

    Cuoco, Alessandro; Heisig, Jan; Korsmeier, Michael; Krämer, Michael

    2018-04-01

    Cosmic-ray observations provide a powerful probe of dark matter annihilation in the Galaxy. In this paper we derive constraints on heavy dark matter from the recent precise AMS-02 antiproton data. We consider all possible annihilation channels into pairs of standard model particles. Furthermore, we interpret our results in the context of minimal dark matter, including higgsino, wino and quintuplet dark matter. We compare the cosmic-ray antiproton limits to limits from γ-ray observations of dwarf spheroidal galaxies and to limits from γ-ray and γ-line observations towards the Galactic center. While the latter limits are highly dependent on the dark matter density distribution and only exclude a thermal wino for cuspy profiles, the cosmic-ray limits are more robust, strongly disfavoring the thermal wino dark matter scenario even for a conservative estimate of systematic uncertainties.

  6. Dark Energy, Dark Matter and Science with Constellation-X

    Science.gov (United States)

    Cardiff, Ann Hornschemeier

    2005-01-01

    Constellation-X, with more than 100 times the collecting area of any previous spectroscopic mission operating in the 0.25-40 keV bandpass, will enable highthroughput, high spectral resolution studies of sources ranging from the most luminous accreting supermassive black holes in the Universe to the disks around young stars where planets form. This talk will review the updated Constellation-X science case, released in booklet form during summer 2005. The science areas where Constellation-X will have major impact include the exploration of the space-time geometry of black holes spanning nine orders of magnitude in mass and the nature of the dark energy and dark matter which govern the expansion and ultimate fate of the Universe. Constellation-X will also explore processes referred to as "cosmic feedback" whereby mechanical energy, radiation, and chemical elements from star formation and black holes are returned to interstellar and intergalactic medium, profoundly affecting the development of structure in the Universe, and will also probe all the important life cycles of matter, from stellar and planetary birth to stellar death via supernova to stellar endpoints in the form of accreting binaries and supernova remnants. This talk will touch upon all these areas, with particular emphasis on Constellation-X's role in the study of Dark Energy.

  7. Serendipity in dark photon searches

    Science.gov (United States)

    Ilten, Philip; Soreq, Yotam; Williams, Mike; Xue, Wei

    2018-06-01

    Searches for dark photons provide serendipitous discovery potential for other types of vector particles. We develop a framework for recasting dark photon searches to obtain constraints on more general theories, which includes a data-driven method for determining hadronic decay rates. We demonstrate our approach by deriving constraints on a vector that couples to the B-L current, a leptophobic B boson that couples directly to baryon number and to leptons via B- γ kinetic mixing, and on a vector that mediates a protophobic force. Our approach can easily be generalized to any massive gauge boson with vector couplings to the Standard Model fermions, and software to perform any such recasting is provided at https://gitlab.com/philten/darkcast https://gitlab.com/philten/darkcast" TargetType="URL"/> .

  8. Radiative inflation and dark energy

    International Nuclear Information System (INIS)

    Di Bari, Pasquale; King, Stephen F.; Luhn, Christoph; Merle, Alexander; Schmidt-May, Angnis

    2011-01-01

    We propose a model based on radiative symmetry breaking that combines inflation with dark energy and is consistent with the Wilkinson Microwave Anisotropy Probe 7-year regions. The radiative inflationary potential leads to the prediction of a spectral index 0.955 S < or approx. 0.967 and a tensor to scalar ratio 0.142 < or approx. r < or approx. 0.186, both consistent with current data but testable by the Planck experiment. The radiative symmetry breaking close to the Planck scale gives rise to a pseudo Nambu-Goldstone boson with a gravitationally suppressed mass which can naturally play the role of a quintessence field responsible for dark energy. Finally, we present a possible extra dimensional scenario in which our model could be realized.

  9. High CO/sub 2/ partial pressure effects on dark and light CO/sub 2/ fixation and metabolism in Vicia faba leaves

    Energy Technology Data Exchange (ETDEWEB)

    Coudret, A.; Ferron, F.; Laffray, D.

    1985-01-01

    Stomatal opening on Vicia faba can be induced by high CO/sub 2/ partial pressures (10.2%) in dark as well as in light. Stomatal aperture was measured in both cases with a hydrogen porometer. The distribution of /sup 14/C among early products of photosynthesis was studied. Comparisons are made with carboxylations occurring when stomata were open in the dark with CO/sub 2/-free air and in light with 0.034% CO/sub 2/. Results showed that in high CO/sub 2/ partial pressure in light, less radioactivity was incorporated in Calvin cycle intermediates and more in sucrose. ..beta.. carboxylations and photorespiration seemed to be inhibited. In the dark in both CO/sub 2/ conditions, /sup 14/C incorporation was found in malate and aspartate but also in serine and glycerate in high CO/sub 2/ conditions. In light these changes in metabolic pathways may be related with the deleterious effects recorded on leaves after long-term expositions to high partial pressure of CO/sub 2/.

  10. Why we need to see the dark matter to understand the dark energy

    International Nuclear Information System (INIS)

    Kunz, M

    2008-01-01

    Abstract. The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up some 20% of the total energy budget today, while the dark energy is responsible for about 75%. Here we show that these numbers are only robust for specific dark energy models and that in general we cannot measure the abundance of the dark constituents separately without making strong assumptions

  11. HST images of dark giants as dark matter: Part.I The black cocoon stars of Carina Nebula region

    International Nuclear Information System (INIS)

    Celis, S.L.

    2001-01-01

    In an evolutionary scenario, the existence of isolated dark giant objects known as Post M latest spectral type stars (1) (or black cocoon stars) are in the last stage of their life and, as extremely advanced old age objects, they cease to be stars. The photographic images of Carina nebula taken by the Hubble Space Telescope (HST) have been used to detect the post M-Iatest stars as dark silhouettes. The luminosity attenuation equation of M late stars (1), A = αS 3 , points out the baryonic dark matter envelopes the oldest red giants that produce earlier dark giants. This equation says that when the red giant star finishes to produce baryonic dark matter, the central star is extinguishing and transforms into dark giants and dusty globules that disperse cool gaseous matter into the interstellar space. These old dark objects have a size from 400 to 600 astronomical units (AU). The advanced dark giants, the dusty dark giants, might not contain a star within the molecular cloud that envelops it. In this case, the dark giants might produce the smaller and less massive dark globules of the Thackeray's globules type (less than 4 solar masses) where, Reupurth et al. (2) found that these globules are now in an advanced stage of disintegration and they found no evidence of star formation in any of these objects. The high-resolution of the Hubble images allows: The observation of isolated dark giants, dusty globules with central dark giants, the observation of partial eclipses or transiting of giant stars and the estimation of linear and angular diameters (ionised cocoons) of giant stellar objects. The dark giants of the image are identified them as objects with observed angular diameter. The large quantity of dark giants in a small sector of the sky suggests that they are densely populated (population stars III) and ubiquitous in the galactic disc. They can be located in isolated form or associated in dense Conglomerations of dark giants. At the same time, conglomerates of

  12. Acceleration of the universe dark energy or modified

    International Nuclear Information System (INIS)

    Cardenas, Rolando; Leyva, Yoelsy

    2007-01-01

    We present a composite model of dark energy, motivated in string and quantum field theory considerations. Then we speak on gravity theories in which the gravity Lagrangian is modified, resulting in a modification of General Relativity. We outline a methodology allowing a mapping between these two theories, i. e., both dark energy models and modified gravity can give the same cosmological dynamics. We apply aforementioned methodology to obtain the mapping composite dark energy-modified gravity for a particular case. Cosmic expansion history takes into account very large scales, the homogeneous Universe, and can not discriminate between above two theories. However, cosmic growth history takes into consideration intermediate cluster and galactic scales, the inhomogeneous Universe, and there might be the clue to discriminate whether the current acceleration of the Universe is because it is filled with a new fluid having repulsive gravity (dark energy) or it is just that gravity gets weaker and long scales (modified gravity). (Author)

  13. Academic Training: Search for Dark Matter - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    28, 29, 30 June, 1 & 2 July ACADEMIC TRAINING LECTURE REGULAR PROGRAMME From 11:00 hrs - 28, 29 June, 1, 2 July, Main Auditorium bldg. 500. 30 June, Council Chamber bldg. 503 Search for Dark Matter B. Sadoulet / Univ. of California, Berkeley, USA In the first lecture, I will review the most recent cosmological evidence for the pervading dark matter in the universe and the emerging consensus that it is not ordinary matter. We will then focus on thermal particle candidates, which may have been produced in the hot early universe and stayed around to constitute dark matter: neutrinos and Weakly Interacting Massive Particles (WIMPs). I will emphasize what can be learnt from cosmology (e.g. the evidence for cold dark matter and the limits on neutrino masses). The third and the fourth lectures will be devoted the direct detection of WIMPs, its technical challenges and the present status. I will describe the recent advances from phonon-mediated detectors which currently provide the best limits and revi...

  14. Dark Energy from structure: a status report

    Science.gov (United States)

    Buchert, Thomas

    2008-02-01

    The effective evolution of an inhomogeneous universe model in any theory of gravitation may be described in terms of spatially averaged variables. In Einstein’s theory, restricting attention to scalar variables, this evolution can be modeled by solutions of a set of Friedmann equations for an effective volume scale factor, with matter and backreaction source terms. The latter can be represented by an effective scalar field (“morphon field”) modeling Dark Energy. The present work provides an overview over the Dark Energy debate in connection with the impact of inhomogeneities, and formulates strategies for a comprehensive quantitative evaluation of backreaction effects both in theoretical and observational cosmology. We recall the basic steps of a description of backreaction effects in relativistic cosmology that lead to refurnishing the standard cosmological equations, but also lay down a number of challenges and unresolved issues in connection with their observational interpretation. The present status of this subject is intermediate: we have a good qualitative understanding of backreaction effects pointing to a global instability of the standard model of cosmology; exact solutions and perturbative results modeling this instability lie in the right sector to explain Dark Energy from inhomogeneities. It is fair to say that, even if backreaction effects turn out to be less important than anticipated by some researchers, the concordance high-precision cosmology, the architecture of current N-body simulations, as well as standard perturbative approaches may all fall short in correctly describing the Late Universe.

  15. Interacting Agegraphic Dark Energy

    OpenAIRE

    Wei, Hao; Cai, Rong-Gen

    2007-01-01

    A new dark energy model, named "agegraphic dark energy", has been proposed recently, based on the so-called K\\'{a}rolyh\\'{a}zy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegrap...

  16. Searching for light dark matter with the SLAC millicharge experiment.

    Science.gov (United States)

    Diamond, M; Schuster, P

    2013-11-27

    New sub-GeV gauge forces ("dark photons") that kinetically mix with the photon provide a promising scenario for MeV-GeV dark matter and are the subject of a program of searches at fixed-target and collider facilities around the world. In such models, dark photons produced in collisions may decay invisibly into dark-matter states, thereby evading current searches. We reexamine results of the SLAC mQ electron beam dump experiment designed to search for millicharged particles and find that it was strongly sensitive to any secondary beam of dark matter produced by electron-nucleus collisions in the target. The constraints are competitive for dark photon masses in the ~1-30 MeV range, covering part of the parameter space that can reconcile the apparent (g-2)(μ) anomaly. Simple adjustments to the original SLAC search for millicharges may extend sensitivity to cover a sizable portion of the remaining (g-2)(μ) anomaly-motivated region. The mQ sensitivity is therefore complementary to ongoing searches for visible decays of dark photons. Compared to existing direct-detection searches, mQ sensitivity to electron-dark-matter scattering cross sections is more than an order of magnitude better for a significant range of masses and couplings in simple models.

  17. Can tonne-scale direct detection experiments discover nuclear dark matter?

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Alistair; Kirk, Russell; Monroe, Jocelyn; West, Stephen M., E-mail: Alistair.Butcher.2010@live.rhul.ac.uk, E-mail: Russell.Kirk.2008@live.rhul.ac.uk, E-mail: Jocelyn.Monroe@rhul.ac.uk, E-mail: Stephen.West@rhul.ac.uk [Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX (United Kingdom)

    2017-10-01

    Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with a decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the 3 σ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a 2 σ distinction is possible by these experiments individually, while 3 σ sensitivity is reached for a range of parameters by the combination of the two experiments. We show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a WIMP at greater than 3 σ .

  18. Can tonne-scale direct detection experiments discover nuclear dark matter?

    International Nuclear Information System (INIS)

    Butcher, Alistair; Kirk, Russell; Monroe, Jocelyn; West, Stephen M.

    2017-01-01

    Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with a decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the 3 σ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a 2 σ distinction is possible by these experiments individually, while 3 σ sensitivity is reached for a range of parameters by the combination of the two experiments. We show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a WIMP at greater than 3 σ .

  19. Neutrinos and dark energy

    International Nuclear Information System (INIS)

    Schrempp, L.

    2008-02-01

    From the observed late-time acceleration of cosmic expansion arises the quest for the nature of Dark Energy. As has been widely discussed, the cosmic neutrino background naturally qualifies for a connection with the Dark Energy sector and as a result could play a key role for the origin of cosmic acceleration. In this thesis we explore various theoretical aspects and phenomenological consequences arising from non-standard neutrino interactions, which dynamically link the cosmic neutrino background and a slowly-evolving scalar field of the dark sector. In the considered scenario, known as Neutrino Dark Energy, the complex interplay between the neutrinos and the scalar field not only allows to explain cosmic acceleration, but intriguingly, as a distinct signature, also gives rise to dynamical, time-dependent neutrino masses. In a first analysis, we thoroughly investigate an astrophysical high energy neutrino process which is sensitive to neutrino masses. We work out, both semi-analytically and numerically, the generic clear-cut signatures arising from a possible time variation of neutrino masses which we compare to the corresponding results for constant neutrino masses. Finally, we demonstrate that even for the lowest possible neutrino mass scale, it is feasible for the radio telescope LOFAR to reveal a variation of neutrino masses and therefore to probe the nature of Dark Energy within the next decade. A second independent analysis deals with the recently challenged stability of Neutrino Dark Energy against the strong growth of hydrodynamic perturbations, driven by the new scalar force felt between neutrinos. Within the framework of linear cosmological perturbation theory, we derive the equation of motion of the neutrino perturbations in a model-independent way. This equation allows to deduce an analytical stability condition which translates into a comfortable upper bound on the scalar-neutrino coupling which is determined by the ratio of the densities in cold dark

  20. Neutrinos and dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Schrempp, L.

    2008-02-15

    From the observed late-time acceleration of cosmic expansion arises the quest for the nature of Dark Energy. As has been widely discussed, the cosmic neutrino background naturally qualifies for a connection with the Dark Energy sector and as a result could play a key role for the origin of cosmic acceleration. In this thesis we explore various theoretical aspects and phenomenological consequences arising from non-standard neutrino interactions, which dynamically link the cosmic neutrino background and a slowly-evolving scalar field of the dark sector. In the considered scenario, known as Neutrino Dark Energy, the complex interplay between the neutrinos and the scalar field not only allows to explain cosmic acceleration, but intriguingly, as a distinct signature, also gives rise to dynamical, time-dependent neutrino masses. In a first analysis, we thoroughly investigate an astrophysical high energy neutrino process which is sensitive to neutrino masses. We work out, both semi-analytically and numerically, the generic clear-cut signatures arising from a possible time variation of neutrino masses which we compare to the corresponding results for constant neutrino masses. Finally, we demonstrate that even for the lowest possible neutrino mass scale, it is feasible for the radio telescope LOFAR to reveal a variation of neutrino masses and therefore to probe the nature of Dark Energy within the next decade. A second independent analysis deals with the recently challenged stability of Neutrino Dark Energy against the strong growth of hydrodynamic perturbations, driven by the new scalar force felt between neutrinos. Within the framework of linear cosmological perturbation theory, we derive the equation of motion of the neutrino perturbations in a model-independent way. This equation allows to deduce an analytical stability condition which translates into a comfortable upper bound on the scalar-neutrino coupling which is determined by the ratio of the densities in cold dark

  1. Dark matter admixed strange quark stars in the Starobinsky model

    Science.gov (United States)

    Lopes, Ilídio; Panotopoulos, Grigoris

    2018-01-01

    We compute the mass-to-radius profiles for dark matter admixed strange quark stars in the Starobinsky model of modified gravity. For quark matter, we assume the MIT bag model, while self-interacting dark matter inside the star is modeled as a Bose-Einstein condensate with a polytropic equation of state. We numerically integrate the structure equations in the Einstein frame, adopting the two-fluid formalism, and we treat the curvature correction term nonperturbatively. The effects on the properties of the stars of the amount of dark matter as well as the higher curvature term are investigated. We find that strange quark stars (in agreement with current observational constraints) with the highest masses are equally affected by dark matter and modified gravity.

  2. Detecting dark matter

    International Nuclear Information System (INIS)

    Dixon, Roger L.

    2000-01-01

    Dark matter is one of the most pressing problems in modern cosmology and particle physic research. This talk will motivate the existence of dark matter by reviewing the main experimental evidence for its existence, the rotation curves of galaxies and the motions of galaxies about one another. It will then go on to review the corroborating theoretical motivations before combining all the supporting evidence to explore some of the possibilities for dark matter along with its expected properties. This will lay the ground work for dark matter detection. A number of differing techniques are being developed and used to detect dark matter. These will be briefly discussed before the focus turns to cryogenic detection techniques. Finally, some preliminary results and expectations will be given for the Cryogenic Dark Matter Search (CDMS) experiment

  3. Dark Matter candidates in a baryogenesis inspired scenario

    International Nuclear Information System (INIS)

    Provenza, A; Quiros, M; Ullio, P

    2006-01-01

    It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upcoming experiments. We find, contrary to the standard lore, that indirect detection searches are more promising than direct ones, and they already exclude part of the parameter space

  4. Loop-induced dark matter direct detection signals from gamma-ray lines

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal; Haisch, Ulrich; Kahlhoefer, Felix

    2012-01-01

    Improved limits as well as tentative claims for dark matter annihilation into gamma-ray lines have been presented recently. We study the direct detection cross section induced from dark matter annihilation into two photons in a model-independent fashion, assuming no additional couplings between...... dark matter and nuclei. We find a striking non-standard recoil spectrum due to different destructively interfering contributions to the dark matter nucleus scattering cross section. While in the case of s-wave annihilation the current sensitivity of direct detection experiments is insufficient...... to compete with indirect detection searches, for p-wave annihilation the constraints from direct searches are comparable. This will allow to test dark matter scenarios with p-wave annihilation that predict a large di-photon annihilation cross section in the next generation of experiments....

  5. Dark matter and dark energy a challenge for modern cosmology

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Matarrese, Sabino

    2011-01-01

    This book brings together reviews from leading international authorities on the developments in the study of dark matter and dark energy, as seen from both their cosmological and particle physics side. Studying the physical and astrophysical properties of the dark components of our Universe is a crucial step towards the ultimate goal of unveiling their nature. The work developed from a doctoral school sponsored by the Italian Society of General Relativity and Gravitation. The book starts with a concise introduction to the standard cosmological model, as well as with a presentation of the theory of linear perturbations around a homogeneous and isotropic background. It covers the particle physics and cosmological aspects of dark matter and (dynamical) dark energy, including a discussion of how modified theories of gravity could provide a possible candidate for dark energy. A detailed presentation is also given of the possible ways of testing the theory in terms of cosmic microwave background, galaxy redshift su...

  6. Leptogenesis, Dark Energy, Dark Matter and the neutrinos

    International Nuclear Information System (INIS)

    Sarkar, Utpal

    2007-01-01

    In this review we discuss how the models of neutrino masses can accommodate solutions to the problem of matter-antimatter asymmetry in the universe, dark energy or cosmological constant problem and dark matter candidates. The matter-antimatter asymmetry is explained by leptogenesis, originating from the lepton number violation associated with the neutrino masses. The dark energy problem is correlated with a mass varying neutrinos, which could originate from a pseudo-Nambu-Goldstone boson. In some radiative models of neutrino masses, there exists a Higgs doublet that does not acquire any vacuum expectation value. This field could be inert and the lightest inert particle could then be a dark matter candidate. We reviewed these scenarios in connection with models of neutrino masses with right-handed neutrinos and with triplet Higgs scalars

  7. Dark Matter "Collider" from Inelastic Boosted Dark Matter.

    Science.gov (United States)

    Kim, Doojin; Park, Jong-Chul; Shin, Seodong

    2017-10-20

    We propose a novel dark matter (DM) detection strategy for models with a nonminimal dark sector. The main ingredients in the underlying DM scenario are a boosted DM particle and a heavier dark sector state. The relativistic DM impinged on target material scatters off inelastically to the heavier state, which subsequently decays into DM along with lighter states including visible (standard model) particles. The expected signal event, therefore, accompanies a visible signature by the secondary cascade process associated with a recoiling of the target particle, differing from the typical neutrino signal not involving the secondary signature. We then discuss various kinematic features followed by DM detection prospects at large-volume neutrino detectors with a model framework where a dark gauge boson is the mediator between the standard model particles and DM.

  8. Dark side of the Higgs boson

    International Nuclear Information System (INIS)

    Low, I.; Schwaller, P.; Shaughnessy, G.; Wagner, C.E.M.

    2012-01-01

    Current limits from the Large Hadron Collider exclude a standard model-like Higgs mass above 150 GeV, by placing an upper bound on the Higgs production rate. We emphasize that, alternatively, the limit could be interpreted as a lower bound on the total decay width of the Higgs boson. If the invisible decay width of the Higgs is of the same order as the visible decay width, a heavy Higgs boson could be consistent with null results from current searches. We propose a method to infer the invisible decay of the Higgs by using the width of the measured h → ZZ → 4 (ell) line shape, and study the effect on the width extraction due to a reduced signal strength. Assuming the invisible decay product is the dark matter, we show that minimal models are tightly constrained by limits from Higgs searches at the LHC and direct detection experiments of dark matter, unless the relic density constraint is relaxed.

  9. Advanced Dark Energy Physics Telescope (ADEPT)

    Energy Technology Data Exchange (ETDEWEB)

    Charles L. Bennett

    2009-03-26

    In 2006, we proposed to NASA a detailed concept study of ADEPT (the Advanced Dark Energy Physics Telescope), a potential space mission to reliably measure the time-evolution of dark energy by conducting the largest effective volume survey of the universe ever done. A peer-review panel of scientific, management, and technical experts reported back the highest possible 'excellent' rating for ADEPT. We have since made substantial advances in the scientific and technical maturity of the mission design. With this Department of Energy (DOE) award we were granted supplemental funding to support specific extended research items that were not included in the NASA proposal, many of which were intended to broadly advance future dark energy research, as laid out by the Dark Energy Task Force (DETF). The proposed work had three targets: (1) the adaptation of large-format infrared arrays to a 2 micron cut-off; (2) analytical research to improve the understanding of the dark energy figure-of- merit; and (3) extended studies of baryon acoustic oscillation systematic uncertainties. Since the actual award was only for {approx}10% of the proposed amount item (1) was dropped and item (2) work was severely restricted, consistent with the referee reviews of the proposal, although there was considerable contradictions between reviewer comments and several comments that displayed a lack of familiarity with the research. None the less, item (3) was the focus of the work. To characterize the nature of the dark energy, ADEPT is designed to observe baryon acoustic oscillations (BAO) in a large galaxy redshift survey and to obtain substantial numbers of high-redshift Type Ia supernovae (SNe Ia). The 2003 Wilkinson Microwave Anisotropy Probe (WMAP) made a precise determination of the BAO 'standard ruler' scale, as it was imprinted on the cosmic microwave background (CMB) at z {approx} 1090. The standard ruler was also imprinted on the pattern of galaxies, and was first

  10. High-Average, High-Peak Current Injector Design

    CERN Document Server

    Biedron, S G; Virgo, M

    2005-01-01

    There is increasing interest in high-average-power (>100 kW), um-range FELs. These machines require high peak current (~1 kA), modest transverse emittance, and beam energies of ~100 MeV. High average currents (~1 A) place additional constraints on the design of the injector. We present a design for an injector intended to produce the required peak currents at the injector, eliminating the need for magnetic compression within the linac. This reduces the potential for beam quality degradation due to CSR and space charge effects within magnetic chicanes.

  11. A dark energy multiverse

    International Nuclear Information System (INIS)

    Robles-Perez, Salvador; Martin-Moruno, Prado; Rozas-Fernandez, Alberto; Gonzalez-Diaz, Pedro F

    2007-01-01

    We present cosmic solutions corresponding to universes filled with dark and phantom energy, all having a negative cosmological constant. All such solutions contain infinite singularities, successively and equally distributed along time, which can be either big bang/crunches or big rips singularities. Classically these solutions can be regarded as associated with multiverse scenarios, being those corresponding to phantom energy that may describe the current accelerating universe. (fast track communication)

  12. A dark energy multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Robles-Perez, Salvador; Martin-Moruno, Prado; Rozas-Fernandez, Alberto; Gonzalez-Diaz, Pedro F [Colina de los Chopos, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones CientIficas, Serrano 121, 28006 Madrid (Spain)

    2007-05-21

    We present cosmic solutions corresponding to universes filled with dark and phantom energy, all having a negative cosmological constant. All such solutions contain infinite singularities, successively and equally distributed along time, which can be either big bang/crunches or big rips singularities. Classically these solutions can be regarded as associated with multiverse scenarios, being those corresponding to phantom energy that may describe the current accelerating universe. (fast track communication)

  13. Intense gamma-ray lines from hidden vector dark matter decay

    International Nuclear Information System (INIS)

    Arina, Chiara; Hambye, Thomas

    2009-12-01

    Scenarios with hidden, spontaneously broken, non-abelian gauge groups contain a natural dark matter candidate, the hidden vector, whose longevity is due to an accidental custodial symmetry in the renormalizable Lagrangian. Nevertheless, non-renormalizable dimension six operators break the custodial symmetry and induce the decay of the dark matter particle at cosmological times. We discuss in this paper the cosmic ray signatures of this scenario and we show that the decay of hidden vector dark matter particles generically produce an intense gamma ray line which could be observed by the Fermi-LAT experiment, if the scale of custodial symmetry breaking is close to the Grand Unification scale. This gamma line proceeds directly from a tree level dark matter 2-body decay in association with a Higgs boson. Within this model we also perform a determination of the relic density constraints taking into account the dark matter annihilation processes with one dark matter particle in the final state. The corresponding direct detection rates can be easily of order the current experimental sensitivities. (orig.)

  14. Intense gamma-ray lines from hidden vector dark matter decay

    Energy Technology Data Exchange (ETDEWEB)

    Arina, Chiara; Hambye, Thomas [Universite Libre de Bruxelles (Belgium). Service de Physique Theorique; Ibarra, Alejandro [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Weniger, Christoph [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2009-12-15

    Scenarios with hidden, spontaneously broken, non-abelian gauge groups contain a natural dark matter candidate, the hidden vector, whose longevity is due to an accidental custodial symmetry in the renormalizable Lagrangian. Nevertheless, non-renormalizable dimension six operators break the custodial symmetry and induce the decay of the dark matter particle at cosmological times. We discuss in this paper the cosmic ray signatures of this scenario and we show that the decay of hidden vector dark matter particles generically produce an intense gamma ray line which could be observed by the Fermi-LAT experiment, if the scale of custodial symmetry breaking is close to the Grand Unification scale. This gamma line proceeds directly from a tree level dark matter 2-body decay in association with a Higgs boson. Within this model we also perform a determination of the relic density constraints taking into account the dark matter annihilation processes with one dark matter particle in the final state. The corresponding direct detection rates can be easily of order the current experimental sensitivities. (orig.)

  15. Intense gamma-ray lines from hidden vector dark matter decay

    International Nuclear Information System (INIS)

    Arina, Chiara; Hambye, Thomas; Ibarra, Alejandro; Weniger, Christoph

    2010-01-01

    Scenarios with hidden, spontaneously broken, non-abelian gauge groups contain a natural dark matter candidate, the hidden vector, whose longevity is due to an accidental custodial symmetry in the renormalizable Lagrangian. Nevertheless, non-renormalizable dimension six operators break the custodial symmetry and induce the decay of the dark matter particle at cosmological times. We discuss in this paper the cosmic ray signatures of this scenario and we show that the decay of hidden vector dark matter particles generically produce an intense gamma ray line which could be observed by the Fermi-LAT experiment, if the scale of custodial symmetry breaking is close to the Grand Unification scale. This gamma line proceeds directly from a tree level dark matter 2-body decay in association with a Higgs boson. Within this model we also perform a determination of the relic density constraints taking into account the dark matter annihilation processes with one dark matter particle in the final state. The corresponding direct detection rates can be easily of order the current experimental sensitivities

  16. Quark seesaw mechanism, dark U (1 ) symmetry, and the baryon-dark matter coincidence

    Science.gov (United States)

    Gu, Pei-Hong; Mohapatra, Rabindra N.

    2017-09-01

    We attempt to understand the baryon-dark matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong C P problem. The S U (2 )L×S U (2 )R×U (1 )B -L gauge symmetry of this model is extended by a dark U (1 )X group plus inclusion of a heavy neutral vector-like fermion χL ,R charged under the dark group which plays the role of dark matter. All fermions are Dirac type in this model. Decay of heavy scalars charged under U (1 )X leads to simultaneous asymmetry generation of the dark matter and baryons after sphaleron effects are included. The U (1 )X group not only helps to stabilize the dark matter but also helps in the elimination of the symmetric part of the dark matter via χ -χ ¯ annihilation. For dark matter mass near the proton mass, it explains why the baryon and dark matter abundances are of similar magnitude (the baryon-dark matter coincidence problem). This model is testable in low threshold (sub-keV) direct dark matter search experiments.

  17. Self-interacting dark matter constraints in a thick dark disk scenario

    Science.gov (United States)

    Vattis, Kyriakos; Koushiappas, Savvas M.

    2018-05-01

    A thick dark matter disk is predicted in cold dark matter simulations as the outcome of the interaction between accreted satellites and the stellar disk in Milky Way-sized halos. We study the effects of a self-interacting thick dark disk on the energetic neutrino flux from the Sun. We find that for particle masses between 100 GeV and 1 TeV and dark matter annihilation to τ+τ-, either the self-interaction may not be strong enough to solve the small-scale structure motivation or a dark disk cannot be present in the Milky Way.

  18. Emergent Gravity and the Dark Universe

    Directory of Open Access Journals (Sweden)

    Erik P. Verlinde

    2017-05-01

    Full Text Available Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional 'dark' gravitational force describing the 'elastic' response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton's constant and the Hubble acceleration scale a_0 =cH_0, and provide evidence for the fact that this additional `dark gravity~force' explains the observed phenomena in galaxies and clusters currently attributed to dark matter.

  19. High PRF high current switch

    Science.gov (United States)

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

  20. An effective description of dark matter and dark energy in the mildly non-linear regime

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, Matthew; Senatore, Leonardo [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94306 (United States); Maleknejad, Azadeh, E-mail: matthew.lewandowski@cea.fr, E-mail: azade@ipm.ir, E-mail: senatore@stanford.edu [School of Physics, Institute for Research in Fundamental Sciences (IPM), P. Code. 19538-33511, Tehran (Iran, Islamic Republic of)

    2017-05-01

    In the next few years, we are going to probe the low-redshift universe with unprecedented accuracy. Among the various fruits that this will bear, it will greatly improve our knowledge of the dynamics of dark energy, though for this there is a strong theoretical preference for a cosmological constant. We assume that dark energy is described by the so-called Effective Field Theory of Dark Energy, which assumes that dark energy is the Goldstone boson of time translations. Such a formalism makes it easy to ensure that our signatures are consistent with well-established principles of physics. Since most of the information resides at high wavenumbers, it is important to be able to make predictions at the highest wavenumber that is possible. The Effective Field Theory of Large-Scale Structure (EFTofLSS) is a theoretical framework that has allowed us to make accurate predictions in the mildly non-linear regime. In this paper, we derive the non-linear equations that extend the EFTofLSS to include the effect of dark energy both on the matter fields and on the biased tracers. For the specific case of clustering quintessence, we then perturbatively solve to cubic order the resulting non-linear equations and construct the one-loop power spectrum of the total density contrast.

  1. Dark matter at the SHiP experiment

    International Nuclear Information System (INIS)

    Timiryasov, Inar

    2016-01-01

    We study prospects of dark matter searches in the SHiP experiment. SHiP (Search for Hidden Particles) is the recently proposed fixed target experiment which will exploit the high-intensity beam of 400 GeV protons from the CERN SPS. In addition to the hidden sector detector, SHiP will be equipped with the ν_τ detector, which presumably would be sensitive to dark matter particles. We describe appropriate production and detection channels and estimate SHiP’s sensitivity for a scalar dark matter coupled to the Standard model through the vector mediator

  2. Top-philic dark matter within and beyond the WIMP paradigm

    Science.gov (United States)

    Garny, Mathias; Heisig, Jan; Hufnagel, Marco; Lülf, Benedikt

    2018-04-01

    We present a comprehensive analysis of top-philic Majorana dark matter that interacts via a colored t -channel mediator. Despite the simplicity of the model—introducing three parameters only—it provides an extremely rich phenomenology allowing us to accommodate the relic density for a large range of coupling strengths spanning over 6 orders of magnitude. This model features all "exceptional" mechanisms for dark matter freeze-out, including the recently discovered conversion-driven freeze-out mode, with interesting signatures of long-lived colored particles at colliders. We constrain the cosmologically allowed parameter space with current experimental limits from direct, indirect and collider searches, with special emphasis on light dark matter below the top mass. In particular, we explore the interplay between limits from Xenon1T, Fermi-LAT and AMS-02 as well as limits from stop, monojet and Higgs invisible decay searches at the LHC. We find that several blind spots for light dark matter evade current constraints. The region in parameter space where the relic density is set by the mechanism of conversion-driven freeze-out can be conclusively tested by R -hadron searches at the LHC with 300 fb-1 .

  3. Self-interacting asymmetric dark matter coupled to a light massive dark photon

    International Nuclear Information System (INIS)

    Petraki, Kalliopi; Pearce, Lauren; Kusenko, Alexander

    2014-01-01

    Dark matter (DM) with sizeable self-interactions mediated by a light species offers a compelling explanation of the observed galactic substructure; furthermore, the direct coupling between DM and a light particle contributes to the DM annihilation in the early universe. If the DM abundance is due to a dark particle-antiparticle asymmetry, the DM annihilation cross-section can be arbitrarily large, and the coupling of DM to the light species can be significant. We consider the case of asymmetric DM interacting via a light (but not necessarily massless) Abelian gauge vector boson, a dark photon. In the massless dark photon limit, gauge invariance mandates that DM be multicomponent, consisting of positive and negative dark ions of different species which partially bind in neutral dark atoms. We argue that a similar conclusion holds for light dark photons; in particular, we establish that the multi-component and atomic character of DM persists in much of the parameter space where the dark photon is sufficiently light to mediate sizeable DM self-interactions. We discuss the cosmological sequence of events in this scenario, including the dark asymmetry generation, the freeze-out of annihilations, the dark recombination and the phase transition which gives mass to the dark photon. We estimate the effect of self-interactions in DM haloes, taking into account this cosmological history. We place constraints based on the observed ellipticity of large haloes, and identify the regimes where DM self-scattering can affect the dynamics of smaller haloes, bringing theory in better agreement with observations. Moreover, we estimate the cosmological abundance of dark photons in various regimes, and derive pertinent bounds

  4. Light dark Higgs boson in minimal sub-GeV dark matter scenarios

    Science.gov (United States)

    Darmé, Luc; Rao, Soumya; Roszkowski, Leszek

    2018-03-01

    Minimal scenarios with light (sub-GeV) dark matter whose relic density is obtained from thermal freeze-out must include new light mediators. In particular, a very well-motivated case is that of a new "dark" massive vector gauge boson mediator. The mass term for such mediator is most naturally obtained by a "dark Higgs mechanism" which leads to the presence of an often long-lived dark Higgs boson whose mass scale is the same as that of the mediator. We study the phenomenology and experimental constraints on two minimal, self-consistent dark sectors that include such a light dark Higgs boson. In one the dark matter is a pseudo-Dirac fermion, in the other a complex scalar. We find that the constraints from BBN and CMB are considerably relaxed in the framework of such minimal dark sectors. We present detection prospects for the dark Higgs boson in existing and projected proton beam-dump experiments. We show that future searches at experiments like Xenon1T or LDMX can probe all the relevant parameter space, complementing the various upcoming indirect constraints from astrophysical observations.

  5. Dark catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub, E-mail: prateekagrawal@fas.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: randall@physics.harvard.edu, E-mail: jscholtz@physics.harvard.edu [Department of Physics, Harvard University, 17 Oxford St., Cambridge, MA 02138 (United States)

    2017-08-01

    Recently it was shown that dark matter with mass of order the weak scale can be charged under a new long-range force, decoupled from the Standard Model, with only weak constraints from early Universe cosmology. Here we consider the implications of an additional charged particle C that is light enough to lead to significant dissipative dynamics on galactic times scales. We highlight several novel features of this model, which can be relevant even when the C particle constitutes only a small fraction of the number density (and energy density). We assume a small asymmetric abundance of the C particle whose charge is compensated by a heavy X particle so that the relic abundance of dark matter consists mostly of symmetric X and X-bar , with a small asymmetric component made up of X and C . As the universe cools, it undergoes asymmetric recombination binding the free C s into ( XC ) dark atoms efficiently. Even with a tiny asymmetric component, the presence of C particles catalyzes tight coupling between the heavy dark matter X and the dark photon plasma that can lead to a significant suppression of the matter power spectrum on small scales and lead to some of the strongest bounds on such dark matter theories. We find a viable parameter space where structure formation constraints are satisfied and significant dissipative dynamics can occur in galactic haloes but show a large region is excluded. Our model shows that subdominant components in the dark sector can dramatically affect structure formation.

  6. The Dark Side of Strongly Coupled Theories

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos

    2008-01-01

    We investigate the constraints of dark matter search experiments on the different candidates emerging from the minimal quasi-conformal strong coupling theory with fermions in the adjoint representation. For one candidate, the current limits of CDMS exclude a tiny window of masses around 120 GeV. We...... also investigate under what circumstances the newly proposed candidate composed of a -2 negatively charged particle and a $^4He^{+2}$ can explain the discrepancy between the results of the CDMS and DAMA experiments. We found that this type of dark matter should give negative results in CDMS, while...

  7. On the Efficiency of Grain Alignment in Dark Clouds

    Science.gov (United States)

    Lazarian, A.; Goodman, Alyssa A.; Myers, Philip C.

    1997-11-01

    A quantitative analysis of grain alignment in the filamentary dark cloud L1755 in Ophiuchus is presented. We show that the observed decrease of the polarization-to-extinction ratio for the inner parts of this quiescent dark cloud can be explained as a result of the decrease of the efficiency of grain alignment. We make quantitative estimates of grain alignment efficiency for six mechanisms involving grains with either thermal or suprathermal rotation, interacting with either magnetic field or gaseous flow. We also make semiquantitative estimates of grain alignment by radiative torques. We show that in conditions typical of dark cloud interiors, all known major mechanisms of grain alignment fail. All the studied mechanisms predict polarization at least an order of magnitude below the currently detectable levels of ~1%. On the contrary, in the dark cloud environments where Av sight, including the interiors of dark quiescent clouds, where no alignment is possible. We dedicate this paper to the memory of Edward M. Purcell and Lyman Spitzer, Jr., two pioneers in the quantitative study of the interstellar medium.

  8. Dark matter identification with gamma rays from dwarf galaxies

    International Nuclear Information System (INIS)

    Perelstein, Maxim; Shakya, Bibhushan

    2010-01-01

    If the positron fraction and combined electron-positron flux excesses recently observed by PAMELA, Fermi and HESS are due to dark matter annihilation into lepton-rich final states, the accompanying final state radiation (FSR) photons may be detected by ground-based atmospheric Cherenkov telescopes (ACTs). Satellite dwarf galaxies in the vicinity of the Milky Way are particularly promising targets for this search. We find that current and near-future ACTs have an excellent potential for discovering the FSR photons from dwarfs, although a discovery cannot be guaranteed due to large uncertainties in the fluxes resulting from lack of precise knowledge of dark matter distribution within the dwarfs. We also investigate the possibility of discriminating between different dark matter models based on the measured FSR photon spectrum. For typical parameters, we find that the ACTs can reliably distinguish models predicting dark matter annihilation into two-lepton final states from those favoring four-lepton final states (as in, for example, ''axion portal'' models). In addition, we find that the dark matter particle mass can also be determined from the FSR spectrum

  9. Signature of the interaction between dark energy and dark matter in observations

    International Nuclear Information System (INIS)

    Abdalla, Elcio; Abramo, L. Raul; Souza, Jose C. C. de

    2010-01-01

    We investigate the effect of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. This effect is computed through the Layser-Irvine equation, which describes how an astrophysical system reaches virial equilibrium and was modified to include the dark interactions. Using observational data from almost 100 purportedly relaxed galaxy clusters we put constraints on the strength of the couplings in the dark sector. We compare our results with those from other observations and find that a positive (in the sense of energy flow from dark energy to dark matter) nonvanishing interaction is consistent with the data within several standard deviations.

  10. Dancing in the dark: darkness as a signal in plants.

    Science.gov (United States)

    Seluzicki, Adam; Burko, Yogev; Chory, Joanne

    2017-11-01

    Daily cycles of light and dark provide an organizing principle and temporal constraints under which life on Earth evolved. While light is often the focus of plant studies, it is only half the story. Plants continuously adjust to their surroundings, taking both dawn and dusk as cues to organize their growth, development and metabolism to appropriate times of day. In this review, we examine the effects of darkness on plant physiology and growth. We describe the similarities and differences between seedlings grown in the dark versus those grown in light-dark cycles, and the evolution of etiolated growth. We discuss the integration of the circadian clock into other processes, looking carefully at the points of contact between clock genes and growth-promoting gene-regulatory networks in temporal gating of growth. We also examine daily starch accumulation and degradation, and the possible contribution of dark-specific metabolic controls in regulating energy and growth. Examining these studies together reveals a complex and continuous balancing act, with many signals, dark included, contributing information and guiding the plant through its life cycle. The extraordinary interconnection between light and dark is manifest during cycles of day and night and during seedling emergence above versus below the soil surface. © 2017 John Wiley & Sons Ltd.

  11. Gamma-ray lines from radiative dark matter decay

    International Nuclear Information System (INIS)

    Garny, Mathias; Ibarra, Alejandro; Tran, David; Weniger, Christoph

    2011-01-01

    The decay of dark matter particles which are coupled predominantly to charged leptons has been proposed as a possible origin of excess high-energy positrons and electrons observed by cosmic-ray telescopes PAMELA and Fermi LAT. Even though the dark matter itself is electrically neutral, the tree-level decay of dark matter into charged lepton pairs will generically induce radiative two-body decays of dark matter at the quantum level. Using an effective theory of leptophilic dark matter decay, we calculate the rates of radiative two-body decays for scalar and fermionic dark matter particles. Due to the absence of astrophysical sources of monochromatic gamma rays, the observation of a line in the diffuse gamma-ray spectrum would constitute a strong indication of a particle physics origin of these photons. We estimate the intensity of the gamma-ray line that may be present in the energy range of a few TeV if the dark matter decay interpretation of the leptonic cosmic-ray anomalies is correct and comment on observational prospects of present and future Imaging Cherenkov Telescopes, in particular the CTA

  12. Cosmological anisotropy from non-comoving dark matter and dark energy

    International Nuclear Information System (INIS)

    Harko, Tiberiu; Lobo, Francisco S. N.

    2013-01-01

    We consider a cosmological model in which the two major fluid components of the Universe, dark energy and dark matter, flow with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid, expanding with a four-velocity that is an appropriate combination of the two fluid four-velocities. The energy density of the single cosmological fluid is larger than the sum of the energy densities of the two perfect fluids, i.e., dark energy and dark matter, respectively, and contains a correction term due to the anisotropy generated by the differences in the four-velocities. Furthermore, the gravitational field equations of the two-fluid anisotropic cosmological model are obtained for a Bianchi type I geometry. By assuming that the non-comoving motion of the dark energy and dark matter induces small perturbations in the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker type cosmological background, and that the anisotropy parameter is small, the equations of the cosmological perturbations due to the non-comoving nature of the two major components are obtained. The time evolution of the metric perturbations is explicitly obtained for the cases of the exponential and power law background cosmological expansion. The imprints of a non-comoving dark energy - dark matter on the Cosmic Microwave Background and on the luminosity distance are briefly discussed, and the temperature anisotropies and the quadrupole are explicitly obtained in terms of the metric perturbations of the flat background metric. Therefore, if there is a slight difference between the four-velocities of the dark energy and dark matter, the Universe would acquire some anisotropic characteristics, and its geometry will deviate from the standard FLRW one. In fact, the recent Planck results show that the presence of an intrinsic large scale anisotropy in the Universe cannot be excluded a priori, so that the model presented in this work can be considered as a

  13. Extra Dimensions are Dark: II Fermionic Dark Matter

    OpenAIRE

    Rizzo, Thomas G.

    2018-01-01

    Extra dimensions can be very useful tools when constructing new physics models. Previously, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of bulk dark matter with the brane-localized fields of the Standard Model are mediated by a massive $U(1)_D$ dark photon also living in the bulk. In that setup, where the dark matter was taken to be a complex scalar, a number of nice features were obtained such as $U(1)_D$ breaking b...

  14. Observational constraints on dark matter-dark energy scattering cross section

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Suresh [BITS Pilani, Department of Mathematics, Rajasthan (India); Nunes, Rafael C. [Universidade Federal de Juiz de Fora, Departamento de Fisica, Juiz de Fora, MG (Brazil)

    2017-11-15

    In this letter, we report precise and robust observational constraints on the dark matter-dark energy scattering cross section, using the latest data from cosmic microwave background (CMB) Planck temperature and polarization, baryon acoustic oscillations (BAO) measurements and weak gravitational lensing data from Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). The scattering scenario consists of a pure momentum exchange between the dark components, and we find σ{sub d} < 10{sup -29} cm{sup 2} (m{sub dm}c{sup 2}/GeV) at 95% CL from the joint analysis (CMB + BAO + CFHTLenS), where m{sub dm} is a typical dark matter particle mass. We notice that the scattering among the dark components may influence the growth of large scale structure in the Universe, leaving the background cosmology unaltered. (orig.)

  15. Cosmic history of chameleonic dark matter in F (R ) gravity

    Science.gov (United States)

    Katsuragawa, Taishi; Matsuzaki, Shinya

    2018-03-01

    We study the cosmic history of the scalaron in F (R ) gravity with constructing the time evolution of the cosmic environment and discuss the chameleonic dark matter based on the chameleon mechanism in the early and current Universe. We then find that the scalaron can be a dark matter. We also propose an interesting possibility that the F (R ) gravity can address the coincidence problem.

  16. Large-scale instability in interacting dark energy and dark matter fluids

    International Nuclear Information System (INIS)

    Väliviita, Jussi; Majerotto, Elisabetta; Maartens, Roy

    2008-01-01

    If dark energy interacts with dark matter, this gives a new approach to the coincidence problem. But interacting dark energy models can suffer from pathologies. We consider the case where the dark energy is modelled as a fluid with constant equation of state parameter w. Non-interacting constant-w models are well behaved in the background and in the perturbed universe. But the combination of constant w and a simple interaction with dark matter leads to an instability in the dark sector perturbations at early times: the curvature perturbation blows up on super-Hubble scales. Our results underline how important it is to carefully analyse the relativistic perturbations when considering models of coupled dark energy. The instability that we find has been missed in some previous work where the perturbations were not consistently treated. The unstable mode dominates even if adiabatic initial conditions are used. The instability also arises regardless of how weak the coupling is. This non-adiabatic instability is different from previously discovered adiabatic instabilities on small scales in the strong-coupling regime

  17. Signals of dark matter in a supersymmetric two dark matter model

    International Nuclear Information System (INIS)

    Fukuoka, Hiroki; Suematsu, Daijiro; Toma, Takashi

    2011-01-01

    Supersymmetric radiative neutrino mass models have often two dark matter candidates. One is the usual lightest neutralino with odd R parity and the other is a new neutral particle whose stability is guaranteed by a discrete symmetry that forbids tree-level neutrino Yukawa couplings. If their relic abundance is comparable, dark matter phenomenology can be largely different from the minimal supersymmetric standard model (MSSM). We study this in a supersymmetric radiative neutrino mass model with the conserved R parity and a Z 2 symmetry weakly broken by the anomaly effect. The second dark matter with odd parity of this new Z 2 is metastable and decays to the neutralino dark matter. Charged particles and photons associated to this decay can cause the deviation from the expected background of the cosmic rays. Direct search of the neutralino dark matter is also expected to show different features from the MSSM since the relic abundance is not composed of the neutralino dark matter only. We discuss the nature of dark matter in this model by analyzing these signals quantitatively

  18. Dissipative dark matter and the Andromeda plane of satellites

    International Nuclear Information System (INIS)

    Randall, Lisa; Scholtz, Jakub

    2015-01-01

    We show that dissipative dark matter can potentially explain the large observed mass to light ratio of the dwarf satellite galaxies that have been observed in the recently identified planar structure around Andromeda, which are thought to result from tidal forces during a galaxy merger. Whereas dwarf galaxies created from ordinary disks would be dark matter poor, dark matter inside the galactic plane not only provides a source of dark matter, but one that is more readily bound due to the dark matter's lower velocity. This initial N-body study shows that with a thin disk of dark matter inside the baryonic disk, mass-to-light ratios as high as O(90) can be generated when tidal forces pull out patches of sizes similar to the scales of Toomre instabilities of the dark disk. A full simulation will be needed to confirm this result

  19. Dark coupling

    International Nuclear Information System (INIS)

    Gavela, M.B.; Hernández, D.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

    2009-01-01

    The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ''phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed

  20. Dark matter for excess of AMS-02 positrons and antiprotons

    Directory of Open Access Journals (Sweden)

    Chuan-Hung Chen

    2015-07-01

    Full Text Available We propose a dark matter explanation to simultaneously account for the excess of antiproton-to-proton and positron power spectra observed in the AMS-02 experiment while having the right dark matter relic abundance and satisfying the current direct search bounds. We extend the Higgs triplet model with a hidden gauge symmetry of SU(2X that is broken to Z3 by a quadruplet scalar field, rendering the associated gauge bosons stable weakly-interacting massive particle dark matter candidates. By coupling the complex Higgs triplet and the SU(2X quadruplet, the dark matter candidates can annihilate into triplet Higgs bosons each of which in turn decays into lepton or gauge boson final states. Such a mechanism gives rise to correct excess of positrons and antiprotons with an appropriate choice of the triplet vacuum expectation value. Besides, the model provides a link between neutrino mass and dark matter phenomenology.

  1. Twin Higgs Asymmetric Dark Matter.

    Science.gov (United States)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-18

    We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20  GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.

  2. Cross-correlating CMB temperature fluctuations with high-energy γ-ray from Dark-Matter annihilation

    International Nuclear Information System (INIS)

    Pieri, L.

    2013-01-01

    In this paper we compute the Integrated Sachs-Wolfe effect due to the presence of dark-matter structures on cosmological scale. We cross-correlate the CMB temperature fluctuations with the extragalactic high-energy γ-ray flux map obtained with FERMI-LAT. We find a null signal consistent with the theory and conclude that the presence of halos and subhalos at galactic and extragalactic scale, if not excluded, will be hardly discoverable.

  3. Dark Matter

    International Nuclear Information System (INIS)

    Holt, S. S.; Bennett, C. L.

    1995-01-01

    These proceedings represent papers presented at the Astrophysics conference in Maryland, organized by NASA Goddard Space Flight Center and the University of Maryland. The topics covered included low mass stars as dark matter, dark matter in galaxies and clusters, cosmic microwave background anisotropy, cold and hot dark matter, and the large scale distribution and motions of galaxies. There were eighty five papers presented. Out of these, 10 have been abstracted for the Energy Science and Technology database

  4. Testing for Dark Matter Trapped in the Solar System

    Science.gov (United States)

    Krisher, Timothy P.

    1996-01-01

    We consider the possibility of dark matter trapped in the solar system in bound solar orbits. If there exist mechanisms for dissipating excess kinetic energy by an amount sufficient for generating bound solar orbits, then trapping of galactic dark matter might have taken place during formation of the solar system, or could be an ongoing process. Possible locations for acumulation of trapped dark matter are orbital resonances with the planets or regions in the outer solar system. It is posible to test for the presence of unseen matter by detecting its gravitational effects. Current results for dynamical limits obtained from analyses of planetary ephemeris data and spacecraft tracking data are presented. Possible future improvements are discussed.

  5. Strategies for dark matter detection

    International Nuclear Information System (INIS)

    Silk, J.

    1988-01-01

    The present status of alternative forms of dark matter, both baryonic and nonbaryonic, is reviewed. Alternative arguments are presented for the predominance of either cold dark matter (CDM) or of baryonic dark matter (BDM). Strategies are described for dark matter detection, both for dark matter that consists of weakly interacting relic particles and for dark matter that consists of dark stellar remnants

  6. Importance of supernovae at z>1.5 to probe dark energy

    International Nuclear Information System (INIS)

    Linder, Eric V.; Huterer, Dragan

    2003-01-01

    The accelerating expansion of the universe suggests that an unknown component with strongly negative pressure, called dark energy, currently dominates the dynamics of the universe. Such a component makes up ∼70% of the energy density of the universe yet has not been predicted by the standard model of particle physics. The best method for exploring the nature of this dark energy is to map the recent expansion history, at which type Ia supernovae have proved adept. We examine here the depth of survey necessary to provide a precise and qualitatively complete description of dark energy. A realistic analysis of parameter degeneracies, allowance for natural time variation of the dark energy equation of state, and systematic errors in astrophysical observations all demonstrate the importance of a survey covering the full range 0< z < or approx. 2 for revealing the nature of dark energy

  7. Future cosmological sensitivity for hot dark matter axions

    CERN Document Server

    Archidiacono, Maria; Hamann, Jan; Hannestad, Steen; Raffelt, Georg; Wong, Yvonne Y Y

    2015-01-01

    We study the potential of a future, large-volume photometric survey to constrain the axion mass $m_a$ in the hot dark matter limit. Future surveys such as Euclid will have significantly more constraining power than current observations for hot dark matter. Nonetheless, the lowest accessible axion masses are limited by the fact that axions lighter than $\\sim 0.15$ eV decouple before the QCD epoch, assumed here to occur at a temperature $T_{\\rm QCD} \\sim 170$ MeV; this leaves an axion population of such low density that its late-time cosmological impact is negligible. For larger axion masses, $m_a \\gtrsim 0.15$ eV, where axions remain in equilibrium until after the QCD phase transition, we find that a Euclid-like survey combined with Planck CMB data can detect $m_a$ at very high significance. Our conclusions are robust against assumptions about prior knowledge of the neutrino mass. Given that the proposed IAXO solar axion search is sensitive to $m_a\\lesssim 0.2$ eV, the axion mass range probed by cosmology is n...

  8. Sterile neutrino portal to Dark Matter I: the U(1)B−L case

    International Nuclear Information System (INIS)

    Escudero, Miguel; Rius, Nuria; Sanz, Verónica

    2017-01-01

    In this paper we explore the possibility that the sterile neutrino and Dark Matter sectors in the Universe have a common origin. We study the consequences of this assumption in the simple case of coupling the dark sector to the Standard Model via a global U(1) B−L , broken down spontaneously by a dark scalar. This dark scalar provides masses to the dark fermions and communicates with the Higgs via a Higgs portal coupling. We find an interesting interplay between Dark Matter annihilation to dark scalars — the CP-even that mixes with the Higgs and the CP-odd which becomes a Goldstone boson, the Majoron — and heavy neutrinos, as well as collider probes via the coupling to the Higgs. Moreover, Dark Matter annihilation into sterile neutrinos and its subsequent decay to gauge bosons and quarks, charged leptons or neutrinos lead to indirect detection signatures which are close to current bounds on the gamma ray flux from the galactic center and dwarf galaxies.

  9. Exothermic dark matter

    International Nuclear Information System (INIS)

    Graham, Peter W.; Saraswat, Prashant; Harnik, Roni; Rajendran, Surjeet

    2010-01-01

    We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass ∼few GeV and splittings ∼5 keV. It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state. In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.

  10. Hybrid Dark Matter

    OpenAIRE

    Chao, Wei

    2018-01-01

    Dark matter can be produced in the early universe via the freeze-in or freeze-out mechanisms. Both scenarios were investigated in references, but the production of dark matters via the combination of these two mechanisms are not addressed. In this paper we propose a hybrid dark matter model where dark matters have two components with one component produced thermally and the other one produced non-thermally. We present for the first time the analytical calculation for the relic abundance of th...

  11. Baryonic pinching of galactic dark matter halos

    International Nuclear Information System (INIS)

    Gustafsson, Michael; Fairbairn, Malcolm; Sommer-Larsen, Jesper

    2006-01-01

    High resolution cosmological N-body simulations of four galaxy-scale dark matter halos are compared to corresponding N-body/hydrodynamical simulations containing dark matter, stars and gas. The simulations without baryons share features with others described in the literature in that the dark matter density slope continuously decreases towards the center, with a density ρ DM ∝r -1.3±0.2 , at about 1% of the virial radius for our Milky Way sized galaxies. The central cusps in the simulations which also contain baryons steepen significantly, to ρ DM ∝r -1.9±0.2 , with an indication of the inner logarithmic slope converging. Models of adiabatic contraction of dark matter halos due to the central buildup of stellar/gaseous galaxies are examined. The simplest and most commonly used model, by Blumenthal et al., is shown to overestimate the central dark matter density considerably. A modified model proposed by Gnedin et al. is tested and it is shown that, while it is a considerable improvement, it is not perfect. Moreover, it is found that the contraction parameters in their model not only depend on the orbital structure of the dark-matter-only halos but also on the stellar feedback prescription which is most relevant for the baryonic distribution. Implications for dark matter annihilation at the galactic center are discussed and it is found that, although our simulations show a considerable reduced dark matter halo contraction as compared to the Blumenthal et al. model, the fluxes from dark matter annihilation are still expected to be enhanced by at least a factor of a hundred, as compared to dark-matter-only halos. Finally, it is shown that, while dark-matter-only halos are typically prolate, the dark matter halos containing baryons are mildly oblate with minor-to-major axis ratios of c/a=0.73±0.11, with their flattening aligned with the central baryonic disks

  12. Structure formation in inhomogeneous Early Dark Energy models

    International Nuclear Information System (INIS)

    Batista, R.C.; Pace, F.

    2013-01-01

    We study the impact of Early Dark Energy fluctuations in the linear and non-linear regimes of structure formation. In these models the energy density of dark energy is non-negligible at high redshifts and the fluctuations in the dark energy component can have the same order of magnitude of dark matter fluctuations. Since two basic approximations usually taken in the standard scenario of quintessence models, that both dark energy density during the matter dominated period and dark energy fluctuations on small scales are negligible, are not valid in such models, we first study approximate analytical solutions for dark matter and dark energy perturbations in the linear regime. This study is helpful to find consistent initial conditions for the system of equations and to analytically understand the effects of Early Dark Energy and its fluctuations, which are also verified numerically. In the linear regime we compute the matter growth and variation of the gravitational potential associated with the Integrated Sachs-Wolf effect, showing that these observables present important modifications due to Early Dark Energy fluctuations, though making them more similar to the ΛCDM model. We also make use of the Spherical Collapse model to study the influence of Early Dark Energy fluctuations in the nonlinear regime of structure formation, especially on δ c parameter, and their contribution to the halo mass, which we show can be of the order of 10%. We finally compute how the number density of halos is modified in comparison to the ΛCDM model and address the problem of how to correct the mass function in order to take into account the contribution of clustered dark energy. We conclude that the inhomogeneous Early Dark Energy models are more similar to the ΛCDM model than its homogeneous counterparts

  13. Holographic dark energy interacting with dark matter in a closed Universe

    International Nuclear Information System (INIS)

    Cruz, Norman; Lepe, Samuel; Pena, Francisco; Saavedra, Joel

    2008-01-01

    A cosmological model of an holographic dark energy interacting with dark matter throughout a decaying term of the form Q=3(λ 1 ρ DE +λ 2 ρ m )H is investigated. General constraint on the parameters of the model are found when accelerated expansion is imposed and we found a phantom scenario, without any reference to a specific equation of state for the dark energy. The behavior of equation of state for dark energy is also discussed

  14. Concentrated dark matter: Enhanced small-scale structure from codecaying dark matter

    OpenAIRE

    Dror, Jeff A.; Kuflik, Eric; Melcher, Brandon; Watson, Scott

    2018-01-01

    We study the cosmological consequences of codecaying dark matter—a recently proposed mechanism for depleting the density of dark matter through the decay of nearly degenerate particles. A generic prediction of this framework is an early dark matter dominated phase in the history of the Universe, that results in the enhanced growth of dark matter perturbations on small scales. We compute the duration of the early matter dominated phase and show that the perturbations are robust against washout...

  15. Secretly asymmetric dark matter

    Science.gov (United States)

    Agrawal, Prateek; Kilic, Can; Swaminathan, Sivaramakrishnan; Trendafilova, Cynthia

    2017-01-01

    We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early Universe, even though the total dark matter number remains zero throughout the history of the Universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal weakly interacting massive particles. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.

  16. High current plasma electron emitter

    International Nuclear Information System (INIS)

    Fiksel, G.; Almagri, A.F.; Craig, D.

    1995-07-01

    A high current plasma electron emitter based on a miniature plasma source has been developed. The emitting plasma is created by a pulsed high current gas discharge. The electron emission current is 1 kA at 300 V at the pulse duration of 10 ms. The prototype injector described in this paper will be used for a 20 kA electrostatic current injection experiment in the Madison Symmetric Torus (MST) reversed-field pinch. The source will be replicated in order to attain this total current requirement. The source has a simple design and has proven very reliable in operation. A high emission current, small size (3.7 cm in diameter), and low impurity generation make the source suitable for a variety of fusion and technological applications

  17. Dark energy and dark matter perturbations in singular universes

    International Nuclear Information System (INIS)

    Denkiewicz, Tomasz

    2015-01-01

    We discuss the evolution of density perturbations of dark matter and dark energy in cosmological models which admit future singularities in a finite time. Up to now geometrical tests of the evolution of the universe do not differentiate between singular universes and ΛCDM scenario. We solve perturbation equations using the gauge invariant formalism. The analysis shows that the detailed reconstruction of the evolution of perturbations within singular cosmologies, in the dark sector, can exhibit important differences between the singular universes models and the ΛCDM cosmology. This is encouraging for further examination and gives hope for discriminating between those models with future galaxy weak lensing experiments like the Dark Energy Survey (DES) and Euclid or CMB observations like PRISM and CoRE

  18. Dark energy and equivalence principle constraints from astrophysical tests of the stability of the fine-structure constant

    Energy Technology Data Exchange (ETDEWEB)

    Martins, C.J.A.P.; Pinho, A.M.M.; Alves, R.F.C. [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Pino, M. [Institut Domènech i Montaner, C/Maspujols 21-23, 43206 Reus (Spain); Rocha, C.I.S.A. [Externato Ribadouro, Rua de Santa Catarina 1346, 4000-447 Porto (Portugal); Wietersheim, M. von, E-mail: Carlos.Martins@astro.up.pt, E-mail: Ana.Pinho@astro.up.pt, E-mail: up201106579@fc.up.pt, E-mail: mpc_97@yahoo.com, E-mail: cisar97@hotmail.com, E-mail: maxivonw@gmail.com [Institut Manuel Sales i Ferré, Avinguda de les Escoles 6, 43550 Ulldecona (Spain)

    2015-08-01

    Astrophysical tests of the stability of fundamental couplings, such as the fine-structure constant α, are becoming an increasingly powerful probe of new physics. Here we discuss how these measurements, combined with local atomic clock tests and Type Ia supernova and Hubble parameter data, constrain the simplest class of dynamical dark energy models where the same degree of freedom is assumed to provide both the dark energy and (through a dimensionless coupling, ζ, to the electromagnetic sector) the α variation. Specifically, current data tightly constrains a combination of ζ and the present dark energy equation of state w{sub 0}. Moreover, in these models the new degree of freedom inevitably couples to nucleons (through the α dependence of their masses) and leads to violations of the Weak Equivalence Principle. We obtain indirect bounds on the Eötvös parameter η that are typically stronger than the current direct ones. We discuss the model-dependence of our results and briefly comment on how the forthcoming generation of high-resolution ultra-stable spectrographs will enable significantly tighter constraints.

  19. Dark energy and equivalence principle constraints from astrophysical tests of the stability of the fine-structure constant

    International Nuclear Information System (INIS)

    Martins, C.J.A.P.; Pinho, A.M.M.; Alves, R.F.C.; Pino, M.; Rocha, C.I.S.A.; Wietersheim, M. von

    2015-01-01

    Astrophysical tests of the stability of fundamental couplings, such as the fine-structure constant α, are becoming an increasingly powerful probe of new physics. Here we discuss how these measurements, combined with local atomic clock tests and Type Ia supernova and Hubble parameter data, constrain the simplest class of dynamical dark energy models where the same degree of freedom is assumed to provide both the dark energy and (through a dimensionless coupling, ζ, to the electromagnetic sector) the α variation. Specifically, current data tightly constrains a combination of ζ and the present dark energy equation of state w 0 . Moreover, in these models the new degree of freedom inevitably couples to nucleons (through the α dependence of their masses) and leads to violations of the Weak Equivalence Principle. We obtain indirect bounds on the Eötvös parameter η that are typically stronger than the current direct ones. We discuss the model-dependence of our results and briefly comment on how the forthcoming generation of high-resolution ultra-stable spectrographs will enable significantly tighter constraints

  20. Dark states in spin-polarized transport through triple quantum dot molecules

    Science.gov (United States)

    Wrześniewski, K.; Weymann, I.

    2018-02-01

    We study the spin-polarized transport through a triple-quantum-dot molecule weakly coupled to ferromagnetic leads. The analysis is performed by means of the real-time diagrammatic technique, including up to the second order of perturbation expansion with respect to the tunnel coupling. The emphasis is put on the impact of dark states on spin-resolved transport characteristics. It is shown that the interplay of coherent population trapping and cotunneling processes results in a highly nontrivial behavior of the tunnel magnetoresistance, which can take negative values. Moreover, a super-Poissonian shot noise is found in transport regimes where the current is blocked by the formation of dark states, which can be additionally enhanced by spin dependence of tunneling processes, depending on the magnetic configuration of the device. The mechanisms leading to those effects are thoroughly discussed.

  1. Hidden charged dark matter

    International Nuclear Information System (INIS)

    Feng, Jonathan L.; Kaplinghat, Manoj; Tu, Huitzu; Yu, Hai-Bo

    2009-01-01

    Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact (\\rm U)(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many novel properties not shared by neutral dark matter: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may reduce its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially impacting properties of the Bullet Cluster and the observed morphology of galactic halos. We analyze all of these effects in a WIMPless model in which the hidden sector is a simplified version of the minimal supersymmetric standard model and the dark matter is a hidden sector stau. We find that charged hidden dark matter is viable and consistent with the correct relic density for reasonable model parameters and dark matter masses in the range 1 GeV ∼ X ∼< 10 TeV. At the same time, in the preferred range of parameters, this model predicts cores in the dark matter halos of small galaxies and other halo properties that may be within the reach of future observations. These models therefore provide a viable and well-motivated framework for collisional dark matter with Sommerfeld enhancement, with novel implications for astrophysics and dark matter searches

  2. The DarkStars code: a publicly available dark stellar evolution package

    CERN Document Server

    Scott, Pat; Fairbairn, Malcolm

    2009-01-01

    We announce the public release of the 'dark' stellar evolution code DarkStars. The code simultaneously solves the equations of WIMP capture and annihilation in a star with those of stellar evolution assuming approximate hydrostatic equilibrium. DarkStars includes the most extensive WIMP microphysics of any dark evolution code to date. The code employs detailed treatments of the capture process from a range of WIMP velocity distributions, as well as composite WIMP distribution and conductive energy transport schemes based on the WIMP mean-free path in the star. We give a brief description of the input physics and practical usage of the code, as well as examples of its application to dark stars at the Galactic centre.

  3. Constraining the interaction between dark sectors with future HI intensity mapping observations

    Science.gov (United States)

    Xu, Xiaodong; Ma, Yin-Zhe; Weltman, Amanda

    2018-04-01

    We study a model of interacting dark matter and dark energy, in which the two components are coupled. We calculate the predictions for the 21-cm intensity mapping power spectra, and forecast the detectability with future single-dish intensity mapping surveys (BINGO, FAST and SKA-I). Since dark energy is turned on at z ˜1 , which falls into the sensitivity range of these radio surveys, the HI intensity mapping technique is an efficient tool to constrain the interaction. By comparing with current constraints on dark sector interactions, we find that future radio surveys will produce tight and reliable constraints on the coupling parameters.

  4. Recent Developments in Supersymmetric and Hidden Sector Dark Matter

    International Nuclear Information System (INIS)

    Feldman, Daniel; Liu Zuowei; Nath, Pran

    2008-01-01

    New results which correlate SUSY dark matter with LHC signals are presented, and a brief review of recent developments in supersymmetric and hidden sector dark matter is given. It is shown that the direct detection of dark matter is very sensitive to the hierarchical SUSY sparticle spectrum and the spectrum is very useful in distinguishing models. It is shown that the prospects of the discovery of neutralino dark matter are very bright on the 'Chargino Wall' due to a copious number of model points on the Wall, where the NLSP is the Chargino, and the spin independent neutralino-proton cross section is maintained at high values in the 10 -44 cm 2 range for neutralino masses up to ∼850 GeV. It is also shown that the direct detection of dark matter along with lepton plus jet signatures and missing energy provide dual, and often complementary, probes of supersymmetry. Finally, we discuss an out of the box possibility for dark matter, which includes dark matter from the hidden sector, which could either consist of extra weakly interacting dark matter (a Stino XWIMP), or milli-charged dark matter arising from the Stueckelberg extensions of the MSSM or the SM.

  5. Detecting dark matter with imploding pulsars in the galactic center.

    Science.gov (United States)

    Bramante, Joseph; Linden, Tim

    2014-11-07

    The paucity of old millisecond pulsars observed at the galactic center of the Milky Way could be the result of dark matter accumulating in and destroying neutron stars. In regions of high dark matter density, dark matter clumped in a pulsar can exceed the Schwarzschild limit and collapse into a natal black hole which destroys the pulsar. We examine what dark matter models are consistent with this hypothesis and find regions of parameter space where dark matter accumulation can significantly degrade the neutron star population within the galactic center while remaining consistent with observations of old millisecond pulsars in globular clusters and near the solar position. We identify what dark matter couplings and masses might cause a young pulsar at the galactic center to unexpectedly extinguish. Finally, we find that pulsar collapse age scales inversely with the dark matter density and linearly with the dark matter velocity dispersion. This implies that maximum pulsar age is spatially dependent on position within the dark matter halo of the Milky Way. In turn, this pulsar age spatial dependence will be dark matter model dependent.

  6. Very heavy dark Skyrmions

    International Nuclear Information System (INIS)

    Dick, Rainer

    2017-01-01

    A dark sector with a solitonic component provides a means to circumvent the problem of generically low annihilation cross sections of very heavy dark matter particles. At the same time, enhanced annihilation cross sections are necessary for indirect detection of very heavy dark matter components beyond 100 TeV. Non-thermally produced dark matter in this mass range could therefore contribute to the cosmic γ-ray and neutrino flux above 100 TeV, and massive Skyrmions provide an interesting framework for the discussion of these scenarios. Therefore a Higgs portal and a neutrino portal for very heavy Skyrmion dark matter are discussed. The Higgs portal model demonstrates a dark mediator bottleneck, where limitations on particle annihilation cross sections will prevent a signal from the potentially large soliton annihilation cross sections. This problem can be avoided in models where the dark mediator decays. This is illustrated by the neutrino portal for Skyrmion dark matter. (orig.)

  7. Collapsed Dark Matter Structures

    Science.gov (United States)

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-02-01

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  8. Collapsed Dark Matter Structures.

    Science.gov (United States)

    Buckley, Matthew R; DiFranzo, Anthony

    2018-02-02

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  9. Very heavy dark Skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Dick, Rainer [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, SK (Canada)

    2017-12-15

    A dark sector with a solitonic component provides a means to circumvent the problem of generically low annihilation cross sections of very heavy dark matter particles. At the same time, enhanced annihilation cross sections are necessary for indirect detection of very heavy dark matter components beyond 100 TeV. Non-thermally produced dark matter in this mass range could therefore contribute to the cosmic γ-ray and neutrino flux above 100 TeV, and massive Skyrmions provide an interesting framework for the discussion of these scenarios. Therefore a Higgs portal and a neutrino portal for very heavy Skyrmion dark matter are discussed. The Higgs portal model demonstrates a dark mediator bottleneck, where limitations on particle annihilation cross sections will prevent a signal from the potentially large soliton annihilation cross sections. This problem can be avoided in models where the dark mediator decays. This is illustrated by the neutrino portal for Skyrmion dark matter. (orig.)

  10. Chaplygin dark star

    International Nuclear Information System (INIS)

    Bertolami, O.; Paramos, J.

    2005-01-01

    We study the general properties of a spherically symmetric body described through the generalized Chaplygin equation of state. We conclude that such an object, dubbed generalized Chaplygin dark star, should exist within the context of the generalized Chaplygin gas (GCG) model of unification of dark energy and dark matter, and derive expressions for its size and expansion velocity. A criteria for the survival of the perturbations in the GCG background that give origin to the dark star are developed, and its main features are analyzed

  11. Dark Matter Mystery Deepens in Cosmic "Train Wreck"

    Science.gov (United States)

    2007-08-01

    Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior. "These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even reexamine the nature of dark matter itself." There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects. Illustration of Abell 520 System Illustration of Abell 520 System Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas. A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies. "It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves." Animation of Galaxy Cluster Animation of Galaxy Cluster In addition to the dark matter core, a

  12. Geodesics of black holes with dark energy

    Science.gov (United States)

    Ghaderi, K.

    2017-12-01

    Dark energy is the most popular hypothesis to explain recent observations suggesting that the world will increasingly expand. One of the models of dark energy is quintessence which is highly plausible. In this paper, we investigate the effect of dark energy on the null geodesics of Schwarzschild, Reissner-Nordström, Schwarzschild-de Sitter and Bardeen black holes. Using the definition of effective potential, the radius of the circular orbits, the period, the instability of the circular orbits, the force exerted on the photons and the deviation angle of light in quintessence field are calculated and the results are analyzed and discussed.

  13. Holographic dark energy interacting with dark matter in a closed Universe

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile); Lepe, Samuel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de La Frontera, Avda. Francisco Salazar 01145, Casilla 54-D Temuco (Chile); Saavedra, Joel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile)], E-mail: joel.saavedra@ucv.cl

    2008-11-27

    A cosmological model of an holographic dark energy interacting with dark matter throughout a decaying term of the form Q=3({lambda}{sub 1}{rho}{sub DE}+{lambda}{sub 2}{rho}{sub m})H is investigated. General constraint on the parameters of the model are found when accelerated expansion is imposed and we found a phantom scenario, without any reference to a specific equation of state for the dark energy. The behavior of equation of state for dark energy is also discussed.

  14. Modified holographic Ricci dark energy coupled to interacting dark matter and a non-interacting baryonic component

    Energy Technology Data Exchange (ETDEWEB)

    Chimento, Luis P.; Richarte, Martin G. [Universidad de Buenos Aires, IFIBA, CONICET, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Forte, Monica [Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2013-01-15

    We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component. The estimations of the cosmic parameters with Hubble data lead to an age of the universe of 13.17 Gyr and show that the MHRDE is free from the cosmic-age problem at low redshift (0{<=}z{<=}2) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non-interacting baryonic matter forces that the amount of dark energy at z{sub t} {proportional_to} O(1) changes abruptly implying that {Omega} {sub x} (z {approx_equal}1100)=0.03, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also find that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of {Omega} {sub x} at the big bang nucleosynthesis era does not disturb the observed helium abundance in the universe provided that the bound {Omega} {sub x} (z {approx_equal}10 {sup 10}) <0.21 is hold. (orig.)

  15. arXiv Signatures of Dark Radiation in Neutrino and Dark Matter Detectors

    CERN Document Server

    Cui, Yanou; Pradler, Josef

    2018-05-03

    We consider the generic possibility that the Universe’s energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In pa...

  16. Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (2/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

  17. Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (3/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

  18. Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (1/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

  19. arXiv Signatures of Dark Radiation in Neutrino and Dark Matter Detectors

    CERN Document Server

    Cui, Yanou; Pradler, Josef

    We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with non-gravitational interactions with Standard Model (SM) particles. Such dark radiation may consist of SM singlets or a non-thermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In pa...

  20. Interacting warm dark matter

    International Nuclear Information System (INIS)

    Cruz, Norman; Palma, Guillermo; Zambrano, David; Avelino, Arturo

    2013-01-01

    We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ m α ρ e β form, where ρ m and ρ e are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ,α,β) as well as w m and w e of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ,α,β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used