WorldWideScience

Sample records for t1-weighted-space dark blood

  1. Kiss High Blood Pressure Goodbye: The Relationship between Dark Chocolate and Hypertension

    Science.gov (United States)

    Nordmoe, Eric D.

    2008-01-01

    This article reports on a delicious finding from a recent study claiming a causal link between dark chocolate consumption and blood pressure reductions. In the article, I provide ideas for using this study to whet student appetites for a discussion of statistical ideas, including experimental design, measurement error and inference methods.

  2. Investigation of the effects of constant darkness and light on blood ...

    African Journals Online (AJOL)

    This study was designed to investigate the effects of constant darkness and light on changes of serum cholesterol, insulin and glucose levels in healthy male rats. In this study, healthy male rats (n = 30) were divided into 3 groups of tens and kept at various light/dark conditions: Control 12:12 light/dark (LD); constant ...

  3. Quantitative retinal and choroidal blood flow during light, dark adaptation and flicker light stimulation in rats using fluorescent microspheres.

    Science.gov (United States)

    Shih, Yen-Yu I; Wang, Lin; De La Garza, Bryan H; Li, Guang; Cull, Grant; Kiel, Jeffery W; Duong, Timothy Q

    2013-02-01

    The present study aimed to quantify retinal and choroidal blood flow (BF) during light, dark adaptation and flicker light stimulation using the microsphere technique. Adult male Sprague-Dawley rats were anesthetized with isoflurane. Eyes were dark (Group I, n = 8), light (Group II, n = 8) adapted or stimulated with 10 Hz flicker light (Group III, n = 10). Retinal and choroidal BF were measured by a previously established method, using a mixture of 8 µm yellow-green and 10 µm red fluorescent microspheres. The microspheres were counted ex vivo in the dissected retina and choroid and in the reference arterial blood under a fluorescent microscope. The choroidal BF was 64.8 ± 29 µl/min (mean ± SD) during dark adaptation, not significantly different from that during light adaptation (66.0 ± 17.8 µl/min). The retinal BF was 13.5 ± 3.2 µl/min during 10 Hz flickering light stimulation, significantly higher than that during dark adaptation in the control fellow eyes (9.9 ± 2.9 µl/min). The choroidal BF values were not statistically different between flicker stimulation and dark adaptation. Retinal BF was 11.6 ± 2.9 µl/min during light adaptation. Dark adaptation did not increase retinal BF (Group I, 8.2 ± 2.4 µl/min; Group II, 9.9 ± 2.9 µl/min). These findings argue against a dark-induced or flicker-induced functional hyperemia in the choroid as a result of the demands of the outer retina. Retinal BF was not higher during dark adaptation. Our data support the conclusion that the inner retina has a higher energy demand in flicker conditions relative to dark.

  4. Cardiac MRI. T2-mapping versus T2-weighted dark-blood TSE imaging for myocardial edema visualization in acute myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Nassenstein, K.; Nensa, F.; Schlosser, T.; Umutlu, L.; Lauenstein, T. [University Hospital Essen (Germany). Dept. of Diagnostic and Interventional Radiology and Neuroradiology; Bruder, O. [Elisabeth Hospital, Essen (Germany). Dept. of Cardiology and Angiology; Maderwald, S.; Ladd, M.E. [Duisburg-Essen Univ., Essen (Germany). Erwin L. Hahn Institute for Magnetic Resonance Imaging

    2014-02-15

    Purpose: To assess the diagnostic accuracy of T2 mapping for the detection of myocardial edema in acute myocardial infarction (AMI), and to compare this diagnostic accuracy with that of the current standard for myocardial edema imaging, which is T2w dark-blood TSE imaging. Materials and Methods: 29 patients with AMI were examined at 1.5 T. For the visualization of myocardial edema, T2 maps, calculated from three T2w SSFP images, and T2w dark-blood TSE images were acquired in standard short- and long-axis views. Cine SSFP images were acquired for the analysis of left ventricular (LV) function and late gadolinium enhancement images (LGE) for the visualization of myocardial necrosis. The T2 maps as well as the T2w dark-blood TSE images were evaluated twice independently from the cine SSFP and LGE images. The presence or absence of myocardial edema was rated visually for each LV segment. As the standard of reference, the infarct zone was defined based on the cine SSFP and the LGE images. Results: In this segment-based analysis, T2 mapping showed a sensitivity of 82 % and a specificity of 94 % for the detection of edema in the infarct zone. T2w dark-blood TSE imaging revealed a sensitivity of 50 % and a specificity of 98 %. T2 mapping showed a higher intra-rater agreement compared to T2w dark-blood TSE imaging ({kappa}: 0.87 vs. 0.76). Conclusions: T2 mapping allows for the visualization of myocardial edema in AMI with a high sensitivity and specificity, and features better diagnostic accuracy in terms of a higher sensitivity compared to T2w dark-blood TSE imaging. (orig.)

  5. River of Blood: George Martin’s Fevre Dream and the road to dark designr

    Directory of Open Access Journals (Sweden)

    Andrew Howe

    2017-01-01

    Full Text Available http://dx.doi.org/10.5007/2175-8026.2017v70n1p81 With his publication of Fevre Dream in 1982, George R. R. Martin tried his hand at the “sympathetic vampire” tale, one popularized just a few years previously by Anne Rice.  A tale of vampires haunting the American South during the lead up to the Civil War, Fevre Dream focused upon moral ambiguity, the brutality of power, and other narrative aspects that would eventually emerge more fully developed in the author’s magnum opus, the acclaimed A Song of Ice and Fire series.  Largely forgotten, Fevre Dream is important in that a close reading of the text indicates Martin’s embrace of dark fantasy, not only in the bleak thematic material but also in the embrace of real-world historical events (the American Civil War and institutions (slavery.

  6. Dark blood versus bright blood T2* acquisition in cardiovascular magnetic resonance (CMR) for thalassaemia major (TM) patients: Evaluation of feasibility, reproducibility and image quality

    International Nuclear Information System (INIS)

    Liguori, Carlo; Di Giampietro, Ilenia; Pitocco, Francesca; De Vivo, Aldo Eros; Schena, Emiliano; Mortato, Luca; Pirro, Federica; Cianciulli, Paolo; Zobel, Bruno Beomonte

    2014-01-01

    Objectives: To compare the effectiveness of dark blood (DB) versus bright blood (BB) sequences. To assess the intra and inter-observer variability and inter-study reproducibility between BB versus DB. To evaluate image quality level in the two sequences. Methods: In a setting of 138 patients we performed CMR using cardiac gated Gradient-multiecho single breath-hold BB and DB sequences in the middle ventricular septum. Each acquisition was repeated during the same exam. Truncation method was used to account for background noise. Image quality (IQ) was assessed using a 5 point grading scale and image analysis was conducted by 2 experienced observers. Results: Compared with the conventional BB acquisition, the coefficient of correlation and significance of the DB technique was superior for intra-observer reproducibility (p < 0.001), inter-observer reproducibility (p < 0.001) and inter-study reproducibility (p < 0.001). The variability is also lower for DB sequences for T2* values <14 ms. Assessment of artifacts showed a superior score for DB versus BB scans (4 versus 3, p < 0.001). Conclusions: Improvement in terms of inter observer and inter study variability using DB sequences was obtained. The greatest disparity between them was seen in inter-study reproducibility and higher IQ in DB was seen. Study demonstrates better performance of DB imaging compared to BB in presence of comparable effectiveness

  7. Dark blood versus bright blood T2* acquisition in cardiovascular magnetic resonance (CMR) for thalassaemia major (TM) patients: Evaluation of feasibility, reproducibility and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Liguori, Carlo, E-mail: c.liguori@unicampus.it [Department of Diagnostic Imaging, Campus Bio Medico University, via Alvaro del Portillo 200, 00128 Rome (Italy); Di Giampietro, Ilenia; Pitocco, Francesca; De Vivo, Aldo Eros [Department of Diagnostic Imaging, Campus Bio Medico University, via Alvaro del Portillo 200, 00128 Rome (Italy); Schena, Emiliano [Unit of Measurements and Biomedical Instrumentation, Campus Bio Medico University, via Alvaro del Portillo 200, 00128 Rome (Italy); Mortato, Luca [Department of Diagnostic Imaging, Campus Bio Medico University, via Alvaro del Portillo 200, 00128 Rome (Italy); Pirro, Federica [Department of Biomaging and Radiological Sciences, Catholic University of Sacred Herart, Largo A. Gemelli 1, 00135 Rome (Italy); Cianciulli, Paolo [Thalassemia Unit, Ospedale Sant Eugenio, Piazzale dell’Umanesimo 10, 00143 Rome (Italy); Zobel, Bruno Beomonte [Department of Diagnostic Imaging, Campus Bio Medico University, via Alvaro del Portillo 200, 00128 Rome (Italy)

    2014-01-15

    Objectives: To compare the effectiveness of dark blood (DB) versus bright blood (BB) sequences. To assess the intra and inter-observer variability and inter-study reproducibility between BB versus DB. To evaluate image quality level in the two sequences. Methods: In a setting of 138 patients we performed CMR using cardiac gated Gradient-multiecho single breath-hold BB and DB sequences in the middle ventricular septum. Each acquisition was repeated during the same exam. Truncation method was used to account for background noise. Image quality (IQ) was assessed using a 5 point grading scale and image analysis was conducted by 2 experienced observers. Results: Compared with the conventional BB acquisition, the coefficient of correlation and significance of the DB technique was superior for intra-observer reproducibility (p < 0.001), inter-observer reproducibility (p < 0.001) and inter-study reproducibility (p < 0.001). The variability is also lower for DB sequences for T2* values <14 ms. Assessment of artifacts showed a superior score for DB versus BB scans (4 versus 3, p < 0.001). Conclusions: Improvement in terms of inter observer and inter study variability using DB sequences was obtained. The greatest disparity between them was seen in inter-study reproducibility and higher IQ in DB was seen. Study demonstrates better performance of DB imaging compared to BB in presence of comparable effectiveness.

  8. The Influence of the Arabian Nights on Modern Young Adult Literature: Midwinter Blood and in Darkness as Examples

    Directory of Open Access Journals (Sweden)

    Brahim Bouali

    2015-11-01

    personal opinion and consider the whole Arabian nights as a multi-dimensional genre or better canon genre from which artists continue to be inspired. The novelty in this study may be summarized in two points. First, it attempts to consider One Thousand and a Night as a canon genre that in a way proves the limitation of classical genre categorization/nomenclature and pushes us to introduce new terms in genre theory such as the notion of the canon genre and even the concept of anti-genre[4]which will be dealt furtively in this paper. Second, it attempts to study its degree of influence on modern young adult literature represented by Midwinter Blood and in Darkness both Winners, successively, of the 2013 and 2014 Michael L. Printz awards. If we question/deconstruct the discourse in the Foucauldian sense in order to find the absence that is hidden by the presence we may come to the conclusion that Midwinter Blood and In Darkness revolve around a few themes and three major literary techniques.

  9. Reduction in blood pressure and serum lipids by lycosome formulation of dark chocolate and lycopene in prehypertension

    Science.gov (United States)

    Petyaev, Ivan M; Dovgalevsky, Pavel Y; Chalyk, Natalia E; Klochkov, Victor; Kyle, Nigel H

    2014-01-01

    Twenty-nine healthy volunteers aged 47–69 years old were randomly assigned to a 28-day oral intake of different dark chocolate (DC) formulations. The main group received daily 30 g of proprietary lycopene-containing (L-tug) lycosome formulation of DC with enhanced bioavailability of cocoa flavanols. Two control groups daily consumed either 30 g of regular DC alone or along with 7 mg of lycopene, which corresponds to the amount of lycopene ingested with L-tug formulation. It was found that L-tug was more efficient in reducing diastolic blood pressure (mean value of −6.22 mmHg, 95% CI: 5.00, 8.00) when compared with the regular DC group (−3.00 mmHg, P < 0.05) or the group which ingested the DC and lycopene as two separate formulations (mean reduction of −4 mmHg, 95% CI: 2.47, 6.00, P = 0.0262). Only marginal superiority for L-tug formulation in the reduction in systolic blood pressure was seen. However, the L-tug formulation was the only formulation of DC which affected serum lipids. There was a reduction in total cholesterol (from median 228.00 mg/dL [95% CI: 206.2, 242.5] to 187.00 mg/dL [95% CI: 166.2, 202.2, P < 0.05]) with corresponding decline of low-density lipoprotein (LDL) cholesterol (from a median of 166.00 mg/dL [95% CI: 130.8, 177.0] to 151.00 mg/dL [95% CI: 122.8, 167.4; P < 0.05]) at the end of the intervention period. Similar decline was seen in serum triglycerides (P < 0.05). Serum high-density lipoprotein (HDL) cholesterol, glucose levels, and C-reactive protein (CRP) values remained statistically unchanged in all study groups throughout the intervention period. A superior biological activity of the L-tug lycosome formulation of DC extending beyond its antihypertensive effect to lipid-lowering ability opens up new possibilities for the use of DC for health purposes helping to reduce daily caloric intake without compromising on the health benefits of DC consumption. PMID:25493193

  10. 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

  11. Dark matter and dark energy

    CERN Multimedia

    Caldwell, Robert

    2009-01-01

    "Observations continue to indicate that the Universe is dominated by invisible components - dark matter and dark energy. Shedding light on this cosmic darkness is a priority for astronomers and physicists" (3 pages)

  12. The Effects of Dark Chocolate Consumption on Oxidative Stress and Blood Pressure in Patients with Metabolic Syndrome: A Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Hassan Mozaffari-Khosravi

    2016-10-01

    Full Text Available Background: Consumption of dark chocolate has been often hypothesized to have a role in the prevention of chronic diseases. The objective of this study was to investigate the effects of consumption of dark chocolate (DC on serum oxidative stress and blood pressure (BP in patients with metabolic syndrome (MetS. Methods: An 8-week parallel randomized clinical trial involving 114 patients with MetS was conducted on stable medication in 2014. Participants were randomly assigned to three groups: 1 consume 40 g/d DC (40G, 2 consume 20 g/d DC (20G, and 3 consume no DC as the control group (CG. BP, radical scavenging activity of 1-diphenyl-2-picrylhydrazyl (DPPH, and malondialdehyde (MDA were measured at baseline and after 8 weeks of intervention. Results: Mean age, weight, and body mass index (BMI of participants were 51.38 ± 6.95 y, 77.34 ± 12.86 kg, and 28.65 ± 4.4 kg/m2, respectively. No significant differences were found among the three groups in relation to these variables after the intervention. The mean change of systolic blood pressure in 40G, 20G, and CG were 0.31 ± 1.81, 0.37 ± 1.65, and 0.26 ± 1.56 mmHg (P = 0.3, respectively. These figures for diastolic blood pressure were obtained as 0.08 ± 1.03, -0.02 ± 1.12, and 0.22 ± 1.03 mmHg. No significant changes were observed in MDA and DPPH between three groups. Conclusion: Even daily intake of 40 g of DC with 76% purity for an 8-week period had no effect on body weight, BMI, BP, and oxidative stress in patients with MetS.

  13. 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

  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. 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.

  16. 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...... 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...

  17. 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.

  18. Dark Matter

    Indian Academy of Sciences (India)

    What You See Ain't What. You Got, Resonance, Vol.4,. No.9,1999. Dark Matter. 2. Dark Matter in the Universe. Bikram Phookun and Biman Nath. In Part 11 of this article we learnt that there are compelling evidences from dynamics of spiral galaxies, like our own, that there must be non-luminous matter in them. In this.

  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

    Science.gov (United States)

    Lincoln, Don

    2013-01-01

    It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of…

  1. 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.

  2. Dark Spots

    Science.gov (United States)

    2006-01-01

    Dark spots (left) and 'fans' appear to scribble dusty hieroglyphics on top of the Martian south polar cap in two high-resolution Mars Global Surveyor, Mars Orbiter Camera images taken in southern spring. Each image is about 3-kilometers wide (2-miles).

  3. Dark Matter

    Indian Academy of Sciences (India)

    In Part 11 of this article we learnt that there are compelling evidences from dynamics of spiral galaxies, like our own, that there must be non-luminous matter in them. In this second part we will see that even clusters of galaxies must harbour dark matter. As if this was not enough, it turns out that if our knowledge of the ...

  4. Dark Matter

    Indian Academy of Sciences (India)

    The study of gas clouds orbiting in the outer regions of spiral galaxies has revealed that their gravitational at- traction is much larger than the stars alone can provide. Over the last twenty years, astronomers have been forced to postulate the presence of large quantities of 'dark matter' to explain their observations. They are ...

  5. Dark Matter

    Indian Academy of Sciences (India)

    interests include cinema, stamps and sketching. GENERAL I ARTICLE. Dark Matter. 1. What You See Ain'/ What You Got. Bikram Phookun and Biman Nath. The study of gas clouds orbiting in the outer regions of spiral galaxies has revealed that their gravitational at- traction is much larger than the stars alone can provide.

  6. Blood

    Science.gov (United States)

    ... production of red blood cells, including: Iron deficiency anemia. Iron deficiency anemia is the most common type of anemia and ... inflammatory bowel disease are especially likely to have iron deficiency anemia. Anemia due to chronic disease. People with chronic ...

  7. Dark Tourism

    OpenAIRE

    Bali-Hudáková, Lenka

    2008-01-01

    This thesis is focused on the variability of the demand and the development of new trends in the fields of the tourism industry. Special attention is devoted to a new arising trend of the Dark Tourism. This trend has appeared in the end of the 20th century and it has gained the attraction of media, tourists, tourism specialists and other stakeholders. First part of the thesis is concerned with the variety of the tourism industry and the ethic question of the tourism development. The other par...

  8. 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.

  9. Differences in micronucleus induction in peripheral blood reticulocytes of mice exposed to N-ethyl-N-nitrosourea at light and dark dosing times.

    Science.gov (United States)

    Itoh, Keiichi; Masumori, Shoji; Nakajima, Madoka; Hayashi, Makoto; Sakakibara, Hiroyuki; Shimoi, Kayoko

    2012-01-01

    Mammals, including human beings, have a circadian clock system to regulate behavioral and physiological processes. In this study, we investigated the effect of dosing time on micronucleus induction in the bone marrow by evaluating the frequencies of micronucleated peripheral reticulocytes (MNRETs) in mice exposed to N-ethyl-N-nitrosourea (ENU) to assess any difference in genotoxic sensitivity to chemicals between light and dark periods (inactive phase for rodents and active phase for rodents). Male C3H/He mice were treated intraperitoneally with ENU (12.5 or 25 mg/kg body weight) at zeitgeber time (ZT) 3 in the light period or ZT15 in the dark period, and then the time courses of the frequencies of the MNRETs were determined. The frequencies of the MNRETs induced by ENU increased time-dependently and peaked at 48 hr after treatment for ZT3 and ZT15, and were obviously higher in the ZT15 treatment group than the ZT3 treatment group. The MNRETs were measured at 48 hr after treatment with ENU (25 mg/kg body weight) at various dosing times (ZT0, 3, 6, 12, 15 and 18). The frequencies of the MNRETs in mice treated at ZT0, 15 and 18 were significantly higher than those in mice treated at ZT3, 6 and 12. These results suggest that genotoxic sensitivity to chemicals in mouse bone marrow is different between light and dark periods maybe due to different biological responses (detoxification, cell cycle, DNA repair, etc.) related to circadian rhythms.

  10. Can dark matter decay in dark energy?

    International Nuclear Information System (INIS)

    Pereira, S. H.; Jesus, J. F.

    2009-01-01

    We analyze the interaction between dark energy and dark matter from a thermodynamical perspective. By assuming they have different temperatures, we study the possibility of occurring a decay from dark matter into dark energy, characterized by a negative parameter Q. We find that, if at least one of the fluids has nonvanishing chemical potential, for instance μ x dm =0 or μ x =0 and μ dm >0, the decay is possible, where μ x and μ dm are the chemical potentials of dark energy and dark matter, respectively. Using recent cosmological data, we find that, for a fairly simple interaction, the dark matter decay is favored with a probability of ∼93% over the dark energy decay. This result comes from a likelihood analysis where only background evolution has been considered.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.)

  1. 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.

  2. Baryonic Dark Matter

    OpenAIRE

    Silk, Joseph

    1994-01-01

    In the first two of these lectures, I present the evidence for baryonic dark matter and describe possible forms that it may take. The final lecture discusses formation of baryonic dark matter, and sets the cosmological context.

  3. 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.)

  4. 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.

  5. 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.

  6. Dark Matter Effective Theory

    DEFF Research Database (Denmark)

    Del Nobile, Eugenio; Sannino, Francesco

    2012-01-01

    We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff...... scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties....

  7. Dark stars: a review.

    Science.gov (United States)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  8. Nonthermal Supermassive Dark Matter

    Science.gov (United States)

    Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

    1999-01-01

    We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may he elementary particles of mass much greater than the weak scale. Searches for dark matter should ma be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

  9. 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.

  10. 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

  11. 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

  12. Collapsed Dark Matter Structures

    OpenAIRE

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-01-01

    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 elect...

  13. 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.

  14. Hunting the dark Higgs

    International Nuclear Information System (INIS)

    Duerr, Michael; Grohsjean, Alexander; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwanenberger, Christian; Penning, Bjoern

    2017-05-01

    We discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. We present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.

  15. 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...

  16. 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

  17. Dark discrete gauge symmetries

    International Nuclear Information System (INIS)

    Batell, Brian

    2011-01-01

    We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.

  18. Dark matter an introduction

    CERN Document Server

    Majumdar, Debasish

    2015-01-01

    Dark Matter: An Introduction tackles the rather recent but fast-growing subject of astroparticle physics, encompassing three main areas of fundamental physics: cosmology, particle physics, and astrophysics. Accordingly, the book discusses symmetries, conservation laws, relativity, and cosmological parameters and measurements, as well as the astrophysical behaviors of galaxies and galaxy clusters that indicate the presence of dark matter and the possible nature of dark matter distribution.

  19. 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

  20. Clumpy cold dark matter

    Science.gov (United States)

    Silk, Joseph; Stebbins, Albert

    1993-01-01

    A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

  1. 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

  2. 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

  3. Interacting dark matter and dark radiation

    Science.gov (United States)

    Tang, Yong

    2017-05-01

    We give a brief review on the interacting Dark Matter (iDM) scenario and its effects on cosmology and particle physics. If DM candidates can have strong self-interactions or interactions with other relativistic particles, we can refer them generally as iDM. IDM is an interesting possibility that is motivated both theoretically and observationally. The relativistic particles could belong to Standard Model (SM), such as photons and neutrinos, or be dark radiation (DR) in new physics. The resulting perturbed Boltzmann equations are concisely discussed and illustrations on matter power spectrum are given.

  4. 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.

  5. Baryonic Dark Matter

    OpenAIRE

    De Paolis, F.; Jetzer, Ph.; Ingrosso, G.; Roncadelli, M.

    1997-01-01

    Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic are discussed. Moreover, it is argued that most of the dark matter in galactic halos should be in the form of MACHOs and cold molecular clouds.

  6. The Dark Matter Problem

    NARCIS (Netherlands)

    Sanders, Robert H.

    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters

  7. Asymptotically Safe Dark Matter

    DEFF Research Database (Denmark)

    Sannino, Francesco; Shoemaker, Ian M.

    2015-01-01

    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting...... searches are the primary ways to constrain or discover asymptotically safe dark matter....

  8. Enabling forbidden dark matter

    Science.gov (United States)

    Cline, James M.; Liu, Hongwan; Slatyer, Tracy R.; Xue, Wei

    2017-10-01

    The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, 3 →2 annihilations can play an important role in determining the relic density over a broad range of model parameters. This occurs when the two-body annihilation is kinematically forbidden, but the 3 →2 process is allowed; we call this scenario not-forbidden dark matter. We illustrate this mechanism for a vector-portal dark matter model, showing that for a dark matter mass of mχ˜MeV -10 GeV , 3 →2 processes not only lead to the observed relic density, but also imply a self-interaction cross section that can solve the cusp/core problem. This can be accomplished while remaining consistent with stringent CMB constraints on light dark matter, and can potentially be discovered at future direct detection experiments.

  9. 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...

  10. Dark cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Ping-Kai, E-mail: pingkai.hu@physics.ucla.edu [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-1547 (United States); Kusenko, Alexander, E-mail: kusenko@ucla.edu [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-1547 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Takhistov, Volodymyr, E-mail: vtakhist@physics.ucla.edu [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-1547 (United States); Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697-4575 (United States)

    2017-05-10

    If dark matter particles have an electric charge, as in models of millicharged dark matter, such particles should be accelerated in the same astrophysical accelerators that produce ordinary cosmic rays, and their spectra should have a predictable rigidity dependence. Depending on the charge, the resulting “dark cosmic rays” can be detected as muon-like or neutrino-like events in Super-Kamiokande, IceCube, and other detectors. We present new limits and propose several new analyses, in particular, for the Super-Kamiokande experiment, which can probe a previously unexplored portion of the millicharged dark matter parameter space. Most of our results are fairly general and apply to a broad class of dark matter models.

  11. Dark cosmic rays

    Directory of Open Access Journals (Sweden)

    Ping-Kai Hu

    2017-05-01

    Full Text Available If dark matter particles have an electric charge, as in models of millicharged dark matter, such particles should be accelerated in the same astrophysical accelerators that produce ordinary cosmic rays, and their spectra should have a predictable rigidity dependence. Depending on the charge, the resulting “dark cosmic rays” can be detected as muon-like or neutrino-like events in Super-Kamiokande, IceCube, and other detectors. We present new limits and propose several new analyses, in particular, for the Super-Kamiokande experiment, which can probe a previously unexplored portion of the millicharged dark matter parameter space. Most of our results are fairly general and apply to a broad class of dark matter models.

  12. Fingerprinting Dark Energy

    CERN Document Server

    Sapone, Domenico

    2009-01-01

    Dark energy perturbations are normally either neglected or else included in a purely numerical way, obscuring their dependence on underlying parameters like the equation of state or the sound speed. However, while many different explanations for the dark energy can have the same equation of state, they usually differ in their perturbations so that these provide a fingerprint for distinguishing between different models with the same equation of state. In this paper we derive simple yet accurate approximations that are able to characterize a specific class of models (encompassing most scalar field models) which is often generically called "dark energy". We then use the approximate solutions to look at the impact of the dark energy perturbations on the dark matter power spectrum and on the integrated Sachs-Wolfe effect in the cosmic microwave background radiation.

  13. Resonant SIMP dark matter

    Directory of Open Access Journals (Sweden)

    Soo-Min Choi

    2016-07-01

    Full Text Available We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark U(1D. After the U(1D is broken down to a Z5 discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced 3→2 annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.

  14. Dark adaptation during transient hyperglycemia in type 2 diabetes

    DEFF Research Database (Denmark)

    Holfort, Stig Kragelund; Jackson, Gregory R; Larsen, Michael

    2010-01-01

    adaptometry was measured in one eye, chosen at random, using a computer-controlled dark adaptometer. Dark adaptation and capillary blood glucose were measured at baseline and 80 minutes into the OGTT/fasting test. Blood glucose remained stable throughout the examination in the 12 fasting subjects, whereas......It was the purpose of the present study to examine dark adaptation in subjects with type 2 diabetes during transient hyperglycemia. Twenty-four subjects with type 2 diabetes and minimal diabetic retinopathy were randomized to undergo an oral glucose tolerance test (OGTT) or to remain fasting. Dark...... glycemia increased in the 12 OGTT subjects, from 8.6±2.1 at baseline to 21.1±3.6 mM after 80 min. In the OGTT group, four out of seven subjects with delayed dark adaptation at baseline reached normal values during hyperglycemia. All examined aspects of rod adaptation were accelerated by hyperglycemia (time...

  15. Dark matter: the astrophysical case

    International Nuclear Information System (INIS)

    Silk, J.

    2012-01-01

    The identification of dark matter is one of the most urgent problems in cosmology. I describe the astrophysical case for dark matter, from both an observational and a theoretical perspective. This overview will therefore focus on the observational motivations rather than the particle physics aspects of dark matter constraints on specific dark matter candidates. First, however, I summarize the astronomical evidence for dark matter, then I highlight the weaknesses of the standard cold dark matter model (LCDM) to provide a robust explanation of some observations. The greatest weakness in the dark matter saga is that we have not yet identified the nature of dark matter itself

  16. 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.

  17. Dark Matter in ATLAS

    CERN Document Server

    Resconi, Silvia; The ATLAS collaboration

    2016-01-01

    Results of Dark Matter searches in mono-X analysis with the ATLAS experiment at the Large Hadron Collider are reported. The data were collected in proton–proton collisions at a centre-of-mass energy of 13 TeV and correspond to an integrated luminosity of 3.2 fb-1. A description of the main characteristics of each analysis and how the main backgrounds are estimated is shown. The observed data are in agreement with the expected Standard Model backgrounds for all analysis described. Exclusion limits are presented for Dark Matter models including pair production of dark matter candidates.

  18. Dark Matter in ATLAS

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00222441; The ATLAS collaboration

    2016-01-01

    An overview of Dark Matter searches with the ATLAS experiment at the Large Hadron Collider (LHC) is shown. Results of Mono-X analyses requiring large missing transverse momentum and a recoiling detectable physics object (X) are reported. The data were collected in proton-proton collisions at a centre-of-mass energy of 13 TeV. The observed data are in agreement with the expected Standard Model backgrounds for all analyses described. Exclusion limits are presented for Dark Matter models including pair production of Dark Matter candidates.

  19. Dark matter and dark energy solutions using by observational evidence

    Science.gov (United States)

    Demirel, E. C. Gunay; Yilmaz, I.

    2018-02-01

    In this study, we examine dark energy, dark matter and baryonic matter in FRW by observational evidences. Also we study our model by considering possible dark energy candidates such as Phantom energy. Obtained solutions show that dark energy candidate may be phantom energy depending on accuracy of today's observation.

  20. 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

  1. Dark Matter and Dark Energy Summary and Future Directions

    CERN Document Server

    Ellis, Jonathan Richard

    2003-01-01

    This paper reviews the progress reported at this Royal Society Discussion Meeting and advertizes some possible future directions in our drive to understand dark matter and dark energy. Additionally, a first attempt is made to place in context the exciting new results from the WMAP satellite, which were published shortly after this Meeting. In the first part of this review, pieces of observational evidence shown here that bear on the amounts of dark matter and dark energy are reviewed. Subsequently, particle candidates for dark matter are mentioned, and detection strategies are discussed. Finally, ideas are presented for calculating the amounts of dark matter and dark energy, and possibly relating them to laboratory data.

  2. Inelastic dark matter

    International Nuclear Information System (INIS)

    Smith, David; Weiner, Neal

    2001-01-01

    Many observations suggest that much of the matter of the universe is nonbaryonic. Recently, the DAMA NaI dark matter direct detection experiment reported an annual modulation in their event rate consistent with a WIMP relic. However, the Cryogenic Dark Matter Search (CDMS) Ge experiment excludes most of the region preferred by DAMA. We demonstrate that if the dark matter can only scatter by making a transition to a slightly heavier state (Δm∼100 keV), the experiments are no longer in conflict. Moreover, differences in the energy spectrum of nuclear recoil events could distinguish such a scenario from the standard WIMP scenario. Finally, we discuss the sneutrino as a candidate for inelastic dark matter in supersymmetric theories

  3. Xenophobic dark matter

    Science.gov (United States)

    Feng, Jonathan L.; Kumar, Jason; Sanford, David

    2013-07-01

    We consider models of xenophobic dark matter, in which isospin-violating dark matter-nucleon interactions significantly degrade the response of xenon direct detection experiments. For models of near-maximal xenophobia, with neutron-to-proton coupling ratio fn/fp≈-0.64, and dark matter mass near 8 GeV, the regions of interest for CoGeNT and CDMS-Si and the region of interest identified by Collar and Fields in CDMS-Ge data can be brought into agreement. This model may be tested in future direct, indirect, and collider searches. Interestingly, because the natural isotope abundance of xenon implies that xenophobia has its limits, we find that this xenophobic model may be probed in the near future by xenon experiments. Near-future data from the LHC and Fermi-LAT may also provide interesting alternative probes of xenophobic dark matter.

  4. Dark matter warms up

    CERN Multimedia

    Peplow, Mark

    2006-01-01

    "Unseen mass looks to be more "tepid" than thought. Astronomers have measured the temperature of dark matter for the first time. The discovery should help particle hunters to identify exactly what this mysterious substance is made of" (1 page)

  5. Cleaning up dark matter

    CERN Multimedia

    Bignami, Giovanni Fabrizio

    2006-01-01

    "An experiment in Italy has found tantalizing but puzzling evidence for axions, one if the leading candidates for dark matter. The authors explain how a pair of spinning neutron stars should settle the issue once and for all." (3 pages)

  6. Little composite dark matter.

    Science.gov (United States)

    Balkin, Reuven; Perez, Gilad; Weiler, Andreas

    2018-01-01

    We examine the dark matter phenomenology of a composite electroweak singlet state. This singlet belongs to the Goldstone sector of a well-motivated extension of the Littlest Higgs with T -parity. A viable parameter space, consistent with the observed dark matter relic abundance as well as with the various collider, electroweak precision and dark matter direct detection experimental constraints is found for this scenario. T -parity implies a rich LHC phenomenology, which forms an interesting interplay between conventional natural SUSY type of signals involving third generation quarks and missing energy, from stop-like particle production and decay, and composite Higgs type of signals involving third generation quarks associated with Higgs and electroweak gauge boson, from vector-like top-partners production and decay. The composite features of the dark matter phenomenology allows the composite singlet to produce the correct relic abundance while interacting weakly with the Higgs via the usual Higgs portal coupling [Formula: see text], thus evading direct detection.

  7. Inflatable Dark Matter.

    Science.gov (United States)

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D

    2016-01-22

    We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ∼MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.

  8. Lectures on dark matter

    International Nuclear Information System (INIS)

    Seljak, U.

    2001-01-01

    These lectures concentrate on evolution and generation of dark matter perturbations. The purpose of the lectures is to present, in a systematic way, a comprehensive review of the cosmological parameters that can lead to observable effects in the dark matter clustering properties. We begin by reviewing the relativistic linear perturbation theory formalism. We discuss the gauge issue and derive Einstein's and continuity equations for several popular gauge choices. We continue by developing fluid equations for cold dark matter and baryons and Boltzmann equations for photons, massive and massless neutrinos. We then discuss the generation of initial perturbations by the process of inflation and the parameters of that process that can be extracted from the observations. Finally we discuss evolution of perturbations in various regimes and the imprint of the evolution on the dark matter power spectrum both in the linear and in the nonlinear regime. (author)

  9. The Dark Universe

    Science.gov (United States)

    Livio, Mario

    2010-04-01

    1. A brief history of dark matter Vera Rubin; 2. Microlensing towards the Magellanic Clouds Kailash Sahu; 3. Searching for galactic dark matter Harvey Richer; 4. Hot gas in clusters of galaxies and Omega Megan Donahue; 5. Tracking the Baryon density from the Big Bang to the present Gary Steigman; 6. Modified Newtonian dynamics and its implications Bob Sanders; 7. Cosmological parameters and quintessence from radio galaxies Ruth Daly and Eric Guerra; 8. The mass density of the Universe Neta Bahcall; 9. Growth of structure in the Universe John Peacock; 10. Cosmological implications of the most distant supernova (known) Adam Riess; 11. Dynamical probes of the Halo mass function Chris Kochanek; 12. Detection of gravitational waves from inflation Marc Kamionkowski and Andrew Jaffe; 13. Cosmological constant problems and their solution Alex Vilenkin; 14. Dark Matter and dark energy: a physicist's perspective Michael Dine.

  10. Gravity's dark side: Doing without dark matte

    International Nuclear Information System (INIS)

    Chalmers, M.

    2006-01-01

    Despite decades of searching, the 'dark matter' thought to hold galaxies together is still nowhere to be found. Matthew Chalmers describes how some physicists think it makes more sense to change our theory of gravity instead. Einstein's general theory of relativity is part of the bedrock of modern physics. It describes in elegant mathematical terms how matter causes space-time to curve, and therefore how objects move in a gravitational field. Since it was published in 1916, general relativity has passed every test asked of it with flying colours, and to many physicists the notion that it is wrong is sacrilege. But the motivation for developing an alternative theory of gravity is compelling. Over the last few years cosmologists have arrived at a simple yet extraordinarily successful model of universe. The trouble is that it requires most of the cosmos to be filled with mysterious stuff that we cannot see. In particular, general relativity - or rather its non-relativistic limit otherwise known as Newtonian gravity - can only correctly describe the dynamics of galaxies if we invoke huge quantities of 'dark matter'. Furthermore, an exotic entity called dark energy is necessary to account for the recent discovery that the expansion of the universe is accelerating. Indeed, in the standard model of cosmology, visible matter such as stars, planets and physics textbooks accounts for just 4% of the total universe. (U.K.)

  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. 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

  14. 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.

  15. 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.

  16. Probes for Dark Matter Physics

    OpenAIRE

    Khlopov, Maxim Yu.

    2018-01-01

    The existence of cosmological dark matter is in the bedrock of the modern cosmology. The dark matter is assumed to be nonbaryonic and to consist of new stable particles. However if composite dark matter contains stable electrically charged leptons and quarks bound by ordinary Coulomb interaction in elusive dark atoms, these charged constituents of dark atoms can be the subject of direct experimental test at the colliders. In such models the excessive negatively double charged particles are bo...

  17. Working the Dark Side

    DEFF Research Database (Denmark)

    Bjering, Jens Christian Borrebye

    A few days after the terror attacks of 9/11, then Vice President Dick Cheney appeared on television with a call for “working the dark side.” While still unclear what this expression entailed at the time, Cheney's comment appears in retrospect to almost have been prophetic for the years to come...... – years where parts of the U.S. Army and intelligence community set up a rampant torture regime all across the world. Yet, the connection between a so-called “dark side,” “working” this “dark side,” and the torture that followed is not a given, but, instead, a consequence of a set of very specific legal......, political, and personal choices in the early years after 9/11. This dissertation is an investigation into how the notion of a “dark side” took form, and of how and why the specific make-up of this“dark side” ended up creating a torture regime which already today seems almost unreal. The dissertation's first...

  18. Dark matter detection - II

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the mysterious missing mass of the universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world-wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  19. Dark matter detection - III

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the missing mass of the universe has become one of the big challenges of todays particle physics and cosmology. Astronomical observations show that only 1% of the matter of the Universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the Universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world- wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  20. Dark matter detection - I

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the mysterious missing mass of the universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world-wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  1. 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

  2. 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.

  3. Dark adaptation during transient hyperglycemia in type 2 diabetes

    DEFF Research Database (Denmark)

    Holfort, Stig Kraglund; Jackson, Gregory R; Larsen, Michael

    2010-01-01

    It was the purpose of the present study to examine dark adaptation in subjects with type 2 diabetes during transient hyperglycemia. Twenty-four subjects with type 2 diabetes and minimal diabetic retinopathy were randomized to undergo an oral glucose tolerance test (OGTT) or to remain fasting. Dark...... adaptometry was measured in one eye, chosen at random, using a computer-controlled dark adaptometer. Dark adaptation and capillary blood glucose were measured at baseline and 80 minutes into the OGTT/fasting test. Blood glucose remained stable throughout the examination in the 12 fasting subjects, whereas...... to rod-cone break -26%; time to rod intercept -16%, rod sensitivity recovery slope (log units/min) +35%), whereas no measurable change in cone adaptation was seen. The results are consistent with rod adaptation being limited by glycemia and with rod adaptation being delayed in subjects with diabetes...

  4. Asymmetric Higgsino dark matter.

    Science.gov (United States)

    Blum, Kfir; Efrati, Aielet; Grossman, Yuval; Nir, Yosef; Riotto, Antonio

    2012-08-03

    In the supersymmetric framework, prior to the electroweak phase transition, the existence of a baryon asymmetry implies the existence of a Higgsino asymmetry. We investigate whether the Higgsino could be a viable asymmetric dark matter candidate. We find that this is indeed possible. Thus, supersymmetry can provide the observed dark matter abundance and, furthermore, relate it with the baryon asymmetry, in which case the puzzle of why the baryonic and dark matter mass densities are similar would be explained. To accomplish this task, two conditions are required. First, the gauginos, squarks, and sleptons must all be very heavy, such that the only electroweak-scale superpartners are the Higgsinos. With this spectrum, supersymmetry does not solve the fine-tuning problem. Second, the temperature of the electroweak phase transition must be low, in the (1-10) GeV range. This condition requires an extension of the minimal supersymmetric standard model.

  5. 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.

  6. Periodically modulated dark states

    Science.gov (United States)

    Han, Yingying; Zhang, Jun; Zhang, Wenxian

    2018-04-01

    Phenomena of electromagnetically induced transparency (PEIT) may be interpreted by the Autler-Townes Splitting (ATS), where the coupled states are split by the coupling laser field, or by the quantum destructive interference (QDI), where the atomic phases caused by the coupling laser and the probe laser field cancel. We propose modulated experiments to explore the PEIT in an alternative way by periodically modulating the coupling and the probe fields in a Λ-type three-level system initially in a dark state. Our analytical and numerical results rule out the ATS interpretation and show that the QDI interpretation is more appropriate for the modulated experiments. Interestingly, dark state persists in the double-modulation situation where control and probe fields never occur simultaneously, which is significant difference from the traditional dark state condition. The proposed experiments are readily implemented in atomic gases, artificial atoms in superconducting quantum devices, or three-level meta-atoms in meta-materials.

  7. Dark chocolate exacerbates acne.

    Science.gov (United States)

    Vongraviopap, Saivaree; Asawanonda, Pravit

    2016-05-01

    The effects of chocolate on acne exacerbations have recently been reevaluated. For so many years, it was thought that it had no role in worsening acne. To investigate whether 99% dark chocolate, when consumed in regular daily amounts, would cause acne to worsen in acne-prone male subjects, twenty-five acne prone male subjects were asked to consume 25 g of 99% dark chocolate daily for 4 weeks. Assessments which included Leeds revised acne scores as well as lesion counts took place weekly. Food frequency questionnaire was used, and daily activities were recorded. Statistically significant changes of acne scores and numbers of comedones and inflammatory papules were detected as early as 2 weeks into the study. At 4 weeks, the changes remained statistically significant compared to baseline. Dark chocolate when consumed in normal amounts for 4 weeks can exacerbate acne in male subjects with acne-prone skin. © 2015 The International Society of Dermatology.

  8. WISPy cold dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Arias, Paola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Cadamuro, Davide; Redondo, Javier [Max-Planck-Institut fuer Physik, Muenchen (Germany); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-01-15

    Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches - exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques - can probe large parts of this parameter space in the foreseeable future. (orig.)

  9. Cosmology and Dark Matter

    CERN Document Server

    Tkachev, Igor

    2017-01-01

    This lecture course covers cosmology from the particle physicist perspective. Therefore, the emphasis will be on the evidence for the new physics in cosmological and astrophysical data together with minimal theoretical frameworks needed to understand and appreciate the evidence. I review the case for non-baryonic dark matter and describe popular models which incorporate it. In parallel, the story of dark energy will be developed, which includes accelerated expansion of the Universe today, the Universe origin in the Big Bang, and support for the Inflationary theory in CMBR data.

  10. 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 .

  11. Dark matter and its detection

    International Nuclear Information System (INIS)

    Bi Xiaojun; Qin Bo

    2011-01-01

    We first explain the concept of dark matter,then review the history of its discovery and the evidence of its existence. We describe our understanding of the nature of dark matter particles, the popular dark matter models,and why the weakly interacting massive particles (called WIMPs) are the most attractive candidates for dark matter. Then we introduce the three methods of dark matter detection: colliders, direct detection and indirect detection. Finally, we review the recent development of dark matter detection, including the new results from DAMA, CoGent, PAMELA, ATIC and Fermi. (authors)

  12. 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

  13. 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

  14. 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

  15. Sterile neutrino portal to Dark Matter II: exact dark symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, Miguel; Rius, Nuria [Universidad de Valencia-CSIC, Departamento de Fisica Teorica and IFIC, C/Catedratico Jose Beltran, 2, 46980, Paterna (Spain); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-06-15

    We analyze a simple extension of the standard model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV. (orig.)

  16. 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...

  17. Dichromatic dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yang; Su, Meng; Zhao, Yue

    2013-02-01

    Both the robust INTEGRAL 511 keV gamma-ray line and the recent tentative hint of the 135 GeV gamma-ray line from Fermi-LAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the low-energy positrons for INTEGRAL, dark matter particles annihilate into a complex scalar that couples to photon via a charge-radius operator. The complex scalar contains an excited state decaying into the ground state plus an off-shell photon to generate a pair of positron and electron. Two charged particles with non-degenerate masses are necessary for generating this charge-radius operator. One charged particle is predicted to be long-lived and have a mass around 3.8 TeV to explain the dark matter thermal relic abundance from its late decay. The other charged particle is predicted to have a mass below 1 TeV given the ratio of the two signal cross sections. The 14 TeV LHC will concretely test the main parameter space of this lighter charged particle.

  18. Asymmetric condensed dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, Anthony; Diez-Tejedor, Alberto, E-mail: aguirre@scipp.ucsc.edu, E-mail: alberto.diez@fisica.ugto.mx [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA, 95064 (United States)

    2016-04-01

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate must be lighter than a few tens of eV so that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles.

  19. Dark matter axions '96

    International Nuclear Information System (INIS)

    Sikivie, P.

    1996-01-01

    This report discusses why axions have been postulated to exist, what cosmology implies about their presence as cold dark matter in the galactic halo, how axions might be detected in cavities wherein strong magnetic fields stimulate their conversion into photons, and relations between axions' energy spectra and galactic halos' properties

  20. Dark matter candidates

    International Nuclear Information System (INIS)

    Turner, M.S.

    1989-01-01

    One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of? Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs

  1. Dark Barchan Dunes

    Science.gov (United States)

    2004-01-01

    13 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows north polar sand dunes in the summertime. During winter and early spring, north polar dunes are covered with bright frost. When the frost sublimes away, the dunes appear darker than their surroundings. To a geologist, sand has a very specific meaning. A sand grain is defined independently of its composition; it is a particle with a size between 62.5 and 2000 microns. Two thousand microns equals 2 millimeters. The dunes are dark because they are composed of sand grains made of dark minerals and/or rock fragments. Usually, dark grains indicate the presence of unoxidized iron, for example, the dark volcanic rocks of Hawaii, Iceland, and elsewhere. This dune field is located near 71.7oN, 51.3oW. Dune slip faces indicate winds that blow from the upper left toward lower right. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

  2. with dark matter

    Indian Academy of Sciences (India)

    2012-11-16

    Nov 16, 2012 ... to have a dramatic impact on neutrino physics, dark matter and all fermion masses and mixings. Keywords. Radiative see-saw; fermion masses; grand unification. PACS Nos 12.10.Dm; 12.60.Jv; 14.60.Pq. 1. Introduction. In SO(10) grand unified theory which contains all standard fermions of one generation.

  3. Template Composite Dark Matter

    DEFF Research Database (Denmark)

    Drach, Vincent; Hietanen, Ari; Pica, Claudio

    2015-01-01

    We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. We discuss how the model can be used as a template for composite Dark Matter (DM). We estimate one particular interaction of the DM candidate with the Standard Model : the interaction through photon...

  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. Little composite dark matter

    Science.gov (United States)

    Balkin, Reuven; Perez, Gilad; Weiler, Andreas

    2018-02-01

    We examine the dark matter phenomenology of a composite electroweak singlet state. This singlet belongs to the Goldstone sector of a well-motivated extension of the Littlest Higgs with T-parity. A viable parameter space, consistent with the observed dark matter relic abundance as well as with the various collider, electroweak precision and dark matter direct detection experimental constraints is found for this scenario. T-parity implies a rich LHC phenomenology, which forms an interesting interplay between conventional natural SUSY type of signals involving third generation quarks and missing energy, from stop-like particle production and decay, and composite Higgs type of signals involving third generation quarks associated with Higgs and electroweak gauge boson, from vector-like top-partners production and decay. The composite features of the dark matter phenomenology allows the composite singlet to produce the correct relic abundance while interacting weakly with the Higgs via the usual Higgs portal coupling λ _{ {DM}}˜ O(1%), thus evading direct detection.

  6. Simplified Dark Matter Models

    OpenAIRE

    Morgante, Enrico

    2018-01-01

    I review the construction of Simplified Models for Dark Matter searches. After discussing the philosophy and some simple examples, I turn the attention to the aspect of the theoretical consistency and to the implications of the necessary extensions of these models.

  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 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

  9. 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)

  10. 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

  11. Non-baryonic dark matter

    International Nuclear Information System (INIS)

    Berkes, I.

    1996-01-01

    This article discusses the nature of the dark matter and the possibility of the detection of non-baryonic dark matter in an underground experiment. Among the useful detectors the low temperature bolometers are considered in some detail. (author)

  12. An elusive vector dark matter

    Directory of Open Access Journals (Sweden)

    Chuan-Ren Chen

    2015-02-01

    Full Text Available Even though the sensitivity of direct dark matter search experiments reaches the level of about 10−45 cm2, no confident signal of dark matter has been observed. We point out that, if dark matter is a vector boson, the null result in direct dark matter search experiments may be due to the destructive effects in dark-matter–nucleon elastic scattering. We illustrate the scenario using a modified Higgs portal model that includes exotic quarks. The significant cancellation can occur for a certain mass gap between new heavy quark and dark matter. As a result, the spin-independent dark-matter–nucleon elastic scattering is so suppressed that the future direct search experiments will hardly observe the signal of dark matter.

  13. Welcome to the dark side

    CERN Multimedia

    Hogan, Jenny

    2007-01-01

    "Physicists says that 96% of the Universe is unseen, and appeal tot he ideas of "dark matter" and "dark energy" to make up the difference. In the first of two articles, jeanny hogan reports that attempts to identify the mysterious dark matter are on the verge of success. In the second, Geoff Brumfiel asks why dark energy, hailed as a breakthrough when discovered a decade ago, is proving more frustrating than ever tot he scientists who study it." (4,5 pages)

  14. Signals of Supersymmetric Dark Matter

    OpenAIRE

    Abbas, Afsar

    1999-01-01

    The Lightest Supersymmetric Particle predicted in most of the supersymmetric scenarios is an ideal candidate for the dark matter of cosmology. Their detection is of extreme significance today. Recently there have been intriguing signals of a 59 Gev neutralino dark matter at DAMA in Gran Sasso. We look at other possible signatures of dark matter in astrophysical and geological frameworks. The passage of the earth through dense clumps of dark matter would produce large quantities of heat in the...

  15. Black Holes as Dark Matter

    OpenAIRE

    Frampton, Paul H.

    2009-01-01

    While the energy of the universe has been established to be about 0.04 baryons, 0.24 dark matter and 0.72 dark energy, the cosmological entropy is almost entirely, about $(1 - 10^{-15})$, from black holes and only $10^{-15}$ from everything else. This identification of all dark matter as black holes is natural in statistical mechanics. Cosmological history of dark matter is discussed.

  16. Caustic rings of dark matter

    OpenAIRE

    Sikivie, Pierre

    1997-01-01

    It is shown that the infall of collisionless dark matter onto isolated galaxies produces a series of caustic rings in the halo dark matter distribution. The properties of these caustics are investigated. The density profile of the caustic is derived for a specific case. Bumps in the rotation curve of NGC 3198 are interpreted as due to caustic rings of dark matter.

  17. Dark Matter Searches at LHC

    CERN Document Server

    Terashi, Koji; The ATLAS collaboration

    2017-01-01

    This talk will present dark matter searches at the LHC in the PIC2017 conference. The main emphasis is placed on the direct dark matter searches while the interpretation of searches for SUSY and invisible Higgs signals for the dark matter is also presented.

  18. The DarkSide Program

    Directory of Open Access Journals (Sweden)

    Rossi B.

    2016-01-01

    Full Text Available DarkSide-50 at Gran Sasso underground laboratory (LNGS, Italy, is a direct dark matter search experiment based on a liquid argon TPC. DS-50 has completed its first dark matter run using atmospheric argon as target. The detector performances and the results of the first physics run are presented in this proceeding.

  19. How dark chocolate is processed

    Science.gov (United States)

    This month’s column will continue the theme of “How Is It Processed?” The column will focus on dark chocolate. The botanical name for the cacao tree is Theobroma cacao, which literally means “food of the Gods.” Dark chocolate is both delicious and nutritious. Production of dark chocolate will be des...

  20. 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

  1. Accelerated whole brain intracranial vessel wall imaging using black blood fast spin echo with compressed sensing (CS-SPACE).

    Science.gov (United States)

    Zhu, Chengcheng; Tian, Bing; Chen, Luguang; Eisenmenger, Laura; Raithel, Esther; Forman, Christoph; Ahn, Sinyeob; Laub, Gerhard; Liu, Qi; Lu, Jianping; Liu, Jing; Hess, Christopher; Saloner, David

    2017-12-05

    Develop and optimize an accelerated, high-resolution (0.5 mm isotropic) 3D black blood MRI technique to reduce scan time for whole-brain intracranial vessel wall imaging. A 3D accelerated T 1 -weighted fast-spin-echo prototype sequence using compressed sensing (CS-SPACE) was developed at 3T. Both the acquisition [echo train length (ETL), under-sampling factor] and reconstruction parameters (regularization parameter, number of iterations) were first optimized in 5 healthy volunteers. Ten patients with a variety of intracranial vascular disease presentations (aneurysm, atherosclerosis, dissection, vasculitis) were imaged with SPACE and optimized CS-SPACE, pre and post Gd contrast. Lumen/wall area, wall-to-lumen contrast ratio (CR), enhancement ratio (ER), sharpness, and qualitative scores (1-4) by two radiologists were recorded. The optimized CS-SPACE protocol has ETL 60, 20% k-space under-sampling, 0.002 regularization factor with 20 iterations. In patient studies, CS-SPACE and conventional SPACE had comparable image scores both pre- (3.35 ± 0.85 vs. 3.54 ± 0.65, p = 0.13) and post-contrast (3.72 ± 0.58 vs. 3.53 ± 0.57, p = 0.15), but the CS-SPACE acquisition was 37% faster (6:48 vs. 10:50). CS-SPACE agreed with SPACE for lumen/wall area, ER measurements and sharpness, but marginally reduced the CR. In the evaluation of intracranial vascular disease, CS-SPACE provides a substantial reduction in scan time compared to conventional T 1 -weighted SPACE while maintaining good image quality.

  2. 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.

  3. Dark Skies Rangers

    Science.gov (United States)

    Doran, Rosa

    2015-08-01

    Creating awareness about the importance of the protection of our dark skies is the main goal of the Dark Skies Rangers project, a joint effort from the NOAO and the Galileo Teacher Training Program. Hundreds of schools and thousands of students have been reached by this program. We will focus in particular on the experience being developed in Portugal where several municipalities have now received street light auditing produced by students with suggestions on how to enhance the energy efficiency of illumination of specific urban areas. In the International Year of Light we are investing our efforts in exporting the successful Portuguese experience to other countries. The recipe is simple: train teachers, engage students, foster the participation of local community and involve local authorities in the process. In this symposium we hope to draft the cookbook for the near future.

  4. CN in dark clouds

    International Nuclear Information System (INIS)

    Churchwell, E.; Bieging, J.H.

    1983-01-01

    We have detected CN (N = 1--0) emission toward six locations in the Taurus dark cloud complex, but not toward L183 or B227. The two hyperfine components, F = 3/2--1/2 and F = 5/2--3/2 (of J = 3/2--1/2), have intensity ratios near unity toward four locations in Taurus, consistent with large line optical depths. CN column densities are found to be > or approx. =6 x 10 13 cm -2 in those directions where the hyperfine ratios are near unity. By comparing CN with NH 3 and C 18 O column densities, we find that the relative abundance of CN in the Taurus cloudlets is at least a factor of 10 greater than in L183. In this respect, CN fits the pattern of enhanced abundances of carbon-bearing molecules (in partricular the cyanopolyynes) in the Taurus cloudlets relative to similar dark clouds outside Taurus

  5. Dark matter from unification

    DEFF Research Database (Denmark)

    Kainulainen, Kimmo; Tuominen, Kimmo; Virkajärvi, Jussi Tuomas

    2013-01-01

    We consider a minimal extension of the Standard Model (SM), which leads to unification of the SM coupling constants, breaks electroweak symmetry dynamically by a new strongly coupled sector and leads to novel dark matter candidates. In this model, the coupling constant unification requires...... eigenstates of this sector and determine the resulting relic density. The results are constrained by available data from colliders and direct and indirect dark matter experiments. We find the model viable and outline briefly future research directions....... the existence of electroweak triplet and doublet fermions singlet under QCD and new strong dynamics underlying the Higgs sector. Among these new matter fields and a new right handed neutrino, we consider the mass and mixing patterns of the neutral states. We argue for a symmetry stabilizing the lightest mass...

  6. Baryonic dark matter

    Science.gov (United States)

    Silk, Joseph

    1991-01-01

    Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

  7. 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)

  8. Dark Web 101

    Science.gov (United States)

    2016-07-21

    input data to get access (email or online banks), unlinked content (unpublished blogs or or- ganizational databases), proprietary data (study results...reigns, enables darknet communication. One Chinese blogger who established a darknet blog said “This is a free Chinese Internet world, here you can...thought my first contact with the dark web would be on a Chinese website. I hope the webmaster continues their good work13.” These tactics reflect

  9. Dark Sand Dunes

    Science.gov (United States)

    2005-01-01

    13 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in the north polar region of Mars. The dominant winds responsible for these dunes blew from the lower left (southwest). They are located near 76.6oN, 257.2oW. The picture covers an area 3 km (1.9 mi) across; sunlight illuminates the scene from the upper right.

  10. DARK MATTER: Optical shears

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    Evidence for dark matter continues to build up. Last year (December 1993, page 4) excitement rose when the French EROS (Experience de Recherche d'Objets Sombres) and the US/Australia MACHO collaborations reported hints that small inert 'brown dwarf stars could provide some of the Universe's missing matter. In the 1930s, astronomers first began to suspect that there is a lot more to the Universe than meets the eye

  11. Dark matter wants Linear Collider

    International Nuclear Information System (INIS)

    Matsumoto, S.; Asano, M.; Fujii, K.; Takubo, Y.; Honda, T.; Saito, T.; Yamamoto, H.; Humdi, R.S.; Ito, H.; Kanemura, S; Nabeshima, T.; Okada, N.; Suehara, T.

    2011-01-01

    One of the main purposes of physics at the International Linear Collider (ILC) is to study the property of dark matter such as its mass, spin, quantum numbers, and interactions with particles of the standard model. We discuss how the property can or cannot be investigated at the ILC using two typical cases of dark matter scenario: 1) most of new particles predicted in physics beyond the standard model are heavy and only dark matter is accessible at the ILC, and 2) not only dark matter but also other new particles are accessible at the ILC. We find that, as can be easily imagined, dark matter can be detected without any difficulties in the latter case. In the former case, it is still possible to detect dark matter when the mass of dark matter is less than a half mass of the Higgs boson.

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

    Science.gov (United States)

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

    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 fncdm 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 fncdm100 keV range they are fncdm<=0.43 (0.45), respectively.

  13. 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.

  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. 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.

  16. 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

  17. 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

  18. 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.

  19. Dark Martian Dunes

    Science.gov (United States)

    2005-01-01

    30 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, windblown sand dunes in a crater in the Hesperia region of Mars. The steepest slopes on the dunes -- their slipfaces -- point toward the south-southwest, indicating that the winds responsible for the dunes blew from the north-northeast (top/upper right). Location near: 12.4oS, 236.5oW Image width: 3 km (1.9 mi) Illumination from: upper left Season Southern Spring

  20. Dark Polar Dunes

    Science.gov (United States)

    2005-01-01

    20 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer in December 2004, shows dark, windblown sand dunes in the north polar region of Mars. A vast sea of sand dunes nearly surrounds the north polar cap. These landforms are located near 80.3oN, 144.1oW. Light-toned features in the image are exposures of the substrate that underlies the dune field. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.

  1. Dark matter in the universe

    International Nuclear Information System (INIS)

    Opher, Reuven

    2001-01-01

    We treat here the problem of dark matter in galaxies. Recent articles seem to imply that we are entering into the precision era of cosmology, implying that all of the basic physics of cosmology is known. However, we show here that recent observations question the pillar of the standard model: the presence of nonbaryonic 'dark matter' in galaxies. Using Newton's law of gravitation, observations indicate that most of the matter in galaxies in invisible or dark. From the observed abundances of light elements, dark matter in galaxies must be primarily nonbaryonic. The standard model and its problems in explaining nonbaryonic dark matter will first be discussed. This will be followed by a discussion of a modification of Newton's law of gravitation to explain dark matter in galaxies. (author)

  2. Quantum vacuum and dark matter

    CERN Document Server

    Hajdukovic, Dragan Slavkov

    2012-01-01

    Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.

  3. 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.

  4. Astrophysical probes of dark matter

    Science.gov (United States)

    Hurst, Travis J.

    In the ACDM model,≈ 26% of the matter-energy content of the Universe is in the form of an unidentified Cold Dark Matter. Observations indicate that the Dark Matter is a new exotic particle not accounted for in the Standard Model of particle physics. Identifying the Dark Matter particle is one of the most pressing problems in cosmology and particle physics. In this thesis we investigate several possible astrophysical signatures of Dark Matter: Dark Matter annihilations in cold White Dwarfs provide a source of luminosity that could halt their cooling. This effect can be used to constrain the Dark Matter density local to the White Dwarf. In the case of the coldest White Dwarf in a Globular Cluster, a constraint on the maximum Dark Matter content is derived. Globular Clusters do not appear to have Dark Matter halos today, but could have possessed them in the past. We investigate whether Globular Clusters could have lost their halos through multi-body gravitational interactions--we find that this scenario is unlikely. Finally, we explore the effects of Asymmetric Dark Matter on stellar evolution. Asymmetric Dark Matter can alter the transport of energy in the cores of stars. We show that this has potentially observable effects on low mass Main Sequence and post-Main Sequence stars. Our main conclusion is that astrophysical observations can potentially rule out some Dark Matter models. On the other hand, if the properties of the Dark Matter particle become known, then its astrophysical effects must be taken into account when evaluating observations.

  5. Caustic rings of dark matter

    International Nuclear Information System (INIS)

    Sikivie, P.

    1997-01-01

    It is shown that the infall of collisionless dark matter onto isolated galaxies produce a series of caustic rings in the halo dark matter distribution. The properties of these caustics are investigated. It is found in particular that the density profile of the caustic behaves as the inverse distance to the ring. Bumps in the rotation curve of NGC 3198 are interpreted as due to caustic rings of dark matter

  6. The DarkSide project

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P.; Agostino, L.; Albuquerque, Ivone Freire Da Mota; Alexander, Thomas R.; Alton, A.; Arisaka, K.; Back, Henning O.; Baldin, B.; Biery, K.; Bonfini, G.; Bossa, M.; Bottino, Bianca; Brigatti, A.; Brodsky, J.; Budano, F.; Bussino, Severino; Cadeddu, Matteo; Cadonati, L.; Cadoni, M.; Calaprice, F.; Canci, N.; Candela, A.; Cao, H.; Cariello, M.; Carlini, Macro; Catalanotti, Sergio; Cavalcante, P.; Chepurnov, A.; Cocco, A. G.; Covone, G.; Crippa, L.; D' Angelo, D.; D' Incecco, M.; Davini, S.; De Cecco, Sandro; De Deo, M.; De Vincenzi, Mario; Derbin, A.; Devoto, A.; Di Eusanio, F.; Di Pietro, Giuseppe; Edkins, E.; Empl, Anton; Fan, A.; Fiorillo, G.; Fomenko, K.; Forster, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Giganti, C.; Goretti, A.; Granato, Francesco; Grandi, L.; Gromov, M.; Guan, M. Y.; Guardincerri, Y.; Hackett, B.; Herner, K.; Hungerford, Edward; Ianni, Al.; Ianni, An.; James, I.; Jollet, C.; Keeter, K.; Kendziora, C.; Kobychev, V.; Koh, G.; Korablev, D.; Korga, G.; Kubankin, Alexander; Li, X.; Lissia, M.; Lombardi, P.; Luitz, S.; Ma, Y. Q.; Machulin, I.; Mandarano, A.; Mari, S. M.; Maricic, J.; Marini, L.; Martoff, J.; Meregaglia, A.; Meyers, P. D.; Miletic, T.; Milincic, R.; Montanari, D.; Monte, Alissa; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B.; Muratova, V.; Musico, P.; Napolitano, James; Nelson, A.; Odrowski, S.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, Marco; Pantic, E.; Parmeggiano, S.; Pelczar, K.; Pelliccia, N.; Perasso, S.; Pocar, A.; Pordes, S.; Pugachev, D.; Qian, H.; Randle, K.; Ranucci, Gioacchino; Razeto, A.; Reinhold, B.; Renshaw, Andrew; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Sablone, D.; Saggese, P.; Saldanha, R.; Sands, W.; Sangiorgio, Samuele; Savarese, Claudio; Segreto, E.; Semenov, D.; Shields, E.; Singh, Parth; Skorokhvatov, Mikhail; Smirnov, Oleg; Sotnikov, Albert; Stanford, Chris; Suvorov, Yura; Tartaglia, Roberto; Tatarowicz, John; Testera, Gemma; Tonazzo, Alessandra; Trinchese, P.; Unzhakov, Eugenii; Vishneva, Alina; Vogelaar, R. B.; Wada, Masayuki; Walker, Susan E.; Wang, H.; Wang, Y.; Watson, A. W.; Westerdale, S.; Wilhelmi, James; Wojcik, M.; Xiang, Xin; Xu, Jingke; Yang, C. G.; Yoo, J.; Zavatarelli, Sandra; Zec, Adam; Zhong, W. L.; Zhu, Chengliang; Zuzel, G.

    2016-02-01

    DarkSide is a graded experimental project based on radiopure argon, and is now, and will be, used in direct dark matter searches. The present DarkSide-50 detector, operating at the Gran Sasso National Laboratory, is a dual-phase, 50 kg, liquid argon time-projection-chamber surrounded by an active liquid scintillator veto. It is designed to be background free in 3 years of operation. DS-50 performances, when filled with atmospheric argon, are reported. However DS-50 filled with underground argon, shows impressive reduction of the 39Ar isotope. The application of this powerful technology in a future generation of the DarkSide program is discussed.

  7. Kaluza-Klein dark matter

    CERN Document Server

    Cheng, H C; Matchev, K T; Cheng, Hsin-Chia; Feng, Jonathan L; Matchev, Konstantin T.

    2002-01-01

    We propose that cold dark matter is made of Kaluza-Klein particles and explore avenues for its detection. The lightest Kaluza-Klein state is an excellent dark matter candidate if standard model particles propagate in extra dimensions and Kaluza-Klein parity is conserved. We consider Kaluza-Klein gauge bosons. In sharp contrast to the case of supersymmetric dark matter, these annihilate to hard positrons, neutrinos and photons with unsuppressed rates. Direct detection signals are also promising. These conclusions are generic to bosonic dark matter candidates.

  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. Dark matter. A light move

    International Nuclear Information System (INIS)

    Redondo, Javier; Doebrich, Babette

    2013-11-01

    This proceedings contribution reports from the workshop Dark Matter - a light move, held at DESY in Hamburg in June 2013. Dark Matter particle candidates span a huge parameter range. In particular, well motivated candidates exist also in the sub-eV mass region, for example the axion. Whilst a plethora of searches for rather heavy Dark Matter particles exists, there are only very few experiments aimed at direct detection of sub-eV Dark Matter to this date. The aim of our workshop was to discuss if and how this could be changed in the near future.

  10. Dark matter. A light move

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier [Muenchen Univ. (Germany). Arnold Sommerfeld Center; Max-Planck-Institut fuer Physik, Muenchen (Germany); Doebrich, Babette [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-11-15

    This proceedings contribution reports from the workshop Dark Matter - a light move, held at DESY in Hamburg in June 2013. Dark Matter particle candidates span a huge parameter range. In particular, well motivated candidates exist also in the sub-eV mass region, for example the axion. Whilst a plethora of searches for rather heavy Dark Matter particles exists, there are only very few experiments aimed at direct detection of sub-eV Dark Matter to this date. The aim of our workshop was to discuss if and how this could be changed in the near future.

  11. The Dark Energy Camera

    Science.gov (United States)

    Flaugher, B.; Diehl, H. T.; Honscheid, K.; Abbott, T. M. C.; Alvarez, O.; Angstadt, R.; Annis, J. T.; Antonik, M.; Ballester, O.; Beaufore, L.; Bernstein, G. M.; Bernstein, R. A.; Bigelow, B.; Bonati, M.; Boprie, D.; Brooks, D.; Buckley-Geer, E. J.; Campa, J.; Cardiel-Sas, L.; Castander, F. J.; Castilla, J.; Cease, H.; Cela-Ruiz, J. M.; Chappa, S.; Chi, E.; Cooper, C.; da Costa, L. N.; Dede, E.; Derylo, G.; DePoy, D. L.; de Vicente, J.; Doel, P.; Drlica-Wagner, A.; Eiting, J.; Elliott, A. E.; Emes, J.; Estrada, J.; Fausti Neto, A.; Finley, D. A.; Flores, R.; Frieman, J.; Gerdes, D.; Gladders, M. D.; Gregory, B.; Gutierrez, G. R.; Hao, J.; Holland, S. E.; Holm, S.; Huffman, D.; Jackson, C.; James, D. J.; Jonas, M.; Karcher, A.; Karliner, I.; Kent, S.; Kessler, R.; Kozlovsky, M.; Kron, R. G.; Kubik, D.; Kuehn, K.; Kuhlmann, S.; Kuk, K.; Lahav, O.; Lathrop, A.; Lee, J.; Levi, M. E.; Lewis, P.; Li, T. S.; Mandrichenko, I.; Marshall, J. L.; Martinez, G.; Merritt, K. W.; Miquel, R.; Muñoz, F.; Neilsen, E. H.; Nichol, R. C.; Nord, B.; Ogando, R.; Olsen, J.; Palaio, N.; Patton, K.; Peoples, J.; Plazas, A. A.; Rauch, J.; Reil, K.; Rheault, J.-P.; Roe, N. A.; Rogers, H.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schindler, R. H.; Schmidt, R.; Schmitt, R.; Schubnell, M.; Schultz, K.; Schurter, P.; Scott, L.; Serrano, S.; Shaw, T. M.; Smith, R. C.; Soares-Santos, M.; Stefanik, A.; Stuermer, W.; Suchyta, E.; Sypniewski, A.; Tarle, G.; Thaler, J.; Tighe, R.; Tran, C.; Tucker, D.; Walker, A. R.; Wang, G.; Watson, M.; Weaverdyck, C.; Wester, W.; Woods, R.; Yanny, B.; DES Collaboration

    2015-11-01

    The Dark Energy Camera is a new imager with a 2.°2 diameter field of view mounted at the prime focus of the Victor M. Blanco 4 m telescope on Cerro Tololo near La Serena, Chile. The camera was designed and constructed by the Dark Energy Survey Collaboration and meets or exceeds the stringent requirements designed for the wide-field and supernova surveys for which the collaboration uses it. The camera consists of a five-element optical corrector, seven filters, a shutter with a 60 cm aperture, and a charge-coupled device (CCD) focal plane of 250 μm thick fully depleted CCDs cooled inside a vacuum Dewar. The 570 megapixel focal plane comprises 62 2k × 4k CCDs for imaging and 12 2k × 2k CCDs for guiding and focus. The CCDs have 15 μm × 15 μm pixels with a plate scale of 0.″263 pixel-1. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 s with 6-9 electron readout noise. This paper provides a technical description of the camera's engineering, construction, installation, and current status.

  12. Baryonic dark matter

    International Nuclear Information System (INIS)

    Lynden-Bell, D.; Gilmore, G.

    1990-01-01

    Dark matter, first definitely found in the large clusters of galaxies, is now known to be dominant mass in the outer parts of galaxies. All the mass definitely deduced could be made up of baryons, and this would fit well with the requirements of nucleosynthesis in a big bang of small Ω B . However, if inflation is the explanation of the expansion and large scale homogeneity of the universe and of baryon synthesis, and if the universe did not have an infinite extent at the big bang, then Ω should be minutely greater than unity. It is commonly hypothesized that most mass is composed of some unknown, non-baryonic form. This book first discusses the known forms, comets, planets, brown dwarfs, stars, gas, galaxies and Lyman α clouds in which baryons are known to exist. Limits on the amount of dark matter in baryonic form are discussed in the context of the big bang. Inhomogeneities of the right type alleviate the difficulties associated with Ω B = 1 cosmological nucleosynthesis

  13. THE DARK ENERGY CAMERA

    Energy Technology Data Exchange (ETDEWEB)

    Flaugher, B.; Diehl, H. T.; Alvarez, O.; Angstadt, R.; Annis, J. T.; Buckley-Geer, E. J. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Honscheid, K. [Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States); Abbott, T. M. C.; Bonati, M. [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile); Antonik, M.; Brooks, D. [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom); Ballester, O.; Cardiel-Sas, L. [Institut de Física d’Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Beaufore, L. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Bernstein, G. M. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Bernstein, R. A. [Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101 (United States); Bigelow, B.; Boprie, D. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Campa, J. [Centro de Investigaciones Energèticas, Medioambientales y Tecnológicas (CIEMAT), Madrid (Spain); Castander, F. J., E-mail: diehl@fnal.gov [Institut de Ciències de l’Espai, IEEC-CSIC, Campus UAB, Facultat de Ciències, Torre C5 par-2, E-08193 Bellaterra, Barcelona (Spain); Collaboration: DES Collaboration; and others

    2015-11-15

    The Dark Energy Camera is a new imager with a 2.°2 diameter field of view mounted at the prime focus of the Victor M. Blanco 4 m telescope on Cerro Tololo near La Serena, Chile. The camera was designed and constructed by the Dark Energy Survey Collaboration and meets or exceeds the stringent requirements designed for the wide-field and supernova surveys for which the collaboration uses it. The camera consists of a five-element optical corrector, seven filters, a shutter with a 60 cm aperture, and a charge-coupled device (CCD) focal plane of 250 μm thick fully depleted CCDs cooled inside a vacuum Dewar. The 570 megapixel focal plane comprises 62 2k × 4k CCDs for imaging and 12 2k × 2k CCDs for guiding and focus. The CCDs have 15 μm × 15 μm pixels with a plate scale of 0.″263 pixel{sup −1}. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 s with 6–9 electron readout noise. This paper provides a technical description of the camera's engineering, construction, installation, and current status.

  14. Dark Matter remains obscure

    CERN Multimedia

    Fabio Capello

    2011-01-01

    It is one of the hidden secrets that literally surround the Universe. Experiments have shown no result so far because trying to capture particles that do not seem to interact with ordinary matter is no trivial exercise. The OSQAR experiment at CERN is dedicated to the search for axions, one of the candidates for Dark Matter. For its difficult challenge, OSQAR counts on one of the world’s most powerful magnets borrowed from the LHC. In a recent publication, the OSQAR collaboration was able to confirm that no axion signal appears out of the background. In other words: the quest is still on.   The OSQAR experiment installed in the SM18 hall. (Photo by F. Capello) The OSQAR “Light Shining Through a Wall” experiment was officially launched in 2007 with the aim of detecting axions, that is, particles that might be the main components of Dark Matter. OSQAR uses the powerful LHC dipole magnet to intensify the predicted photon-axion conversions in the presence of strong m...

  15. 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

  16. 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.

  17. DarkSUSY: Computing Supersymmetric Dark Matter Properties Numerically

    Energy Technology Data Exchange (ETDEWEB)

    Gondolo, P.

    2004-07-16

    The question of the nature of the dark matter in the Universe remains one of the most outstanding unsolved problems in basic science. One of the best motivated particle physics candidates is the lightest supersymmetric particle, assumed to be the lightest neutralino - a linear combination of the supersymmetric partners of the photon, the Z boson and neutral scalar Higgs particles. Here we describe DarkSUSY, a publicly-available advanced numerical package for neutralino dark matter calculations. In DarkSUSY one can compute the neutralino density in the Universe today using precision methods which include resonances, pair production thresholds and coannihilations. Masses and mixings of supersymmetric particles can be computed within DarkSUSY or with the help of external programs such as FeynHiggs, ISASUGRA and SUSPECT. Accelerator bounds can be checked to identify viable dark matter candidates. DarkSUSY also computes a large variety of astrophysical signals from neutralino dark matter, such as direct detection in low-background counting experiments and indirect detection through antiprotons, antideuterons, gamma-rays and positrons from the Galactic halo or high-energy neutrinos from the center of the Earth or of the Sun. Here we describe the physics behind the package. A detailed manual will be provided with the computer package.

  18. 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.

  19. 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

  20. Residual non-Abelian dark matter and dark radiation

    Directory of Open Access Journals (Sweden)

    P. Ko

    2017-05-01

    Full Text Available We propose a novel particle physics model in which vector dark matter (VDM and dark radiation (DR originate from the same non-Abelian dark sector. We show an illustrating example where dark SU(3 is spontaneously broken into SU(2 subgroup by the nonzero vacuum expectation value (VEV of a complex scalar in fundamental representation of SU(3. The massless gauge bosons associated with the residual unbroken SU(2 constitute DR and help to relieve the tension in Hubble constant measurements between Planck and Hubble Space Telescope. In the meantime, massive dark gauge bosons associated with the broken generators are VDM candidates. Intrinsically, this non-Abelian VDM can interact with non-Abelian DR in the cosmic background, which results in a suppressed matter power spectrum and leads to a smaller σ8 for structure formation.

  1. 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.

  2. Neutrino signals from dark matter

    Science.gov (United States)

    Erkoca, Arif Emre

    Large-scale neutrino telescopes will be powerful tools to observe multitude of mysterious phenomena happening in the Universe. The dark matter puzzle is listed as one of them. In this study, indirect detection of dark matter via neutrino signals is presented. The upward muon, the contained muon and the hadronic shower fluxes are calculated, assuming annihilation/decay of the dark matter in the core of the astrophysical objects and in the Galactic center. Direct neutrino production and secondary neutrino production from the decay of Standard Model particles produced in the annihilation/decay of dark matter are studied. The results are contrasted to the ones previously obtained in the literature, illustrating the importance of properly treating muon propagation and energy loss for the upward muon flux. The dependence of the dark matter signals on the density profile, the dark matter mass and the detector threshold are discussed. Different dark matter models (gravitino, Kaluza-Klein and leptophilic) which can account for recent observations of some indirect searches are analyzed regarding their detection in the kilometer size neutrino detectors in the near future. Muon and shower rates and the minimum observation times in order to reach 2sigma detection significance are evaluated, with the result suggesting that the optimum cone half angles chosen about the Galactic center are about 10° (50°) for the muon (shower) events. A detailed analysis shows that for the annihilating dark matter models such as the leptophilic and Kaluza-Klein models, upward and contained muon as well as showers yield promising signals for dark matter detection in just a few years of observation, whereas for decaying dark matter models, the same observation times can only be reached with showers. The analytical results for the final fluxes are also obtained as well as parametric forms for the muon and shower fluxes for the dark matter models considered in this study.

  3. Exploring a hidden fermionic dark sector

    Indian Academy of Sciences (India)

    2017-10-09

    Oct 9, 2017 ... Fermions in the dark sector also carry a global U ( 1 ) H charge while the gauge bosons and dark scalar do not have any global U ( 1 ) H charge. The lightest fermion in dark sector can serve as a potential dark matter candidate. We investigate whether the proposed dark matter candidate can explain indirect ...

  4. A Light in the Darkness?

    DEFF Research Database (Denmark)

    Brudholm, Thomas

    2007-01-01

    The article considers the implications of how we remember and commemorate so-called "lights in the darkness," such as the rescue of the Jews in Denmark in 1943.......The article considers the implications of how we remember and commemorate so-called "lights in the darkness," such as the rescue of the Jews in Denmark in 1943....

  5. Alternate Models to Dark Energy

    OpenAIRE

    Arun, Kenath; Gudennavar, S B; Prasad, A; Sivaram, C

    2017-01-01

    One of the unresolved questions currently in cosmology is that of the non-linear accelerated expansion of the universe. This has been attributed to the so called Dark Energy (DE). The accelerated expansion of the universe is deduced from measurements of Type Ia supernovae. Here we propose alternate models to account for the Type Ia supernovae measurements without invoking dark energy.

  6. Alternate models to dark energy

    Science.gov (United States)

    Arun, Kenath; Gudennavar, S. B.; Prasad, A.; Sivaram, C.

    2018-01-01

    One of the unresolved questions currently in cosmology is that of the non-linear accelerated expansion of the universe. This has been attributed to the so called Dark Energy (DE). The accelerated expansion of the universe is deduced from measurements of Type Ia supernovae. Here we propose alternate models to account for the Type Ia supernovae measurements without invoking dark energy.

  7. 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 ...

  8. Indirect searches for dark matter

    Indian Academy of Sciences (India)

    Abstract. 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 excite- ments and disappointments that their phenomenological interpretations in terms of almost-standard annihilating dark matter ...

  9. Z2 SIMP dark matter

    International Nuclear Information System (INIS)

    Bernal, Nicolás; Chu, Xiaoyong

    2016-01-01

    Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a Z 2 symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model

  10. Non-baryonic dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Berkes, I.

    1996-12-31

    This article discusses the nature of the dark matter and the possibility of the detection of non-baryonic dark matter in an underground experiment. Among the useful detectors the low temperature bolometers are considered in some detail. (author). 19 refs.

  11. Superheavy dark matter

    CERN Document Server

    Riotto, Antonio

    2000-01-01

    It is usually thought that the present mass density of the Universe is dominated by a weakly interacting massive particle (WIMP), a fossil relic of the early Universe. Theoretical ideas and experimental efforts have focused mostly on production and detection of thermal relics, with mass typically in the range a few GeV to a hundred GeV. Here, we will review scenarios for production of nonthermal dark matter whose mass may be in the range 10/sup 12/ to 10/sup 19/ GeV, much larger than the mass of thermal wimpy WIMPS. We will also review recent related results in understanding the production of very heavy fermions through preheating after inflation. (19 refs).

  12. Dark Slope Streaks

    Science.gov (United States)

    2004-01-01

    13 March 2004 Martian slope streaks occur in the regions most heavily mantled by fine, dry dust, particularly Tharsis, Arabia, and the knobby areas between Amazonis and Cerberus. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some examples of dark slope streaks off of buttes, mesas, and massifs in a dust-mantled crater in central Arabia Terra. New slope streaks form from time to time in the modern martian environment; the streaks in this image probably formed within the past decade. To create them, dust slid or avalanched down the slopes in an almost liquid-like manner. The image is located near 6.8oN, 321.7oW. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  13. Supersymmetric Dark Matter Candidates

    CERN Document Server

    Ellis, John

    2010-01-01

    After reviewing the theoretical, phenomenological and experimental motivations for supersymmetric extensions of the Standard Model, we recall that supersymmetric relics from the Big Bang are expected in models that conserve R parity. We then discuss possible supersymmetric dark matter candidates, focusing on the lightest neutralino and the gravitino. In the latter case, the next-to-lightest supersymmetric particle is expected to be long-lived, and possible candidates include spartners of the tau lepton, top quark and neutrino. We then discuss the roles of the renormalization-group equations and electroweak symmetry breaking in delimiting the supersymmetric parameter space. We discuss in particular the constrained minimal extension of the Standard Model (CMSSM), in which the supersymmetry-breaking parameters are assumed to be universal at the grand unification scale, presenting predictions from a frequentist analysis of its parameter space. We also discuss astrophysical and cosmological constraints on gravitin...

  14. Through a glass, darkly.

    Science.gov (United States)

    Rittenberry, Ronnie

    2005-10-01

    The technology available in today's auto-darkening welding helmets was the stuff of science fiction to welders 30 years ago. A single lens capable of darkening automatically to a variable, preset shade level the instant an arc is struck would have sounded about as realistic as a "Star Trek"-style "transporter" or a cell phone that can take pictures. "It would have been complete and total science fiction," said Kevin Coughlin, president of Hoodlum Welding Gear, Minneapolis. "The technology really didn't exist, so it would be like me telling you your car will be flying in 20 years--you'd look at me and laugh. Even 25 years ago, if someone had told me [the lens] would go from clear to dark when you spark, I'd have said, 'Yeah, right, sure it does.' "

  15. Ultralight particle dark matter

    International Nuclear Information System (INIS)

    Ringwald, A.

    2013-10-01

    We review the physics case for very weakly coupled ultralight particles beyond the Standard Model, in particular for axions and axion-like particles (ALPs): (i) the axionic solution of the strong CP problem and its embedding in well motivated extensions of the Standard Model; (ii) the possibility that the cold dark matter in the Universe is comprised of axions and ALPs; (iii) the ALP explanation of the anomalous transparency of the Universe for TeV photons; and (iv) the axion or ALP explanation of the anomalous energy loss of white dwarfs. Moreover, we present an overview of ongoing and near-future laboratory experiments searching for axions and ALPs: haloscopes, helioscopes, and light-shining-through-a-wall experiments.

  16. Ultralight particle dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Ringwald, A.

    2013-10-15

    We review the physics case for very weakly coupled ultralight particles beyond the Standard Model, in particular for axions and axion-like particles (ALPs): (i) the axionic solution of the strong CP problem and its embedding in well motivated extensions of the Standard Model; (ii) the possibility that the cold dark matter in the Universe is comprised of axions and ALPs; (iii) the ALP explanation of the anomalous transparency of the Universe for TeV photons; and (iv) the axion or ALP explanation of the anomalous energy loss of white dwarfs. Moreover, we present an overview of ongoing and near-future laboratory experiments searching for axions and ALPs: haloscopes, helioscopes, and light-shining-through-a-wall experiments.

  17. Thermalizing Sterile Neutrino Dark Matter

    Science.gov (United States)

    Hansen, Rasmus S. L.; Vogl, Stefan

    2017-12-01

    Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

  18. Thermalizing Sterile Neutrino Dark Matter.

    Science.gov (United States)

    Hansen, Rasmus S L; Vogl, Stefan

    2017-12-22

    Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

  19. 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.

  20. Directly detecting isospin-violating dark matter

    OpenAIRE

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

    2018-01-01

    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–...

  1. Dynamics of teleparallel dark energy

    International Nuclear Information System (INIS)

    Wei Hao

    2012-01-01

    Recently, Geng et al. proposed to allow a non-minimal coupling between quintessence and gravity in the framework of teleparallel gravity, motivated by the similar one in the framework of General Relativity (GR). They found that this non-minimally coupled quintessence in the framework of teleparallel gravity has a richer structure, and named it “teleparallel dark energy”. In the present work, we note that there might be a deep and unknown connection between teleparallel dark energy and Elko spinor dark energy. Motivated by this observation and the previous results of Elko spinor dark energy, we try to study the dynamics of teleparallel dark energy. We find that there exist only some dark-energy-dominated de Sitter attractors. Unfortunately, no scaling attractor has been found, even when we allow the possible interaction between teleparallel dark energy and matter. However, we note that w at the critical points is in agreement with observations (in particular, the fact that w=−1 independently of ξ is a great advantage).

  2. Phenomenology of ELDER dark matter

    Science.gov (United States)

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2017-08-01

    We explore the phenomenology of Elastically Decoupling Relic (ELDER) dark matter. ELDER is a thermal relic whose present density is determined primarily by the cross-section of its elastic scattering off Standard Model (SM) particles. Assuming that this scattering is mediated by a kinetically mixed dark photon, we argue that the ELDER scenario makes robust predictions for electron-recoil direct-detection experiments, as well as for dark photon searches. These predictions are independent of the details of interactions within the dark sector. Together with the closely related Strongly-Interacting Massive Particle (SIMP) scenario, the ELDER predictions provide a physically motivated, well-defined target region, which will be almost entirely accessible to the next generation of searches for sub-GeV dark matter and dark photons. We provide useful analytic approximations for various quantities of interest in the ELDER scenario, and discuss two simple renormalizable toy models which incorporate the required strong number-changing interactions among the ELDERs, as well as explicitly implement the coupling to electrons via the dark photon portal.

  3. 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

  4. Dark matter with a late decaying dark partner

    CERN Document Server

    Fairbairn, Malcolm

    2009-01-01

    We explain the PAMELA positron excess and the PPB-BETS/ATIC e++e− data using a simple two component dark sector model (2CDS). The two particle species in the dark matter sector are assumed to be in thermal equilibrium in the early universe. While one particle is stable and is the present day dark matter, the second one is metastable and decays after the universe is 10−8 s old. In this model it is simple to accommodate the large boost factors required to explain the PAMELA positron excess without the need for large spikes in the local dark matter density. We provide the constraints on the parameters of the model and comment on possible signals at future colliders.

  5. 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.

  6. Cosmological Constraints on Decoupled Dark Photons and Dark Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Joshua [Univ. of Wisconsin, Madison, WI (United States); Jedamzik, Karsten [Univ. Montpellier II (France). Lab. Univers. et Particules de Monpellier; Walker, Devin G.E. [Univ. of Washington, Seattle, WA (United States). Dept. of Physics

    2016-05-23

    Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log ϵ ~ -10 to -17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle ϵ with the Standard Model Higgs is constrained between log ϵ ~ -6 to -15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.

  7. 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

  8. 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

  9. Constraining Dark Matter with ATLAS

    CERN Document Server

    Czodrowski, Patrick; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  10. The Dark Side of Gameplay

    DEFF Research Database (Denmark)

    is an investigation of "dark play" in video games, or game play with controversial themes as well as controversial play behaviour. It covers such questions as: Why do some games stir up political controversies? How do games invite, or even push players towards dark play through their design? Where are the boundaries...... for what can be presented in a games? Are these boundaries different from other media such as film and books, and if so why? What is the allure of dark play and why do players engage in these practices?...

  11. Dark coupling and gauge invariance

    International Nuclear Information System (INIS)

    Gavela, M.B.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

    2010-01-01

    We study a coupled dark energy-dark matter model in which the energy-momentum exchange is proportional to the Hubble expansion rate. The inclusion of its perturbation is required by gauge invariance. We derive the linear perturbation equations for the gauge invariant energy density contrast and velocity of the coupled fluids, and we determine the initial conditions. The latter turn out to be adiabatic for dark energy, when assuming adiabatic initial conditions for all the standard fluids. We perform a full Monte Carlo Markov Chain likelihood analysis of the model, using WMAP 7-year data

  12. Mixed dark matter from technicolor

    DEFF Research Database (Denmark)

    Belyaev, Alexander; T. Frandsen, Mads; Sannino, Francesco

    2011-01-01

    We study natural composite cold dark matter candidates which are pseudo Nambu-Goldstone bosons (pNGB) in models of dynamical electroweak symmetry breaking. Some of these can have a significant thermal relic abundance, while others must be mainly asymmetric dark matter. By considering the thermal...... abundance alone we find a lower bound of MW on the pNGB mass when the (composite) Higgs is heavier than 115 GeV. Being pNGBs, the dark matter candidates are in general light enough to be produced at the LHC....

  13. Capturing prokaryotic dark matter genomes.

    Science.gov (United States)

    Gasc, Cyrielle; Ribière, Céline; Parisot, Nicolas; Beugnot, Réjane; Defois, Clémence; Petit-Biderre, Corinne; Boucher, Delphine; Peyretaillade, Eric; Peyret, Pierre

    2015-12-01

    Prokaryotes are the most diverse and abundant cellular life forms on Earth. Most of them, identified by indirect molecular approaches, belong to microbial dark matter. The advent of metagenomic and single-cell genomic approaches has highlighted the metabolic capabilities of numerous members of this dark matter through genome reconstruction. Thus, linking functions back to the species has revolutionized our understanding of how ecosystem function is sustained by the microbial world. This review will present discoveries acquired through the illumination of prokaryotic dark matter genomes by these innovative approaches. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  14. Dark matter searches at ATLAS

    CERN Document Server

    Gustavino, Giuliano; The ATLAS collaboration

    2016-01-01

    Although the existence of Dark Matter is a well-established hypothesis to explain a range of astrophysical and cosmological measurements, its nature and particle properties still remain one of the greatest unsolved puzzles of particle and astro-particle physics. The collider experiments have developed a comprehensive search program in this sector looking at a wide spectrum of channels in which a Dark Matter evidence can be traced. In this context the last results using the data sample collected at LHC at the new centre-of-mass energy of 13 TeV will be presented giving an outlook of the Dark Matter search status in the ATLAS experiment.

  15. "Dark Matter searches at ATLAS"

    CERN Document Server

    Gustavino, Giuliano; The ATLAS collaboration

    2016-01-01

    Although the existence of Dark Matter is a well-established hypothesis to explain a range of astrophysical and cosmological measurements, its nature and particle properties still remain one of the greatest unsolved puzzles of particle and astro-particle physics. The collider experiments have developed a comprehensive search program in this sector looking at a wide spectrum of channels in which a Dark Matter evidence can be traced. In this context the last results using the data sample collected at LHC at the new centre-of-mass energy of 13 TeV will be presented giving an outlook of the Dark Matter search status in the ATLAS experiment.

  16. General Relativity eliminates Dark Energy, Dark Matter and Universal Expansion

    OpenAIRE

    Bartlett, Rodney

    2018-01-01

    This letter was rejected by International Knowledge Press because "we are unable to conclude that these findings would warrant publication in this journal." The letter is suggesting that dark energy, dark matter and universal expansion are intimately related. However, they aren't viewed as revolutions in cosmology which are essential to a complete understanding of the modern universe. They are instead viewed as properties which need to be added to the cosmos when Einstein...

  17. Dipolar dark matter

    International Nuclear Information System (INIS)

    Masso, Eduard; Mohanty, Subhendra; Rao, Soumya

    2009-01-01

    If dark matter (DM) has nonzero direct or transition, electric or magnetic dipole moment then it can scatter nucleons electromagnetically in direct detection experiments. Using the results from experiments like XENON, CDMS, DAMA, and COGENT, we put bounds on the electric and magnetic dipole moments of DM. If DM consists of Dirac fermions with direct dipole moments, then DM of mass less than 10 GeV is consistent with the DAMA signal and with null results of other experiments. If on the other hand DM consists of Majorana fermions then they can have only nonzero transition moments between different mass eigenstates. We find that Majorana fermions with masses 38 χ < or approx. 100-200 GeV and mass splitting of the order of (150-200) keV can explain the DAMA signal and the null observations from other experiments and in addition give the observed relic density of DM by dipole-mediated annihilation. The absence of the heavier DM state in the present Universe can be explained by dipole-mediated radiative decay. This parameter space for the mass and for dipole moments is allowed by limits from L3 but may have observable signals at LHC.

  18. Imperfect Dark Matter

    Science.gov (United States)

    Mirzagholi, Leila; Vikman, Alexander

    2015-06-01

    We consider cosmology of the recently introduced mimetic matter with higher derivatives (HD). Without HD this system describes irrotational dust—Dark Matter (DM) as we see it on cosmologically large scales. DM particles correspond to the shift-charges—Noether charges of the shifts in the field space. Higher derivative corrections usually describe a deviation from the thermodynamical equilibrium in the relativistic hydrodynamics. Thus we show that mimetic matter with HD corresponds to an imperfect DM which: i) renormalises the Newton's constant in the Friedmann equations, ii) has zero pressure when there is no extra matter in the universe, iii) survives the inflationary expansion which puts the system on a dynamical attractor with a vanishing shift-charge, iv) perfectly tracks any external matter on this attractor, v) can become the main (and possibly the only) source of DM, provided the shift-symmetry in the HD terms is broken during some small time interval in the radiation domination époque. In the second part of the paper we present a hydrodynamical description of general anisotropic and inhomogeneous configurations of the system. This imperfect mimetic fluid has an energy flow in the field's rest frame. We find that in the Eckart and in the Landau-Lifshitz frames the mimetic fluid possesses nonvanishing vorticity appearing already at the first order in the HD. Thus, the structure formation and gravitational collapse should proceed in a rather different fashion from the simple irrotational DM models.

  19. The Other Dark Sky

    Science.gov (United States)

    Pazmino, John

    In previous demonstrations of New York's elimination of luminous graffiti from its skies, I focused attention on large-scale projects in the showcase districts of Manhattan. Although these works earned passionate respect in the dark sky movement, they by the same token were disheartening. New York was in some quarters of the movement regarded more as an unachievable Shangri-La than as a role model to emulate. This presentation focuses on scenes of light abatement efforts in parts of New York which resemble other towns in scale and density. I photographed these scenes along a certain bus route in Brooklyn on my way home from work during October 2001. This route circulates through various "bedroom communities," each similar to a mid-size to large town elsewhere in the United States. The sujbects included individual structures - stores, banks, schools - and streetscapes mimicking downtowns. The latter protrayed a mix of atrocious and excellent lighting practice, being that these streets are in transition by the routine process of replacement and renovation. The fixtures used - box lamps, fluted or Fresnel globes, subdued headsigns, indirect lighting - are casually obtainable by property managers at local outlets for lighting apparatus. They are routinely offered to the property managers by storefront designers, security services, contractors, and the community improvement or betterment councils.

  20. Post flashed darks

    Science.gov (United States)

    Anderson, Jay

    2013-10-01

    The goal of this program is to take the data that will allow a more current calibration for the ACS/WFC CTE correction. We will take data in a similar way that the WFC3/UVIS data are taken so that the same CTE code can be fit to both of them. Currently, the ACS code operates directly on FLT images, but the UVIS code operates on RAW images. Also, the UVIS code is constrained by means of datasets with short-long dark combinations, which allow a careful assessment of CTE losses under low-background conditions.This dataset will allow a similar procedure to be used to constrain the ACS/WFC correction as has been recently used for WFC3/UVIS. WFC3/UFVIS has a similar program this year, and PI-Anderson expects to develop up-to-date calibrations for both at the same time. Once an up-to-date model is constructed, it should be implemented in the pipeline, hopefully for both instruments.

  1. Dark stars in Starobinsky's model

    Science.gov (United States)

    Panotopoulos, Grigoris; Lopes, Ilídio

    2018-01-01

    In the present work we study non-rotating dark stars in f (R ) modified theory of gravity. In particular, we have considered bosonic self-interacting dark matter modeled inside the star as a Bose-Einstein condensate, while as far as the modified theory of gravity is concerned we have assumed Starobinsky's model R +a R2. We solve the generalized structure equations numerically, and we obtain the mass-to-ratio relation for several different values of the parameter a , and for two different dark matter equation-of-states. Our results show that the dark matter stars become more compact in the R-squared gravity compared to general relativity, while at the same time the highest star mass is slightly increased in the modified gravitational theory. The numerical value of the highest star mass for each case has been reported.

  2. Experimental Searches for Dark Matter

    Directory of Open Access Journals (Sweden)

    Sumner Timothy J.

    2002-01-01

    Full Text Available There is now an enormously rich variety of experimental techniques being brought to bear on experimental searches for dark matter, covering a wide range of suggested forms for it. The existence of 'dark matter', in some form or other, is inferred from a number of relatively simple observations and the problem has been known for over half a century. To explain 'dark matter' is one of the foremost challenges today -- the answer will be of fundamental importance to cosmologists, astrophysicists, particle physicists, and general relativists. In this article, I will give a brief review of the observational evidence (concentrating on areas of current significant activity, followed by an equally brief summary of candidate solutions for the 'dark matter'. I will then discuss experimental searches, both direct and indirect. Finally, I will offer prospects for the future.

  3. The Dark Matter of Biology.

    Science.gov (United States)

    Ross, Jennifer L

    2016-09-06

    The inside of the cell is full of important, yet invisible species of molecules and proteins that interact weakly but couple together to have huge and important effects in many biological processes. Such "dark matter" inside cells remains mostly hidden, because our tools were developed to investigate strongly interacting species and folded proteins. Example dark-matter species include intrinsically disordered proteins, posttranslational states, ion species, and rare, transient, and weak interactions undetectable by biochemical assays. The dark matter of biology is likely to have multiple, vital roles to regulate signaling, rates of reactions, water structure and viscosity, crowding, and other cellular activities. We need to create new tools to image, detect, and understand these dark-matter species if we are to truly understand fundamental physical principles of biology. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  4. Direct reconstruction of dark energy.

    Science.gov (United States)

    Clarkson, Chris; Zunckel, Caroline

    2010-05-28

    An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With so few physically motivated models, future dark energy studies cannot only be based on constraining a dark energy parameter space. We present a new nonparametric method which can accurately reconstruct a wide variety of dark energy behavior with no prior assumptions about it. It is simple, quick and relatively accurate, and involves no expensive explorations of parameter space. The technique uses principal component analysis and a combination of information criteria to identify real features in the data, and tailors the fitting functions to pick up trends and smooth over noise. We find that we can constrain a large variety of w(z) models to within 10%-20% at redshifts z≲1 using just SNAP-quality data.

  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. Dark energy from gravitoelectromagnetic inflation?

    International Nuclear Information System (INIS)

    Membiela, A.; Bellini, M.

    2008-01-01

    Gravitoelectromagnetic Inflation (GI) was introduced to describe in a unified manner electromagnetic, gravitatory and inflation fields from a 5D vacuum state. On the other hand, the primordial origin and evolution of dark energy is today unknown. In this letter we show using GI that the zero modes of some redefined vector fields B i = A i /a produced during inflation could be the source of dark energy in the Universe.

  7. Dark matter triggers of supernovae

    Science.gov (United States)

    Graham, Peter W.; Rajendran, Surjeet; Varela, Jaime

    2015-09-01

    The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to 1.25 M⊙ rules out primordial black holes with masses ˜1019- 1020 gm as a dominant constituent of the local dark matter density. Black holes with masses as large as 1024 gm will be excluded if recent observations by the NuStar Collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range 1020- 1022 gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large spacetime volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.

  8. A History of Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Gianfranco [U. Amsterdam, GRAPPA; Hooper, Dan [Fermilab

    2016-05-16

    Although dark matter is a central element of modern cosmology, the history of how it became accepted as part of the dominant paradigm is often ignored or condensed into a brief anecdotical account focused around the work of a few pioneering scientists. The aim of this review is to provide the reader with a broader historical perspective on the observational discoveries and the theoretical arguments that led the scientific community to adopt dark matter as an essential part of the standard cosmological model.

  9. Decoupling dark energy from matter

    Science.gov (United States)

    Brax, Philippe; van de Bruck, Carsten; Davis, Anne-Christine; Martin, Jérôme

    2009-09-01

    We examine the embedding of dark energy in high energy models based upon supergravity and extend the usual phenomenological setting comprising an observable sector and a hidden supersymmetry breaking sector by including a third sector leading to the acceleration of the expansion of the universe. We find that gravitational constraints on the non-existence of a fifth force naturally imply that the dark energy sector must possess an approximate shift symmetry. When exact, the shift symmetry provides an example of a dark energy sector with a runaway potential and a nearly massless dark energy field whose coupling to matter is very weak, contrary to the usual lore that dark energy fields must couple strongly to matter and lead to gravitational inconsistencies. Moreover, the shape of the potential is stable under one-loop radiative corrections. When the shift symmetry is slightly broken by higher order terms in the Kähler potential, the coupling to matter remains small. However, the cosmological dynamics are largely affected by the shift symmetry breaking operators leading to the appearance of a minimum of the scalar potential such that dark energy behaves like an effective cosmological constant from very early on in the history of the universe.

  10. 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.

  11. Direct detection with dark mediators

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, David; Surujon, Ze' ev [C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794 (United States); Tsai, Yuhsin [Physics Department, University of California Davis, Davis, CA 95616 (United States)

    2014-11-10

    We introduce dark mediator Dark Matter (dmDM) where the dark and visible sectors are connected by at least one light mediator ϕ carrying the same dark charge that stabilizes DM. ϕ is coupled to the Standard Model via an operator q{sup ¯}qϕϕ{sup ⁎}/Λ, and to dark matter via a Yukawa coupling y{sub χ}χ{sup c¯}χϕ. Direct detection is realized as the 2→3 process χN→χ{sup ¯}Nϕ at tree-level for m{sub ϕ}≲10 keV and small Yukawa coupling, or alternatively as a loop-induced 2→2 process χN→χN. We explore the direct-detection consequences of this scenario and find that a heavy O(100 GeV) dmDM candidate fakes different O(10 GeV) standard WIMPs in different experiments. Large portions of the dmDM parameter space are detectable above the irreducible neutrino background and not yet excluded by any bounds. Interestingly, for the m{sub ϕ} range leading to novel direct detection phenomenology, dmDM is also a form of Self-Interacting Dark Matter (SIDM), which resolves inconsistencies between dwarf galaxy observations and numerical simulations.

  12. Dark matter and global symmetries

    Directory of Open Access Journals (Sweden)

    Yann Mambrini

    2016-09-01

    Full Text Available General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left–Right, Singlet Fermionic, Zee–Babu, 3-3-1 and Radiative See-Saw models. Assuming that (i global symmetries are broken at the Planck scale, that (ii the non-renormalizable operators mediating dark matter decay have O(1 couplings, that (iii the dark matter is a singlet field, and that (iv the dark matter density distribution is well described by a NFW profile, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV–TeV, including the WIMP regime.

  13. Dark matter beams at LBNF

    Energy Technology Data Exchange (ETDEWEB)

    Coloma, Pilar; Dobrescu, Bogdan A.; Frugiuele, Claudia; Harnik, Roni [Theory Department, Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL 60510 (United States)

    2016-04-08

    High-intensity neutrino beam facilities may produce a beam of light dark matter when protons strike the target. Searches for such a dark matter beam using its scattering in a nearby detector must overcome the large neutrino background. We characterize the spatial and energy distributions of the dark matter and neutrino beams, focusing on their differences to enhance the sensitivity to dark matter. We find that a dark matter beam produced by a Z{sup ′} boson in the GeV mass range is both broader and more energetic than the neutrino beam. The reach for dark matter is maximized for a detector sensitive to hard neutral-current scatterings, placed at a sizable angle off the neutrino beam axis. In the case of the Long-Baseline Neutrino Facility (LBNF), a detector placed at roughly 6 degrees off axis and at a distance of about 200 m from the target would be sensitive to Z{sup ′} couplings as low as 0.05. This search can proceed symbiotically with neutrino measurements. We also show that the MiniBooNE and MicroBooNE detectors, which are on Fermilab’s Booster beamline, happen to be at an optimal angle from the NuMI beam and could perform searches with existing data. This illustrates potential synergies between LBNF and the short-baseline neutrino program if the detectors are positioned appropriately.

  14. 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.

  15. Forbidden Channels and SIMP Dark Matter

    OpenAIRE

    Choi Soo-Min; Kang Yoo-Jin; Lee Hyun Min

    2018-01-01

    In this review, we focus on dark matter production from thermal freeze-out with forbidden channels and SIMP processes. We show that forbidden channels can be dominant to produce dark matter depending on the dark photon and / or dark Higgs mass compared to SIMP.

  16. Studying dark matter haloes with weak lensing

    NARCIS (Netherlands)

    Velander, Malin Barbro Margareta

    2012-01-01

    Our Universe is comprised not only of normal matter but also of unknown components: dark matter and dark energy. This Thesis recounts studies of dark matter haloes, using a technique known as weak gravitational lensing, in order to learn more about the nature of these dark components. The haloes

  17. The relevance of Very Light Dark Matter

    OpenAIRE

    Yajnik Urjit A.

    2014-01-01

    A concordant model of Dark Matter and Dark Energy is presented. Dark Energy arises out of magnetic condensation of very light fermions of micro-eV mass charged under an unbroken gauge group U(1)X. The Dark Matter candidate is an oppositely charged fermionic species which is then shown to be naturally in the MeV to keV range.

  18. NASA's Dark Matter and Dark Energy Programs

    Energy Technology Data Exchange (ETDEWEB)

    Gehrels, N.; Cannizzo, J.K.

    2013-10-15

    We present an overview of selected high value scientific results and prospects for future advances from NASA's “Dark” missions, i.e., those covering dark matter (DM) and dark energy (DE). This includes current missions HST, Chandra, Swift, GALEX, Suzaku, Fermi, and future missions JWST and WFIRST. These missions and earlier ones, such as WMAP, have brought about a revolution in our understanding of the fundamental properties of the universe – its age, rate of expansion, deceleration history, and composition (i.e., relative mix of luminous matter, dark matter, and dark energy). The next chapters in this story will be written by JWST and WFIRST. JWST was the highest priority of the 2000 Decadal Survey. It will observe in the near and medium infrared, and revolutionize our understanding of the high redshift universe. WFIRST is the highest ranked large space mission of the 2010 Decadal Survey. It is a NASA observatory designed to perform wide-field imaging and slitless spectroscopic surveys of the NIR sky (0.7 – 2.5μ). WFIRST will: (i) measure the expansion history of the universe, and thereby constrain dark energy, (ii) find Earth-like planets around other stars using microlensing, and (iii) perform surveys that are ∼100 times more sensitive than current NIR surveys.

  19. Probing the Dark Sector with Dark Matter Bound States.

    Science.gov (United States)

    An, Haipeng; Echenard, Bertrand; Pospelov, Maxim; Zhang, Yue

    2016-04-15

    A model of the dark sector where O(few  GeV) mass dark matter particles χ couple to a lighter dark force mediator V, m_{V}≪m_{χ}, is motivated by the recently discovered mismatch between simulated and observed shapes of galactic halos. Such models, in general, provide a challenge for direct detection efforts and collider searches. We show that for a large range of coupling constants and masses, the production and decay of the bound states of χ, such as 0^{-+} and 1^{--} states, η_{D} and ϒ_{D}, is an important search channel. We show that e^{+}e^{-}→η_{D}+V or ϒ_{D}+γ production at B factories for α_{D}>0.1 is sufficiently strong to result in multiple pairs of charged leptons and pions via η_{D}→2V→2(l^{+}l^{-}) and ϒ_{D}→3V→3(l^{+}l^{-}) (l=e,μ,π). The absence of such final states in the existing searches performed at BABAR and Belle sets new constraints on the parameter space of the model. We also show that a search for multiple bremsstrahlung of dark force mediators, e^{+}e^{-}→χχ[over ¯]+nV, resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter.

  20. Blood Types

    Science.gov (United States)

    ... Drive Home Types of Blood Donations Blood Types Blood Types Not all blood is alike. There are eight ... African descent. Learn More About Blood and Diversity Blood Types and Transfusion There are very specific ways in ...

  1. 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

  2. Parity Violation by a Dark Gauge Boson

    CERN Document Server

    Lee, Hye-Sung

    2014-01-01

    We overview the dark parity violation, which means the parity violation induced by a dark gauge boson of very small mass and coupling. When a dark gauge boson has an axial coupling, as in dark Z model, it can change the effective Weinberg angle in the low-energy experiments such as the atomic parity violation and the low-Q^2 polarized electron scatterings. Such low-energy parity tests are an excellent probe of the dark force.

  3. 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.

  4. Understanding Dark Energy

    Science.gov (United States)

    Greyber, Howard

    2009-11-01

    By careful analysis of the data from the WMAP satellite, scientists were surprised to determine that about 70% of the matter in our universe is in some unknown form, and labeled it Dark Energy. Earlier, in 1998, two separate international groups of astronomers studying Ia supernovae were even more surprised to be forced to conclude that an amazing smooth transition occurred, from the expected slowing down of the expansion of our universe (due to normal positive gravitation) to an accelerating expansion of the universe that began at at a big bang age of the universe of about nine billion years. In 1918 Albert Einstein stated that his Lambda term in his theory of general relativity was ees,``the energy of empty space,'' and represented a negative pressure and thus a negative gravity force. However my 2004 ``Strong'' Magnetic Field model (SMF) for the origin of magnetic fields at Combination Time (Astro-ph0509223 and 0509222) in our big bang universe produces a unique topology for Superclusters, having almost all the mass, visible and invisible, i.e. from clusters of galaxies down to particles with mass, on the surface of an ellipsoid surrounding a growing very high vacuum. If I hypothesize, with Einstein, that there exists a constant ees force per unit volume, then, gradually, as the universe expands from Combination Time, two effects occur (a) the volume of the central high vacuum region increases, and (b) the density of positive gravity particles in the central region of each Supercluster in our universe decreases dramatically. Thus eventually Einstein's general relativity theory's repulsive gravity of the central very high vacuum region becomes larger than the positive gravitational attraction of all the clusters of galaxies, galaxies, quasars, stars and plasma on the Supercluster shell, and the observed accelerating expansion of our universe occurs. This assumes that our universe is made up mostly of such Superclusters. It is conceivable that the high vacuum

  5. Cosmic Dark Radiation and Neutrinos

    Directory of Open Access Journals (Sweden)

    Maria Archidiacono

    2013-01-01

    Full Text Available New measurements of the cosmic microwave background (CMB by the Planck mission have greatly increased our knowledge about the universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our cosmological model which is testable by Planck and other observational probes. At the moment, the possible existence of dark radiation is an unsolved question. For instance, the discrepancy between the value of the Hubble constant, H0, inferred from the Planck data and local measurements of H0 can to some extent be alleviated by enlarging the minimal ΛCDM model to include additional relativistic degrees of freedom. From a fundamental physics point of view, dark radiation is no less interesting. Indeed, it could well be one of the most accessible windows to physics beyond the standard model, for example, sterile neutrinos. Here, we review the most recent cosmological results including a complete investigation of the dark radiation sector in order to provide an overview of models that are still compatible with new cosmological observations. Furthermore, we update the cosmological constraints on neutrino physics and dark radiation properties focusing on tensions between data sets and degeneracies among parameters that can degrade our information or mimic the existence of extra species.

  6. The search for dark matter

    International Nuclear Information System (INIS)

    Smith, Nigel; Spooner, Neil

    2000-01-01

    Experiments housed deep underground are searching for new particles that could simultaneously solve one of the biggest mysteries in astrophysics and reveal what lies beyond the Standard Model of particle physics. Physicists are very particular about balancing budgets. Energy, charge and momentum all have to be conserved and often money as well. Astronomers were therefore surprised and disturbed to learn in the 1930s that our own Milky Way galaxy behaved as if it contained more matter than could be seen with telescopes. This puzzling non-luminous matter became known as ''dark matter'' and we now know that over 90% of the matter in the entire universe is dark. In later decades the search for this dark matter shifted from the heavens to the Earth. In fact, the search for dark matter went underground. Today there are experiments searching for dark matter hundreds and thousands of metres below ground in mines, road tunnels and other subterranean locations. These experiments are becoming more sensitive every year and are beginning to test various new models and theories in particle physics and cosmology. (UK)

  7. Euclid and the Dark Universe

    Science.gov (United States)

    Mellier, Yannick

    2016-07-01

    The ESA Euclid mission aims to understand why the expansion of the Universe is accelerating and pin down the source responsible for the acceleration. It will uncover the very nature of dark energy and gravitation by measuring with exquisite accuracy the expansion rate of the Universe and the growth rate of structure formation in the Universe. To achieve its objectives Euclid will observe the distribution of dark matter in the Universe by measuring shapes of weakly distorted distant galaxies lensed by foreground cosmic structures with the VIS imaging instrument. In parallel, Euclid will analyse the clustering of galaxies and the distribution of clusters of galaxies by using spectroscopy and measuring redshifts of galaxies with the NISP photometer and spectrometer instrument. The Euclid mission will observe one third of the sky (15,000 deg2) to collect data on several billion galaxies spread over the last ten billion years. In this presentation I will report on the considerable technical and scientific progresses made since COSPAR 2014, on behalf of the Euclid Collaboration. The recent mission PDR that has been passed successfully shows that Euclid should meet its requirements and achieve its primary scientific objectives to map the dark universe. The most recent forecasts and constraints on dark energy, gravity, dark matter and inflation will be presented.

  8. Dark Energy and Spacetime Symmetry

    Directory of Open Access Journals (Sweden)

    Irina Dymnikova

    2017-03-01

    Full Text Available The Petrov classification of stress-energy tensors provides a model-independent definition of a vacuum by the algebraic structure of its stress-energy tensor and implies the existence of vacua whose symmetry is reduced as compared with the maximally symmetric de Sitter vacuum associated with the Einstein cosmological term. This allows to describe a vacuum in general setting by dynamical vacuum dark fluid, presented by a variable cosmological term with the reduced symmetry which makes vacuum fluid essentially anisotropic and allows it to be evolving and clustering. The relevant solutions to the Einstein equations describe regular cosmological models with time-evolving and spatially inhomogeneous vacuum dark energy, and compact vacuum objects generically related to a dark energy: regular black holes, their remnants and self-gravitating vacuum solitons with de Sitter vacuum interiors—which can be responsible for observational effects typically related to a dark matter. The mass of objects with de Sitter interior is generically related to vacuum dark energy and to breaking of space-time symmetry. In the cosmological context spacetime symmetry provides a mechanism for relaxing cosmological constant to a needed non-zero value.

  9. Dark Skies Rangers - Fighting light pollution and simulating dark skies

    Science.gov (United States)

    Doran, Rosa; Correia, Nelson; Guerra, Rita; Costa, Ana

    2015-03-01

    Dark Skies Rangers is an awareness program aimed at students of all ages to stimulate them to make an audit of light pollution in their school/district. The young light pollution fighters evaluate the level of light pollution, how much energy is being wasted, and produce a report to be delivered to the local authorities. They are also advised to promote a light pollution awareness campaign to the local community targeting not only the dark skies but also other implications such as effects in our health, to the flora and fauna, etc.

  10. Bouncing Cosmologies with Dark Matter and Dark Energy

    Directory of Open Access Journals (Sweden)

    Yi-Fu Cai

    2016-12-01

    Full Text Available We review matter bounce scenarios where the matter content is dark matter and dark energy. These cosmologies predict a nearly scale-invariant power spectrum with a slightly red tilt for scalar perturbations and a small tensor-to-scalar ratio. Importantly, these models predict a positive running of the scalar index, contrary to the predictions of the simplest inflationary and ekpyrotic models, and hence, could potentially be falsified by future observations. We also review how bouncing cosmological space-times can arise in theories where either the Einstein equations are modified or where matter fields that violate the null energy condition are included.

  11. 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.)

  12. Dark Energy and Dark Matter from Emergent Gravity Picture

    OpenAIRE

    Seok Yang Hyun

    2018-01-01

    We suggest that dark energy and dark matter may be a cosmic uroboros of quantum gravity due to the coherent vacuum structure of spacetime. We apply the emergent gravity to a large N matrix model by considering the vacuum in the noncommutative (NC) Coulomb branch satisfying the Heisenberg algebra. We observe that UV fluctuations in the NC Coulomb branch are always paired with IR fluctuations and these UV/IR fluctuations can be extended to macroscopic scales. We show that space-like fluctuation...

  13. Multiscatter stellar capture of dark matter

    Science.gov (United States)

    Bramante, Joseph; Delgado, Antonio; Martin, Adam

    2017-09-01

    Dark matter may be discovered through its capture in stars and subsequent annihilation. It is usually assumed that dark matter is captured after a single scattering event in the star; however this assumption breaks down for heavy dark matter, which requires multiple collisions with the star to lose enough kinetic energy to become captured. We analytically compute how multiple scatters alter the capture rate of dark matter and identify the parameter space where the effect is largest. Using these results, we then show how multiscatter capture of dark matter on compact stars can be used to probe heavy mX≫TeV dark matter with remarkably small dark matter-nucleon scattering cross sections. As one example, it is demonstrated how measuring the temperature of old neutron stars in the Milky Way's center provides sensitivity to high mass dark matter with dark matter-nucleon scattering cross sections smaller than the xenon direct detection neutrino floor.

  14. Dark Matter searches at ATLAS

    CERN Document Server

    Cortes-Gonzalez, Arely; The ATLAS collaboration

    2016-01-01

    If Dark Matter interacts weakly with the Standard Model it can be produced at the LHC. It can be identified via initial state radiation (ISR) of the incoming partons, leaving a signature in the detector of the ISR particle (jet, photon, Z or W) recoiling off of the invisible Dark Matter particles, resulting in a large momentum imbalance. Many signatures of large missing transverse momentum recoiling against jets, photons, heavy-flavor quarks, weak gauge bosons or Higgs bosons provide an interesting channel for Dark Matter searches. These LHC searches complement those from (in)direct detection experiments. Results of these searches with the ATLAS experiment, in both effective field theory and simplified models with pair WIMP production are discussed. Both 8TeV and 13TeV pp collision data has been used in these results.

  15. Laying bare Venus' dark secrets

    International Nuclear Information System (INIS)

    Allen, D.A.

    1987-01-01

    Ground-based IR observations of the dark side of Venus obtained in 1983 and 1985 with the Anglo-Australian Telescope are studied. An IR spectrum of Venus' dark side is analyzed. It is observed that the Venus atmosphere is composed of CO and radiation escapes only at 1.74 microns and 2.2 to 2.4 microns. The possible origin of the radiation, either due to absorbed sunlight or escaping thermal radiation, was investigated. These two hypotheses were eliminated, and it is proposed that the clouds of Venus are transparent and the radiation originates from the same stratum as the brighter portions but is weakened by the passage through the upper layer. The significance of the observed dark side markings is discussed

  16. The dark side of curvature

    International Nuclear Information System (INIS)

    Barenboim, Gabriela; Martínez, Enrique Fernández; Mena, Olga; Verde, Licia

    2010-01-01

    Geometrical tests such as the combination of the Hubble parameter H(z) and the angular diameter distance d A (z) can, in principle, break the degeneracy between the dark energy equation of state parameter w(z), and the spatial curvature Ω k in a direct, model-independent way. In practice, constraints on these quantities achievable from realistic experiments, such as those to be provided by Baryon Acoustic Oscillation (BAO) galaxy surveys in combination with CMB data, can resolve the cosmic confusion between the dark energy equation of state parameter and curvature only statistically and within a parameterized model for w(z). Combining measurements of both H(z) and d A (z) up to sufficiently high redshifts z ∼ 2 and employing a parameterization of the redshift evolution of the dark energy equation of state are the keys to resolve the w(z)−Ω k degeneracy

  17. Dark matter in the universe

    CERN Document Server

    Seigar, Marc S

    2015-01-01

    The study of dark matter, in both astrophysics and particle physics, has emerged as one of the most active and exciting topics of research in recent years. This book reviews the history behind the discovery of missing mass (or unseen mass) in the universe, and ties this into the proposed extensions to the Standard Model of Particle Physics (such as Supersymmetry), which were being proposed within the same time frame. This book is written as an introduction to these problems at the forefront of astrophysics and particle physics, with the goal of conveying the physics of dark matter to beginning undergraduate majors in scientific fields. The book goes on to describe existing and upcoming experiments and techniques, which will be used to detect dark matter either directly or indirectly.

  18. 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.

  19. The DAMIC Dark Matter Experiment

    Energy Technology Data Exchange (ETDEWEB)

    de Mello Neto, J. R.T. [Federal Univ. of Rio de Janeiro (Brazil). et al

    2015-10-07

    The DAMIC (DArk Matter In CCDs) experiment uses high-resistivity, scientific-grade CCDs to search for dark matter. The CCD’s low electronic noise allows an unprecedently low energy threshold of a few tens of eV; this characteristic makes it possible to detect silicon recoils resulting from interactions of low-mass WIMPs. In addition, the CCD’s high spatial resolution and the excellent energy response results in very effective background identification techniques. The experiment has a unique sensitivity to dark matter particles with masses below 10 GeV/c2. Previous results have motivated the construction of DAMIC100, a 100 grams silicon target detector currently being installed at SNOLAB. The mode of operation and unique imaging capabilities of the CCDs, and how they may be exploited to characterize and suppress backgrounds are discussed, as well as physics results after one year of data taking.

  20. Flavoured Dark Matter moving left

    Science.gov (United States)

    Blanke, Monika; Das, Satrajit; Kast, Simon

    2018-02-01

    We investigate the phenomenology of a simplified model of flavoured Dark Matter (DM), with a dark fermionic flavour triplet coupling to the left-handed SU(2) L quark doublets via a scalar mediator. The DM-quark coupling matrix is assumed to constitute the only new source of flavour and CP violation, following the hypothesis of Dark Minimal Flavour Violation. We analyse the constraints from LHC searches, from meson mixing data in the K, D, and B d,s meson systems, from thermal DM freeze-out, and from direct detection experiments. Our combined analysis shows that while the experimental constraints are similar to the DMFV models with DM coupling to right-handed quarks, the multitude of couplings between DM and the SM quark sector resulting from the SU(2) L structure implies a richer phenomenology and significantly alters the resulting impact on the viable parameter space.

  1. The Logotropic Dark Fluid as a unification of dark matter and dark energy

    Directory of Open Access Journals (Sweden)

    Pierre-Henri Chavanis

    2016-07-01

    Full Text Available We propose a heuristic unification of dark matter and dark energy in terms of a single “dark fluid” with a logotropic equation of state P=Aln⁡(ρ/ρP, where ρ is the rest-mass density, ρP=5.16×1099gm−3 is the Planck density, and A is the logotropic temperature. The energy density ϵ is the sum of a rest-mass energy term ρc2∝a−3 mimicking dark matter and an internal energy term u(ρ=−P(ρ−A=3Aln⁡a+C mimicking dark energy (a is the scale factor. The logotropic temperature is approximately given by A≃ρΛc2/ln⁡(ρP/ρΛ≃ρΛc2/[123ln⁡(10], where ρΛ=6.72×10−24gm−3 is the cosmological density and 123 is the famous number appearing in the ratio ρP/ρΛ∼10123 between the Planck density and the cosmological density. More precisely, we obtain A=2.13×10−9gm−1s−2 that we interpret as a fundamental constant. At the cosmological scale, our model fulfills the same observational constraints as the ΛCDM model (they will differ in about 25 Gyrs when the logotropic universe becomes phantom. However, the logotropic dark fluid has a nonzero speed of sound and a nonzero Jeans length which, at the beginning of the matter era, is about λJ=40.4pc, in agreement with the minimum size of the dark matter halos observed in the universe. The existence of a nonzero Jeans length may solve the missing satellite problem. At the galactic scale, the logotropic pressure balances the gravitational attraction, providing halo cores instead of cusps. This may solve the cusp problem. The logotropic equation of state generates a universal rotation curve that agrees with the empirical Burkert profile of dark matter halos up to the halo radius. In addition, it implies that all the dark matter halos have the same surface density Σ0=ρ0rh=141M⊙/pc2 and that the mass of dwarf galaxies enclosed within a sphere of fixed radius ru=300pc has the same value M300=1.93×107M⊙, in remarkable agreement with the observations [Donato et al. [10

  2. Dark Matter Searches at ATLAS

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The astrophysical evidence of dark matter provides some of the most compelling clues to the nature of physics beyond the Standard Model. From these clues, ATLAS has developed a broad and systematic search program for dark matter production in LHC collisions. These searches are now entering their prime, with the LHC now colliding protons at the increased 13 TeV centre-of-mass energy and set to deliver much larger datasets than ever before. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  3. Dark patterns in proxemic interactions

    DEFF Research Database (Denmark)

    Greenberg, Saul; Boring, Sebastian; Vermeulen, Jo

    2014-01-01

    to better facilitate seamless and natural interactions. To do so, both people and devices are tracked to determine their spatial relationships. While interest in proxemic interactions has increased over the last few years, it also has a dark side: knowledge of proxemics may (and likely will) be easily...... exploited to the detriment of the user. In this paper, we offer a critical perspective on proxemic interactions in the form of dark patterns: ways proxemic interactions can be misused. We discuss a series of these patterns and describe how they apply to these types of interactions. In addition, we identify...

  4. Dark Valley in Newton Crater

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-418, 11 July 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image shows part of a dark-floored valley system in northern Newton Crater. The valley might have been originally formed by liquid water; the dark material is probably sand that has blown into the valley in more recent times. The picture was acquired earlier this week on July 6, 2003, and is located near 39.2oS, 157.9oW. The picture covers an area 2.3 km (1.4 mi) across; sunlight illuminates the scene from the upper left.

  5. 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....

  6. Dark energy from quantum matter

    International Nuclear Information System (INIS)

    Dappiaggi, Claudio; Hack, Thomas-Paul; Moeller, Jan; Pinamonti, Nicola

    2010-07-01

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the CDM model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations. (orig.)

  7. Dark matter in elliptical galaxies

    Science.gov (United States)

    Carollo, C. M.; Zeeuw, P. T. DE; Marel, R. P. Van Der; Danziger, I. J.; Qian, E. E.

    1995-01-01

    We present measurements of the shape of the stellar line-of-sight velocity distribution out to two effective radii along the major axes of the four elliptical galaxies NGC 2434, 2663, 3706, and 5018. The velocity dispersion profiles are flat or decline gently with radius. We compare the data to the predictions of f = f(E, L(sub z)) axisymmetric models with and without dark matter. Strong tangential anisotropy is ruled out at large radii. We conclude from our measurements that massive dark halos must be present in three of the four galaxies, while for the fourth galaxy (NGC 2663) the case is inconclusive.

  8. Dark energy from quantum matter

    Energy Technology Data Exchange (ETDEWEB)

    Dappiaggi, Claudio; Hack, Thomas-Paul [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Moeller, Jan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Pinamonti, Nicola [Rome-2 Univ. (Italy). Dipt. di Matematica

    2010-07-15

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the CDM model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations. (orig.)

  9. Dark Energy and Dark Matter from Emergent Gravity Picture

    Directory of Open Access Journals (Sweden)

    Seok Yang Hyun

    2018-01-01

    Full Text Available We suggest that dark energy and dark matter may be a cosmic uroboros of quantum gravity due to the coherent vacuum structure of spacetime. We apply the emergent gravity to a large N matrix model by considering the vacuum in the noncommutative (NC Coulomb branch satisfying the Heisenberg algebra. We observe that UV fluctuations in the NC Coulomb branch are always paired with IR fluctuations and these UV/IR fluctuations can be extended to macroscopic scales. We show that space-like fluctuations give rise to the repulsive gravitational force while time-like fluctuations generate the attractive gravitational force. When considering the fact that the fluctuations are random in nature and we are living in the (3+1-dimensional spacetime, the ratio of the repulsive and attractive components will end in ¾ : ¼= 75 : 25 and this ratio curiously coincides with the dark composition of our current Universe. If one includes ordinary matters which act as the attractive gravitational force, the emergent gravity may explain the dark sector of our Universe more precisely.

  10. Dark Energy and Dark Matter from Emergent Gravity Picture

    Science.gov (United States)

    Seok Yang, Hyun

    2018-01-01

    We suggest that dark energy and dark matter may be a cosmic uroboros of quantum gravity due to the coherent vacuum structure of spacetime. We apply the emergent gravity to a large N matrix model by considering the vacuum in the noncommutative (NC) Coulomb branch satisfying the Heisenberg algebra. We observe that UV fluctuations in the NC Coulomb branch are always paired with IR fluctuations and these UV/IR fluctuations can be extended to macroscopic scales. We show that space-like fluctuations give rise to the repulsive gravitational force while time-like fluctuations generate the attractive gravitational force. When considering the fact that the fluctuations are random in nature and we are living in the (3+1)-dimensional spacetime, the ratio of the repulsive and attractive components will end in ¾ : ¼= 75 : 25 and this ratio curiously coincides with the dark composition of our current Universe. If one includes ordinary matters which act as the attractive gravitational force, the emergent gravity may explain the dark sector of our Universe more precisely.

  11. Interacting dark sector with transversal interaction

    Energy Technology Data Exchange (ETDEWEB)

    Chimento, Luis P.; Richarte, Martín G. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires 1428 (Argentina)

    2015-03-26

    We investigate the interacting dark sector composed of dark matter, dark energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker (FRW) background by introducing a three-dimensional internal space spanned by the interaction vector Q and solve the source equation for a linear transversal interaction. Then, we explore a realistic model with dark matter coupled to a scalar field plus a decoupled radiation term, analyze the amount of dark energy in the radiation era and find that our model is consistent with the recent measurements of cosmic microwave background anisotropy coming from Planck along with the future constraints achievable by CMBPol experiment.

  12. Blood Tests

    Science.gov (United States)

    ... your blood, as discussed in the following paragraphs. Red Blood Cells Red blood cells carry oxygen from ... leaks out, and its levels in your blood rise. For example, blood levels of troponin rise when ...

  13. Oxygen saturation in human retinal vessels is higher in dark than in light.

    Science.gov (United States)

    Hardarson, Sveinn Hakon; Basit, Samy; Jonsdottir, Thora Elisabet; Eysteinsson, Thor; Halldorsson, Gisli Hreinn; Karlsson, Robert Arnar; Beach, James Melvin; Benediktsson, Jon Atli; Stefansson, Einar

    2009-05-01

    Animal studies have indicated that retinal oxygen consumption is greater in dark than light. In this study, oxygen saturation is measured in retinal vessels of healthy humans during dark and light. The oximeter consists of a fundus camera, a beam splitter, a digital camera and software, which calculates hemoglobin oxygen saturation in the retinal vessels. In the first experiment, 18 healthy individuals underwent oximetry measurements after 30 minutes in the dark, followed by alternating 5-minute periods of white light (80 cd/m(2)) and dark. In the second experiment, 23 volunteers underwent oximetry measurements after 30 minutes in the dark, followed by light at 1, 10, and 100 cd/m(2). Three subjects were excluded from analysis in the first experiment and four in the second experiment because of poor image quality. In the first experiment, the arteriolar saturation decreased from 92% +/- 4% (n = 15; mean +/- SD) after 30 minutes in the dark to 89% +/- 5% after 5 minutes in the light (P = 0.008). Corresponding numbers for venules are 60% +/- 5% in the dark and 55% +/- 10% (P = 0.020) in the light. In the second experiment, the arteriolar saturation was 92% +/- 4% in the dark and 88% +/- 7% in 100 cd/m(2) light (n = 19, P = 0.012). The corresponding values for venules were 59% +/- 9% in the dark and 55% +/- 10% in 100 cd/m(2) light (P = 0.065). Oxygen saturation in retinal blood vessels is higher in dark than in 80 or 100 cd/m(2) light in human retinal arterioles and venules. The authors propose that this is a consequence of increased oxygen demand in the outer retina in the dark.

  14. Non--Baryonic Dark Matter

    OpenAIRE

    Berezinsky, V.; Bottino, A.; Mignola, G.

    1996-01-01

    The best particle candidates for non--baryonic cold dark matter are reviewed, namely, neutralino, axion, axino and Majoron. These particles are considered in the context of cosmological models with the restrictions given by the observed mass spectrum of large scale structures, data on clusters of galaxies, age of the Universe etc.

  15. The dark side of matter

    International Nuclear Information System (INIS)

    Cline, D.

    2003-01-01

    The number of baryons (protons and neutrons) of the universe can be deduced from the relative abundances of light elements (deuterium, helium and lithium) that were generated during the very first minutes of the cosmic history. This calculation has shown that the baryonic matter represents only 5% of the total mass of the universe. As for neutrinos (hot dark matter), their very low mass restraints their contribution to only 0,3%. The spinning movement of galaxies requires the existence of huge quantity of matter that seems invisible (black matter). Astrophysicists have recently discovered that the universal expansion is accelerating and that the space geometry is euclidean, from these 2 facts they have deduced a value of the mass-energy density that implies the existence of something different from dark matter called dark energy and that is expected to represent about 70% of the mass of the universe. Physicists face the challenge of detecting black matter and black energy. The first attempt for detecting black matter began in 1997 when the UKDMC detector entered into service. Now more than half a dozen of detectors are searching for dark matter but till now in vain. A new generation of detectors (CDMS-2, ZEPLIN-2, CRESST-2 and Edelweiss-2) combining detection, new methods of particle discrimination and the study of the evolution of the signal over very long periods of time are progressively entering into operation. (A.C.)

  16. The Dark Side of Management

    DEFF Research Database (Denmark)

    Hanlon, Gerard; Dunne, Stephen; Johnsen, Christian Garmann

    2017-01-01

    Towards the end of 2015, the ephemera collective organised, chaired and participated within two separate Q+A panels celebrating the launch of Gerard Hanlon’s The dark side of management: A secret history of management theory. The events took place in The University of Leicester’s School...

  17. Black Component of Dark Matter

    Directory of Open Access Journals (Sweden)

    A. V. Grobov

    2014-01-01

    Full Text Available A mechanism of primordial black hole formation with specific mass spectrum is discussed. It is shown that these black holes could contribute to the energy density of dark matter. Our approach is elaborated in the framework of universal extra dimensions.

  18. A dark day for dinosaurs

    Science.gov (United States)

    Edwards, Pete

    2015-11-01

    On average, 91 people are killed by asteroids each year. In her book Dark Matter and the Dinosaurs, theoretical physicist Lisa Randall focuses on a novel question: how did a dinosaur-killing asteroid end up on its collision course with Earth in the first place?

  19. Indirect searches for dark matter

    Indian Academy of Sciences (India)

    ... of almost-standard annihilating dark matter have brought along have been discussed. The main sources of uncertainties that affect this kind of searches are also listed. [Report number: Saclay T11/206, CERN-PH-TH/2011-257, extended version in arXiv:1202.1454], [Prepared for the Proceedings of Lepton–Photon 2011, ...

  20. Modified gravity without dark matter

    NARCIS (Netherlands)

    Sanders, Robert; Papantonopoulos, L

    2007-01-01

    On an empirical level, the most successful alternative to dark matter in bound gravitational systems is the modified Newtonian dynamics, or MOND, proposed by Milgrom. Here I discuss the attempts to formulate MOND as a modification of General Relativity. I begin with a summary of the phenomenological

  1. Weak lensing and dark energy

    International Nuclear Information System (INIS)

    Huterer, Dragan

    2002-01-01

    We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy

  2. Dark matter in NGC 4472

    Science.gov (United States)

    Loewenstein, Michael

    1992-01-01

    An attempt is made to constrain the total mass distribution of the giant elliptical galaxy NGC 4472 by constructing simultaneous equilibrium models for the gas and stars. Emphasis is given to reconciling the value of the emission-weighted average value of kT derived from the Ginga spectrum with the amount of dark matter needed to account for velocity dispersion observations.

  3. Did LIGO Detect Dark Matter?

    Science.gov (United States)

    Bird, Simeon; Cholis, Ilias; Muñoz, Julian B; Ali-Haïmoud, Yacine; Kamionkowski, Marc; Kovetz, Ely D; Raccanelli, Alvise; Riess, Adam G

    2016-05-20

    We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20M_{⊙}≲M_{bh}≲100M_{⊙} where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2-53  Gpc^{-3} yr^{-1} rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next-generation experiments will be invaluable in performing these tests.

  4. Wino dark matter under siege

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy [Theory Group, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025 (United States); Lisanti, Mariangela [Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, 08544 (United States); Pierce, Aaron [Michigan Center for Theoretical Physics, Department of Physics, Ann Arbor, MI, 48109 (United States); Slatyer, Tracy R., E-mail: timcohen@slac.stanford.edu, E-mail: mlisanti@princeton.edu, E-mail: atpierce@umich.edu, E-mail: tslatyer@mit.edu [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ, 08540 (United States)

    2013-10-01

    A fermion triplet of SU(2){sub L} — a wino — is a well-motivated dark matter candidate. This work shows that present-day wino annihilations are constrained by indirect detection experiments, with the strongest limits coming from H.E.S.S. and Fermi. The bounds on wino dark matter are presented as a function of mass for two scenarios: thermal (winos constitute a subdominant component of the dark matter for masses less than 3.1 TeV) and non-thermal (winos comprise all the dark matter). Assuming the NFW halo model, the H.E.S.S. search for gamma-ray lines excludes the 3.1 TeV thermal wino; the combined H.E.S.S. and Fermi results completely exclude the non-thermal scenario. Uncertainties in the exclusions are explored. Indirect detection may provide the only probe for models of anomaly plus gravity mediation where the wino is the lightest superpartner and scalars reside at the 100 TeV scale.

  5. Dark matter in spiral galaxies

    International Nuclear Information System (INIS)

    Albada, T.S. van; Sancisi, R.

    1986-01-01

    Mass models of spiral galaxies based on the observed light distribution, assuming constant M/L for bulge and disc, are able to reproduce the observed rotation curves in the inner regions, but fail to do so increasingly towards and beyond the edge of the visible material. The discrepancy in the outer region can be accounted for by invoking dark matter; some galaxies require at least four times as much dark matter as luminous matter. There is no evidence for a dependence on galaxy luminosity or morphological type. Various arguments support the idea that a distribution of visible matter with constant M/L is responsible for the circular velocity in the inner region, i.e. inside approximately 2.5 disc scalelengths. Luminous matter and dark matter seem to 'conspire' to produce the flat observed rotation curves in the outer region. It seems unlikely that this coupling between disc and halo results from the large-scale gravitational interaction between the two components. Attempts to determine the shape of dark halos have not yet produced convincing results. (author)

  6. 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.

  7. 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.

  8. Dark matter axions and caustic rings

    International Nuclear Information System (INIS)

    Sikivie, P.

    1997-01-01

    This report contains discussions on the following topics: the strong CP problem; dark matter axions; the cavity detector of galactic halo axions; and caustic rings in the density distribution of cold dark matter halos

  9. Analytical theory of dark nonlocal solitons

    DEFF Research Database (Denmark)

    Kong, Qian; Wang, Qi; Bang, Ole

    2010-01-01

    We investigate properties of dark solitons in nonlocal materials with an arbitrary degree of nonlocality. We employ the variational technique and describe dark solitons, for the first time to our knowledge, in the whole range of degree of nonlocality....

  10. Self-interacting warm dark matter

    International Nuclear Information System (INIS)

    Hannestad, Steen; Scherrer, Robert J.

    2000-01-01

    It has been shown by many independent studies that the cold dark matter scenario produces singular galactic dark halos, in strong contrast with observations. Possible remedies are that either the dark matter is warm so that it has significant thermal motion or that the dark matter has strong self-interactions. We combine these ideas to calculate the linear mass power spectrum and the spectrum of cosmic microwave background (CMB) fluctuations for self-interacting warm dark matter. Our results indicate that such models have more power on small scales than is the case for the standard warm dark matter model, with a CMB fluctuation spectrum which is nearly indistinguishable from standard cold dark matter. This enhanced small-scale power may provide better agreement with the observations than does standard warm dark matter. (c) 2000 The American Physical Society

  11. Exploring the dark side of the Universe

    International Nuclear Information System (INIS)

    Das, Mala

    2014-01-01

    Astronomical observations show that about 95% of the energy density of the Universe cannot be accounted for in terms of mass and energy of which about 26.8% is considered to be dark matter. The detection of this dark matter is one of the major and interesting unsolved problems in Physics. There are many experiments running worldwide at different underground laboratories for the direct detection of dark matter, mainly WIMPs (Weakly Interacting Massive Particles), the most favoured candidate of dark matter. Direct detection experiments expect to detect the dark matter directly by measuring the small energy imparted to recoil nuclei in occasional dark matter interactions with detector, stationed at earth's laboratory. In the subsequent sections, the challenges of such experiments are discussed followed by the details on PICASSO/PICO dark matter search experiment at SNO Lab, activities related to this experiment at SINP and the future direction of dark matter experiments

  12. Heart beats from the dark side

    Science.gov (United States)

    Chang, Jin

    2018-01-01

    The Dark Matter Particle Explorer (DAMPE) satellite is currently in orbit measuring cosmic rays to research their origin and propagation and also to find possible hidden signatures of dark matter, emphasizes Principal Investigator Jin Chang.

  13. [Cacoa and dark chocolate in cardiovascular prevention?].

    Science.gov (United States)

    Belz, G G; Mohr-Kahaly, S

    2011-12-01

    It has been shown that the consumption of cocoa has a positive influence on a number of cardiovascular surrogate parameters such as arterial vasodilatation and a moderate decrease in blood pressure in humans. In the blood, a decrease in platelet aggregation and an increase in angiogenetic progenitor cells was noted. Furthermore, anti-inflammatory effects, an amelioration of the lipid profile and glucose metabolism was described. An increase of endothelial NO production following the ingestion of the antioxidant cocoa flavanols catechin and epicatechin seems to be the leading mechanism causing these effects. In animal studies of myocardial reperfusion, a decrease in infarct size was noted. In several prospective cohort studies from Europe and the United States, a 50 % reduction of mortality mostly due to a reduction of myocardial infarction was published. Consumption up to about 25 g daily of a flavanol rich dark chocolate (ca. 85 % cocoa content) can be recommended for cardiovascular prevention. In this moderate dosage, the potentially harmful effects due to weight gain and cadmium intake will be minimal. However, controlled randomized trials with well defined clinical endpoints are needed to prove the positive effects described so far. At this point, in time based on the information described in this article, a moderate consumption of flavanol rich cocoa products seems to be effective in the prevention of coronary artery disease and myocardial infarction. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Dark Sector Mass Relations from RG Focusing

    OpenAIRE

    Kearney, John; Pierce, Aaron

    2013-01-01

    Dark sector mass relations, such as those which permit near-threshold or near-resonance annihilation in the early universe, could arise due to IR-attractive ratios in renormalization group equations. Achieving a particular ratio requires specific dark matter gauge charges or interactions, leading to predictions about the dark matter properties. Furthermore, additional states with masses comparable to the dark matter mass may be necessary, potentially giving rise to novel phenomenology. We exp...

  15. Entropy-Based Dark Frame Subtraction

    OpenAIRE

    Goesele, Michael; Heidrich, Wolfgang; Seidel, Hans-Peter

    2001-01-01

    Noise due to dark current is a serious limitation for taking long exposure time images with a CCD digital camera. Current solutions have serious drawbacks: interpolation of pixels with high dark current leads to smoothing effects or other artifacts -- especially if a large number of pixels are corrupted. Due to the exponential temperature dependence of the dark current, dark frame subtraction works best for temperature controlled high end CCD imaging systems. On the ...

  16. Fuzzy dark matter and nonstandard neutrino interactions

    OpenAIRE

    Brdar, Vedran; Kopp, Joachim; Liu, Jia; Prass, Pascal; Wang, Xiao-Ping

    2018-01-01

    We discuss novel ways in which neutrino oscillation experiments can probe dark matter. In particular, we focus on interactions between neutrinos and ultralight (“fuzzy”) dark matter particles with masses of order 10−22 eV. It has been shown previously that such dark matter candidates are phenomenologically successful and might help ameliorate the tension between predicted and observed small scale structures in the Universe. We argue that coherent forward scattering of neutrinos on fuzzy dark...

  17. Quantum mechanical theory behind "dark energy"?

    CERN Multimedia

    Colin Johnson, R

    2007-01-01

    "The mysterious increase in the acceleration of the universe, when intuition says it should be slowing down, is postulated to be caused by dark energy - "dark" because it is undetected. Now a group of scientists in the international collaboration Essence has suggested that a quantum mechanical interpretation of Einstein's proposed "cosmological constant" is the simplest explanation for dark energy. The group measured dark energy to within 10 percent." (1,5 page)

  18. New Spectral Features from Bound Dark Matter

    DEFF Research Database (Denmark)

    Catena, Riccardo; Kouvaris, Chris

    2016-01-01

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments...... with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section....

  19. 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...

  20. Big Bang synthesis of nuclear dark matter

    International Nuclear Information System (INIS)

    Hardy, Edward; Lasenby, Robert; March-Russell, John; West, Stephen M.

    2015-01-01

    We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark “nucleon” number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. ≳10 8 , may be synthesised, with the number distribution taking one of two characteristic forms. If small-nucleon-number fusions are sufficiently fast, the distribution of dark nuclei takes on a logarithmically-peaked, universal form, independent of many details of the initial conditions and small-number interactions. In the case of a substantial bottleneck to nucleosynthesis for small dark nuclei, we find the surprising result that even larger nuclei, with size ≫10 8 , are often finally synthesised, again with a simple number distribution. We briefly discuss the constraints arising from the novel dark sector energetics, and the extended set of (often parametrically light) dark sector states that can occur in complete models of nuclear dark matter. The physics of the coherent enhancement of direct detection signals, the nature of the accompanying dark-sector form factors, and the possible modifications to astrophysical processes are discussed in detail in a companion paper.

  1. Dark Sectors 2016 Workshop: Community Report

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Jim; et al.

    2016-08-30

    This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years.

  2. Agegraphic dark energy as a quintessence

    International Nuclear Information System (INIS)

    Zhang, Jingfei; Liu, Hongya; Zhang, Xin

    2008-01-01

    Recently, a dark energy model characterized by the age of the universe, dubbed ''agegraphic dark energy'', was proposed by Cai. In this paper, a connection between the quintessence scalar-field and the agegraphic dark energy is established, and accordingly, the potential of the agegraphic quintessence field is constructed. (orig.)

  3. 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.

  4. Dark energy interacting with two fluids

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile)], E-mail: ncruz@lauca.usach.cl; Lepe, Samuel [Instituto de Fisica, Facultad de Ciencias Basicas y Matematicas, Universidad Catolica de Valparaiso, Avenida Brasil 2950, Valparaiso (Chile)], E-mail: slepe@ucv.cl; 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)], E-mail: fcampos@ufro.cl

    2008-05-29

    A cosmological model of dark energy interacting with dark matter and another general component of the universe is investigated. We found general constraints on these models imposing an accelerated expansion. The same is also studied in the case for holographic dark energy.

  5. Formation of multiple dark photovoltaic spatial solitons

    Indian Academy of Sciences (India)

    We theoretically study the formation of multiple dark photovoltaic soliton splitting in the quasi-steady-state and steady-state regimes under open-circuit conditions. We find that the initial width of the dark notch at the entrance face of the crystal is a key parameter for generating an even (or odd) number sequence of dark ...

  6. Dark Sectors 2016 Workshop: Community Report

    CERN Document Server

    Alexander, Jim; Echenard, Bertrand; Essig, Rouven; Graham, Matthew; Izaguirre, Eder; Jaros, John; Krnjaic, Gordan; Mardon, Jeremy; Morrissey, David; Nelson, Tim; Perelstein, Maxim; Pyle, Matt; Ritz, Adam; Schuster, Philip; Shuve, Brian; Toro, Natalia; Van De Water, Richard G.; Akerib, Daniel; An, Haipeng; Aniol, Konrad; Arnquist, Isaac J.; Asner, David M.; Back, Henning O.; Baker, Keith; Baltzell, Nathan; Banerjee, Dipanwita; Batell, Brian; Bauer, Daniel; Beacham, James; Benesch, Jay; Bjorken, James; Blinov, Nikita; Boehm, Celine; Bondi, Mariangela; Bonivento, Walter; Bossi, Fabio; Brodsky, Stanley J.; Budnik, Ran; Bueltmann, Stephen; Bukhari, Masroor H.; Bunker, Raymond; Carpinelli, Massimo; Cartaro, Concetta; Cassel, David; Cavoto, Gianluca; Celentano, Andrea; Chaterjee, Animesh; Chaudhuri, Saptarshi; Chiodini, Gabriele; Cho, Hsiao-Mei Sherry; Church, Eric D.; Cooke, D.A.; Cooley, Jodi; Cooper, Robert; Corliss, Ross; Crivelli, Paolo; Curciarello, Francesca; D'Angelo, Annalisa; Davoudiasl, Hooman; De Napoli, Marzio; De Vita, Raffaella; Denig, Achim; deNiverville, Patrick; Deshpande, Abhay; Dharmapalan, Ranjan; Dobrescu, Bogdan; Donskov, Sergey; Dupre, Raphael; Estrada, Juan; Fegan, Stuart; Ferber, Torben; Field, Clive; Figueroa-Feliciano, Enectali; Filippi, Alessandra; Fornal, Bartosz; Freyberger, Arne; Friedland, Alexander; Galon, Iftach; Gardner, Susan; Girod, Francois-Xavier; Gninenko, Sergei; Golutvin, Andrey; Gori, Stefania; Grab, Christoph; Graziani, Enrico; Griffioen, Keith; Haas, Andrew; Harigaya, Keisuke; Hearty, Christopher; Hertel, Scott; Hewett, JoAnne; Hime, Andrew; Hitlin, David; Hochberg, Yonit; Holt, Roy J.; Holtrop, Maurik; Hoppe, Eric W.; Hossbach, Todd W.; Hsu, Lauren; Ilten, Phil; Incandela, Joe; Inguglia, Gianluca; Irwin, Kent; Jaegle, Igal; Johnson, Robert P.; Kahn, Yonatan; Kalicy, Grzegorz; Kang, Zhong-Bo; Khachatryan, Vardan; Kozhuharov, Venelin; Krasnikov, N.V.; Kubarovsky, Valery; Kuflik, Eric; Kurinsky, Noah; Laha, Ranjan; Lanfranchi, Gaia; Li, Dale; Lin, Tongyan; Lisanti, Mariangela; Liu, Kun; Liu, Ming; Loer, Ben; Loomba, Dinesh; Lyubovitskij, Valery E.; Manalaysay, Aaron; Mandaglio, Giuseppe; Mans, Jeremiah; Marciano, W.J.; Markiewicz, Thomas; Marsicano, Luca; Maruyama, Takashi; Matveev, Victor A.; McKeen, David; McKinnon, Bryan; McKinsey, Dan; Merkel, Harald; Mock, Jeremy; Monzani, Maria Elena; Moreno, Omar; Nantais, Corina; Paul, Sebouh; Peskin, Michael; Poliakov, Vladimir; Polosa, Antonio D.; Pospelov, Maxim; Rachek, Igor; Radics, Balint; Raggi, Mauro; Randazzo, Nunzio; Ratcliff, Blair; Rizzo, Alessandro; Rizzo, Thomas; Robinson, Alan; Rubbia, Andre; Rubin, David; Rueter, Dylan; Saab, Tarek; Santopinto, Elena; Schnee, Richard; Shelton, Jessie; Simi, Gabriele; Simonyan, Ani; Sipala, Valeria; Slone, Oren; Smith, Elton; Snowden-Ifft, Daniel; Solt, Matthew; Sorensen, Peter; Soreq, Yotam; Spagnolo, Stefania; Spencer, James; Stepanyan, Stepan; Strube, Jan; Sullivan, Michael; Tadepalli, Arun S.; Tait, Tim; Taiuti, Mauro; Tanedo, Philip; Tayloe, Rex; Thaler, Jesse; Tran, Nhan V.; Tulin, Sean; Tully, Christopher G.; Uemura, Sho; Ungaro, Maurizio; Valente, Paolo; Vance, Holly; Vavra, Jerry; Volansky, Tomer; von Krosigk, Belina; Whitbeck, Andrew; Williams, Mike; Wittich, Peter; Wojtsekhowski, Bogdan; Xue, Wei; Yoon, Jong Min; Yu, Hai-Bo; Yu, Jaehoon; Yu, Tien-Tien; Zhang, Yue; Zhao, Yue; Zhong, Yiming; Zurek, Kathryn

    2016-01-01

    This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years.

  7. Dark matter searches at the LHC

    CERN Document Server

    Hong, Tae Min; The ATLAS collaboration

    2017-01-01

    We present a summary of the current status of searches for dark matter at the LHC from the ATLAS and CMS experiments. For various assumptions in the simplified parameter space, the LHC exclusions is complementary to direct detection results. Mono-object analyses in search of dark matter and various analyses searching for dark matter mediators are presented.

  8. Gravity resonance spectroscopy constrains dark energy and dark matter scenarios.

    Science.gov (United States)

    Jenke, T; Cronenberg, G; Burgdörfer, J; Chizhova, L A; Geltenbort, P; Ivanov, A N; Lauer, T; Lins, T; Rotter, S; Saul, H; Schmidt, U; Abele, H

    2014-04-18

    We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14  eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant β>5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ=20  μm (95% C.L.).

  9. 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

  10. Supernovae and Weinberg's Higgs portal dark radiation and dark matter

    Science.gov (United States)

    Tu, Huitzu; Ng, Kin-Wang

    2017-07-01

    The observed burst duration and energies of the neutrinos from Supernova 1987A strongly limit the possibility of any weakly-interacting light particle species being produced in the proto-neutron star (PNS) core and leading to efficient energy loss. We reexamine this constraint on Weinberg's Higgs portal model, in which the dark radiation particles (the Goldstone bosons) and the dark matter candidate (a Majorana fermion) interact with Standard Model (SM) fields solely through the mixing of the SM Higgs boson and a light Higgs boson. In order for the Goldstone bosons to freely stream out of the PNS core region, the Higgs portal coupling has to be about a factor of 4-9 smaller than the current collider bound inferred from the SM Higgs invisible decay width. We find that in the energy loss rate calculations, results obtained by using the one-pion exchange (OPE) approximation and the SP07 global fits for the nucleon-nucleon total elastic cross section differ only by a factor ≲ 3. The SN 1987A constraints surpass those set by laboratory experiments or by the energy loss arguments in other astrophysical objects such as the gamma-ray bursts, even with other nuclear uncertainties taken into account. Furthermore, the SN 1987A constraints are comparable to bounds from the latest dark matter direct search for low-mass WIMPs (≲10 GeV.)

  11. 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.

  12. 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

  13. Dark Matter Annihilation at the Galactic Center

    Energy Technology Data Exchange (ETDEWEB)

    Linden, Timothy Ryan [Univ. of California, Santa Cruz, CA (United States)

    2013-06-01

    Observations by the WMAP and PLANCK satellites have provided extraordinarily accurate observations on the densities of baryonic matter, dark matter, and dark energy in the universe. These observations indicate that our universe is composed of approximately ve times as much dark matter as baryonic matter. However, e orts to detect a particle responsible for the energy density of dark matter have been unsuccessful. Theoretical models have indicated that a leading candidate for the dark matter is the lightest supersymmetric particle, which may be stable due to a conserved R-parity. This dark matter particle would still be capable of interacting with baryons via weak-force interactions in the early universe, a process which was found to naturally explain the observed relic abundance of dark matter today. These residual annihilations can persist, albeit at a much lower rate, in the present universe, providing a detectable signal from dark matter annihilation events which occur throughout the universe. Simulations calculating the distribution of dark matter in our galaxy almost universally predict the galactic center of the Milky Way Galaxy (GC) to provide the brightest signal from dark matter annihilation due to its relative proximity and large simulated dark matter density. Recent advances in telescope technology have allowed for the rst multiwavelength analysis of the GC, with suitable e ective exposure, angular resolution, and energy resolution in order to detect dark matter particles with properties similar to those predicted by the WIMP miracle. In this work, I describe ongoing e orts which have successfully detected an excess in -ray emission from the region immediately surrounding the GC, which is di cult to describe in terms of standard di use emission predicted in the GC region. While the jury is still out on any dark matter interpretation of this excess, I describe several related observations which may indicate a dark matter origin. Finally, I discuss the

  14. 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...

  15. The DarkSide Program at LNGS

    OpenAIRE

    Wright, Alex; Collaboration, for the DarkSide

    2011-01-01

    DarkSide is a direct detection dark matter program based on two phase time projection chambers with depleted argon targets. The DarkSide detectors are designed, using novel low background techniques and active shielding, to be capable of demonstrating in situ a very low level of residual background. This means that each detector in the DarkSide program should have the ability to make a convincing claim of dark matter detection based on the observation of a few nuclear recoil events. The colla...

  16. Laser Probes of the Dark Sector

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Dark matter, dark energy, and gravity are fundamental components of the standard cosmological model, and their macroscopic effects on the evolution of the universe are well documented. However, the quantum properties of these fields remain largely unknown. An ongoing suite of laser experiments at Fermilab have conducted searches for axion-like dark matter, tested particle models of dark energy, and plans to test certain predictions of black hole thermodynamics---namely the holographic principle. I will present the results from the GammeV search for milli-eV axion-like particles and will discuss in detail the recently completed CHASE search for chameleon dark energy.

  17. 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.

  18. Superconducting Detectors for Superlight Dark Matter.

    Science.gov (United States)

    Hochberg, Yonit; Zhao, Yue; Zurek, Kathryn M

    2016-01-08

    We propose and study a new class of superconducting detectors that are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, m(X)≳1  keV. We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.

  19. Dark matter from split seesaw

    International Nuclear Information System (INIS)

    Kusenko, Alexander; Takahashi, Fuminobu; Yanagida, Tsutomu T.

    2010-01-01

    The seesaw mechanism in models with extra dimensions is shown to be generically consistent with a broad range of Majorana masses. The resulting democracy of scales implies that the seesaw mechanism can naturally explain the smallness of neutrino masses for an arbitrarily small right-handed neutrino mass. If the scales of the seesaw parameters are split, with two right-handed neutrinos at a high scale and one at a keV scale, one can explain the matter-antimatter asymmetry of the universe, as well as dark matter. The dark matter candidate, a sterile right-handed neutrino with mass of several keV, can account for the observed pulsar velocities and for the recent data from Chandra X-ray Observatory, which suggest the existence of a 5 keV sterile right-handed neutrino.

  20. Light and Dark Slope Streaks

    Science.gov (United States)

    2004-01-01

    21 July 2004 Dark slope streaks are a common feature on slopes thickly-mantled by dust, especially in the Tharsis, Arabia, and western Amazonis regions of Mars. Less common are light-toned slope streaks, which often occur in the same area as dark streaks. They are most common in Arabia Terra, and some are shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Slope streaks are probably the result of sudden avalanches of extremely dry dust. The behavior of the avalanching dust is somewhat fluid-like, and new streaks have been observed to form over intervals of a few months to a Mars year. This image is located near 13.4oN, 340.3oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  1. A viable dark fluid model

    Science.gov (United States)

    Elkhateeb, Esraa

    2018-01-01

    We consider a cosmological model based on a generalization of the equation of state proposed by Nojiri and Odintsov (2004) and Štefančić (2005, 2006). We argue that this model works as a dark fluid model which can interpolate between dust equation of state and the dark energy equation of state. We show how the asymptotic behavior of the equation of state constrained the parameters of the model. The causality condition for the model is also studied to constrain the parameters and the fixed points are tested to determine different solution classes. Observations of Hubble diagram of SNe Ia supernovae are used to further constrain the model. We present an exact solution of the model and calculate the luminosity distance and the energy density evolution. We also calculate the deceleration parameter to test the state of the universe expansion.

  2. Dark Matter in the Universe

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The question “What is the Universe made of?” is the longest outstanding problem in all of physics. Ordinary atoms only constitute 5% of the total, while the rest is of unknown composition. Already in 1933 Fritz Zwicky observed that the rapid motions of objects within clusters of galaxies were unexplained by the gravitation pull of luminous matter, and he postulated the existence of Dunkle Materie, or dark matter. A variety of dark matter candidates exist, including new fundamental particles already postulated in particle theories: axions and WIMPs (weakly interacting massive particles). Over the past 25 years, there has been a three pronged approach to WIMP detection: creating them at particle accelerators; searched for detection of astrophysical WIMPs scattering off of nuclei in underground detectors; and “indirect detection” of WIMP annihilation products (neutrinos, positrons, or photons). As yet the LHC has only placed bounds rather than finding discovery. For 13 years the DAMA experiment has proc...

  3. Dark matter versus Mach's principle.

    Science.gov (United States)

    von Borzeszkowski, H.-H.; Treder, H.-J.

    1998-02-01

    Empirical and theoretical evidence show that the astrophysical problem of dark matter might be solved by a theory of Einstein-Mayer type. In this theory up to global Lorentz rotations the reference system is determined by the motion of cosmic matter. Thus one is led to a "Riemannian space with teleparallelism" realizing a geometric version of the Mach-Einstein doctrine. The field equations of this gravitational theory contain hidden matter terms where the existence of hidden matter is inferred safely from its gravitational effects. It is argued that in the nonrelativistic mechanical approximation they provide an inertia-free mechanics where the inertial mass of a body is induced by the gravitational action of the comic masses. Interpreted form the Newtonian point of view this mechanics shows that the effective gravitational mass of astrophysical objects depends on r such that one expects the existence of dark matter.

  4. Oscillating spin-2 dark matter

    Science.gov (United States)

    Marzola, Luca; Raidal, Martti; Urban, Federico R.

    2018-01-01

    The negative outcomes of laboratory searches, juxtaposed with cosmological observations, may indicate that dark matter has a gravitational origin. We show that coherent oscillations of a massive spin-2 field emerging from bimetric theory can easily account for the observed dark matter abundance. The framework, based on the only known consistent extension of general relativity to interacting spin-2 fields, is testable in precision measurements of the electric charge variation by means of atomic clocks, molecular systems, dedicated resonant mass detectors, as well as gravity interferometers and axionlike-particle experiments. These searches, therefore, provide a new window into the phenomenology of gravity which complements the results of dedicated tests of gravitation. We also present a multimetric extension of the scenario that straightforwardly implements the clockwork mechanism for gravity, explaining the apparent weakness of this force.

  5. Josephson junctions and dark energy

    Science.gov (United States)

    Jetzer, Philippe; Straumann, Norbert

    2006-08-01

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy has nothing to do with the proposed measurements.

  6. Josephson junctions and dark energy

    International Nuclear Information System (INIS)

    Jetzer, Philippe; Straumann, Norbert

    2006-01-01

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy has nothing to do with the proposed measurements

  7. Josephson junctions and dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Jetzer, Philippe [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)]. E-mail: jetzer@physik.unizh.ch; Straumann, Norbert [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

    2006-08-03

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy hathing to do with the proposed measurements.

  8. 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.

  9. 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

  10. Electrodynamics of a Cosmic Dark Fluid

    Directory of Open Access Journals (Sweden)

    Alexander B. Balakin

    2016-06-01

    Full Text Available Cosmic Dark Fluid is considered as a non-stationary medium, in which electromagnetic waves propagate, and magneto-electric field structures emerge and evolve. A medium-type representation of the Dark Fluid allows us to involve in its analysis the concepts and mathematical formalism elaborated in the framework of classical covariant electrodynamics of continua, and to distinguish dark analogs of well-known medium-effects, such as optical activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a Dark Matter (a pseudoscalar axionic constituent and Dark Energy (a scalar element; respectively, we distinguish electrodynamic effects induced by these two constituents of the Dark Fluid. The review contains discussions of 10 models, which describe electrodynamic effects induced by Dark Matter and/or Dark Energy. The models are accompanied by examples of exact solutions to the master equations, correspondingly extended; applications are considered for cosmology and space-times with spherical and pp-wave symmetries. In these applications we focused the attention on three main electromagnetic phenomena induced by the Dark Fluid: first, emergence of Longitudinal Magneto-Electric Clusters; second, generation of anomalous electromagnetic responses; third, formation of Dark Epochs in the Universe history.

  11. Flavored dark matter beyond Minimal Flavor Violation

    International Nuclear Information System (INIS)

    Agrawal, Prateek; Blanke, Monika; Gemmler, Katrin

    2014-01-01

    We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a U(3) χ associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter χ which transforms as triplet under U(3) χ , and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator with a coupling. We identify a number of ''flavor-safe'' scenarios for the structure of which are beyond Minimal Flavor Violation. Also, for dark matter and collider phenomenology we focus on the well-motivated case of b-flavored dark matter. Furthermore, the combined flavor and dark matter constraints on the parameter space of turn out to be interesting intersections of the individual ones. LHC constraints on simplified models of squarks and sbottoms can be adapted to our case, and monojet searches can be relevant if the spectrum is compressed

  12. Blood culture

    Science.gov (United States)

    Culture - blood ... A blood sample is needed . The site where blood will be drawn is first cleaned with an antiseptic such ... organism from the skin getting into (contaminating) the blood sample and causing a false-positive result (see ...

  13. A galaxy lacking dark matter

    Science.gov (United States)

    van Dokkum, Pieter; Danieli, Shany; Cohen, Yotam; Merritt, Allison; Romanowsky, Aaron J.; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Lokhorst, Deborah; Mowla, Lamiya; O'Sullivan, Ewan; Zhang, Jielai

    2018-03-01

    Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 1010 solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052–DF2, which has a stellar mass of approximately 2 × 108 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 108 solar masses. This implies that the ratio Mhalo/Mstars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052–DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

  14. A galaxy lacking dark matter.

    Science.gov (United States)

    van Dokkum, Pieter; Danieli, Shany; Cohen, Yotam; Merritt, Allison; Romanowsky, Aaron J; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Lokhorst, Deborah; Mowla, Lamiya; O'Sullivan, Ewan; Zhang, Jielai

    2018-03-28

    Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio M halo /M stars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 10 10 solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052-DF2, which has a stellar mass of approximately 2 × 10 8 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 10 8 solar masses. This implies that the ratio M halo /M stars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052-DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

  15. 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.

  16. DDO 154 - A dark galaxy?

    International Nuclear Information System (INIS)

    Carignan, C.; Freeman, K.C.

    1988-01-01

    The mass distribution of the gas-rich dwarf irregular galaxy DDO 154 is studied. The large extent of the H I component allows us to determine unambiguously the rotation curve out to 4R(HO) (7R sub 25, 15/alpha). In terms of optical scale lengths, this is one of the longest rotation curves ever measured. At those large galactocentric distances, the flat part of the rotation curve is reached which permits much better constraints on the parameters of the mass model and especially of the dark halo component. The best-fitting model yields a core radius of 3.0 kpc and a central density of 0.016 solar masses/cu pc for the isothermal halo. For the stellar disk, it is found that M/L(B) = 1.0. For r greater than 1 kpc, the rotation curve is completely dominated by the dark component. At the last point of the rotation curve (7.6 kpc), more than 90 percent of the mass is provided by the dark component. At that radius, M/L(B)(total) = 80. The results for DDO 154 show that there exist galaxies where the luminous matter (stars and gas) is only a minor component of the total galaxy mass. This also suggests that it is possible that many of the smallest galaxies could be optically invisible. 23 references

  17. 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.

  18. Common origin of visible and dark universe

    International Nuclear Information System (INIS)

    Gu Peihong; Sarkar, Utpal

    2010-01-01

    Dark matter, baryonic matter, and dark energy have different properties but contribute comparable energy density to the present Universe. We point out that they may have a common origin. As the dark energy has a scale far lower than all known scales in particle physics but very close to neutrino masses, while the excess matter over antimatter in the baryonic sector is probably related to the neutrino-mass generation, we unify the origin of the dark and visible universe in a variant of the seesaw model. In our model (i) the dark matter relic density is a dark matter asymmetry emerged simultaneously with the baryon asymmetry from leptogenesis; (ii) the dark energy is due to a pseudo-Nambu-Goldstone-Boson associated with the neutrino-mass generation.

  19. Baryon destruction by asymmetric dark matter

    International Nuclear Information System (INIS)

    Davoudiasl, Hooman; Morrissey, David E.; Tulin, Sean; Sigurdson, Kris

    2011-01-01

    We investigate new and unusual signals that arise in theories where dark matter is asymmetric and carries a net antibaryon number, as may occur when the dark matter abundance is linked to the baryon abundance. Antibaryonic dark matter can cause induced nucleon decay by annihilating visible baryons through inelastic scattering. These processes lead to an effective nucleon lifetime of 10 29 -10 32 yrs in terrestrial nucleon decay experiments, if baryon number transfer between visible and dark sectors arises through new physics at the weak scale. The possibility of induced nucleon decay motivates a novel approach for direct detection of cosmic dark matter in nucleon decay experiments. Monojet searches (and related signatures) at hadron colliders also provide a complementary probe of weak-scale dark-matter-induced baryon number violation. Finally, we discuss the effects of baryon-destroying dark matter on stellar systems and show that it can be consistent with existing observations.

  20. The Cosmology of Composite Inelastic Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Spier Moreira Alves, Daniele; Behbahani, Siavosh R.; /SLAC /Stanford U., ITP; Schuster, Philip; Wacker, Jay G.; /SLAC

    2011-08-19

    Composite dark matter is a natural setting for implementing inelastic dark matter - the O(100 keV) mass splitting arises from spin-spin interactions of constituent fermions. In models where the constituents are charged under an axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark matter scatters inelastically off Standard Model nuclei and can explain the DAMA/LIBRA annual modulation signal. This article describes the early Universe cosmology of a minimal implementation of a composite inelastic dark matter model where the dark matter is a meson composed of a light and a heavy quark. The synthesis of the constituent quarks into dark hadrons results in several qualitatively different configurations of the resulting dark matter composition depending on the relative mass scales in the system.

  1. Dark triad traits and health outcomes: An exploratory study

    Directory of Open Access Journals (Sweden)

    Jasna Hudek-Knežević

    2016-04-01

    Full Text Available On the sample of 637 participants (358 women and 279 men we explored the relationshipbetween Dark Triad traits (psychopathy, Machiavellianism and Narcissism and various healthindicators including subjective (positive and negative mood and perceived physical symptoms,protective health behaviors as well as some more objective health indicators (number ofhospitalizations, number of diseases, having specific chronic diseases, injuries and addictions.Because of the moderate relations between Dark Triad and broad personality traits that also exerttheir influence on various health-related indices, we examined the unique effects of Dark Triad traitson health indicators above and beyond five-factor personality traits as well as sociodemographicvariables related to health (gender, age and education.When sociodemographic variables, as well as five-factor personality traits were controlled inhierarchical regression analyses, Dark Triad traits significantly improved the prediction of almostall subjective health indicators, protective health behaviors, number of hospitalizations and numberof diseases. The effect sizes obtained were relatively low, and psychopathy was the most consistentpredictor.Regarding chronic diseases, injuries and addictions, the results of hierarchical binary logisticregressions showed that when sociodemographic variables were controlled, psychopathy was apositive predictor of the risk of digestive diseases, tobacco use and injuries, Machiavellianismnegatively predicted the risk of injuries, while Narcissism negatively predicted the risk of skindiseases and tobacco use. When five-factor personality traits were controlled, psychopathy was alsoa positive predictor of digestive diseases, tobacco use and injuries. Machiavellianism was a positivepredictor of high blood pressure, and negative predictor of cancer, spine and back diseases andinjuries, while Narcissism was a negative predictor of skin diseases.The results obtained are discussed

  2. Dark chocolate and reduced snack consumption in mildly hypertensive adults: an intervention study.

    Science.gov (United States)

    Koli, Raika; Köhler, Klaus; Tonteri, Elina; Peltonen, Juha; Tikkanen, Heikki; Fogelholm, Mikael

    2015-08-22

    Several studies have shown that cocoa and cocoa-containing foods have the potential to lower blood pressure and improve endothelial function. Most of the studies reporting the beneficial effects of dark chocolate on blood pressure have been short (≤ 4 weeks). The aim of the present 8-wks (weeks) study was to assess the effects of regular consumption of dark chocolate during a reduced snack consumption intervention on blood pressure and other cardiovascular risk factors in mildly hypertensive individuals. This was a randomized, controlled, cross-over trial involving 22 adults (8 women, 14 men), aged 33-64 y, BMI 27.7 ± 3.7 kg/m(2) with mild hypertension. During the intervention period (8-wks) the participants reduced the intake of habitual snacks and replaced them with dark chocolate (49 g/day). In the control period, they only reduced the snacks without any added chocolate. Data (blood lipid profile, glucose, insulin, 24 h blood pressure) was collected in the beginning and end of both periods (intervention and control), and some variables also in the run-in and run-out periods (weight, body fat percentage, blood pressure, arterial stiffness index, diet and physical activity). Daily consumption of dark chocolate had no effects on 24 h blood pressure, resting blood pressure (mean ± SD, pre 142 ± 11.5/89 ± 8.4 mmHg vs. post 142 ± 14.2/88 ± 9.4 mmHg in systolic and diastolic blood pressure, respectively) or arterial stiffness (mean ± SD, pre 7.68 ± 0.88 vs. post 7.76 ± 0.89). Weight was reduced by 1.0 ± 2.2 kg during the control (reduced snack only) period, but was unchanged while eating chocolate (p snack period. ClinicalTrials.gov identifier NCT02130141.

  3. Dark refraction shift with allowance for astigmatism

    Directory of Open Access Journals (Sweden)

    W.D.H. Gillan

    2005-12-01

    Full Text Available Purpose: To show that the dark refraction shift (dark focus is a more complicated phenomenon than implied when presented as spherical. Methods: Fifty autorefractor measurements of refractive state of the right eye were obtained in light  and  dark  conditions.  Multivariate  methods were used to analyze the data and stereo-pair scat-ter plots, polar meridional profiles and other means of presenting results are used to show important characteristics of the dark refraction shift. Results: The complexity of the dark refrac-tion shift is indicated by stereo-pair scatter plots showing the amount of stigmatic and antistigmatic variation that occurs in light and dark conditions. The mean dark refraction shift is presented in a complete manner including all three components of refractive state. The greater variance and covari-ance under dark conditions is clearly shown by the term-by-term dark-light variance-covariance ratio and polar profiles  of variance and covariance.Conclusions: The  dark  refraction  shift  is  a more complicated phenomenon than implied by representations as purely spherical in nature.

  4. Mirror dark matter and large scale structure

    International Nuclear Information System (INIS)

    Ignatiev, A.Yu.; Volkas, R.R.

    2003-01-01

    Mirror matter is a dark matter candidate. In this paper, we reexamine the linear regime of density perturbation growth in a universe containing mirror dark matter. Taking adiabatic scale-invariant perturbations as the input, we confirm that the resulting processed power spectrum is richer than for the more familiar cases of cold, warm and hot dark matter. The new features include a maximum at a certain scale λ max , collisional damping below a smaller characteristic scale λ S ' , with oscillatory perturbations between the two. These scales are functions of the fundamental parameters of the theory. In particular, they decrease for decreasing x, the ratio of the mirror plasma temperature to that of the ordinary. For x∼0.2, the scale λ max becomes galactic. Mirror dark matter therefore leads to bottom-up large scale structure formation, similar to conventional cold dark matter, for x(less-or-similar sign)0.2. Indeed, the smaller the value of x, the closer mirror dark matter resembles standard cold dark matter during the linear regime. The differences pertain to scales smaller than λ S ' in the linear regime, and generally in the nonlinear regime because mirror dark matter is chemically complex and to some extent dissipative. Lyman-α forest data and the early reionization epoch established by WMAP may hold the key to distinguishing mirror dark matter from WIMP-style cold dark matter

  5. Dark matter at the Fermi scale

    International Nuclear Information System (INIS)

    Feng, Jonathan L

    2006-01-01

    Recent breakthroughs in cosmology reveal that a quarter of the Universe is composed of dark matter, but the microscopic identity of dark matter remains a deep mystery. I review recent progress in resolving this puzzle, focusing on two well-motivated classes of dark matter candidates: weakly interacting massive particles (WIMPs) and superWIMPs. These possibilities have similar motivations: they exist in the same well-motivated particle physics models, the observed dark matter relic density emerges naturally and dark matter particles have mass around 100 GeV, the energy scale identified as interesting over 70 years ago by Fermi. At the same time, they have widely varying implications for direct and indirect dark matter searches, particle colliders, Big Bang nucleosynthesis, the cosmic microwave background, and halo profiles and structure formation. If WIMPs or superWIMPs are a significant component of dark matter, we will soon be entering a golden era in which dark matter will be studied through diverse probes at the interface of particle physics, astroparticle physics and cosmology. I outline a programme of dark matter studies for each of these scenarios and discuss the prospects for identifying dark matter in the coming years. (topical review)

  6. Weakly interacting dark matter and baryogenesis

    International Nuclear Information System (INIS)

    Gu Peihong; Lindner, Manfred; Sarkar, Utpal; Zhang Xinmin

    2011-01-01

    In the present Universe visible and dark matter contribute comparable energy density although they have different properties. This phenomenon can be explained if the dark matter relic density, originating from a dark matter asymmetry, is fully determined by the baryon asymmetry. Thus the dark matter mass is not arbitrary; rather, it becomes predictive. We realize this scenario in baryon (lepton) number conserving models where two or more neutral singlet scalars decay into two or three baryonic (leptonic) dark matter scalars, and also decay into quarks (leptons) through other on-shell and/or off-shell exotic scalar bilinears. The produced baryon (lepton) asymmetries in the dark matter scalar and in the standard model quarks (leptons) are thus equal and opposite. The dark matter mass can be predicted in a range from a few GeV to a few TeV, depending on the baryon (lepton) numbers of the decaying scalars and the dark matter scalar. The dark matter scalar can interact with the visible matter through the exchange of the standard model Higgs boson, opening a window for the dark matter direct detection experiments. These models also provide testable predictions in the searches for the exotic scalar bilinears at LHC.

  7. 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.

  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. 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. Dark goo: Bulk viscosity as an alternative to dark energy

    CERN Document Server

    Gagnon, Jean-Sebastien

    2011-01-01

    We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective" pressure containing the bulk viscosity. For a sufficiently large bulk viscosity, the effective pressure becomes negative and could mimic a dark energy equation of state. Our microscopic model includes self-interacting spin-zero particles (for which the bulk viscosity is known) that are added to the usual energy content of the universe. We study both background equations and linear perturbations in this model. We show that a dark energy behavior is obtained for reasonable values of the two parameters of the model (i.e. the mass and coupling of the spin-zero particles) and that linear perturbations are well-behaved. There is no apparent fine tuning involved. We also discuss the conditions under which hydrodynamics holds, in particular that the spin-zero particles must be in local eq...

  11. Dark matter in the universe

    Science.gov (United States)

    Turner, Michael S.

    1991-01-01

    What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand. Most of the radiation in the Universe does not give off detectable radiation; it is dark. The dark matter associated with bright galaxies contributes somewhere between 10 and 30 percent of the critical density; baryonic matter contributes between 1.1 and 12 percent of the critical. The case for the spatially flat, Einstein-de Sitter model is supported by three compelling theoretical arguments - structure formation, the temporal Copernican principle, and inflation - and by some observational data. If Omega is indeed unity, or even just significantly greater than 0.1, then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark matter candidates: an axion of mass 10 (exp -6) eV to 10 (exp -4) eV; a neutrino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either planned or are underway.

  12. Dark matter in the universe

    International Nuclear Information System (INIS)

    Turner, M.S.; Chicago Univ., IL

    1990-11-01

    What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: Most of the material in the Universe does not give off detectable radiation, i.e., is ''dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments--structure formation, the temporal Copernican principle, and inflation--and by some observational data. If Ω is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10 -6 eV to 10 -4 eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 63 refs

  13. Dark matter in the universe

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-11-01

    What is the quantity and composition of material in the Universe This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: Most of the material in the Universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments--structure formation, the temporal Copernican principle, and inflation--and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 63 refs.

  14. Dark matter in the Universe

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-03-01

    What is the quantity and composition of material in the universe This is one of the most fundamental questions we can ask about the universe, and its answer bears on a number of important issues including the formation of structure in the universe, and the ultimate fate and the earliest history of the universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: most of the material in the universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments -- structure formation, the temporal Copernican principle, and inflation -- and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 71 refs., 6 figs.

  15. Dark Matter in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Cotta, R.C.; Gainer, J.S.; Hewett, J.L.; Rizzo, T.G.; /SLAC

    2009-04-07

    We have recently examined a large number of points in the parameter space of the phenomenological MSSM, the 19-dimensional parameter space of the CP-conserving MSSM with Minimal Flavor Violation. We determined whether each of these points satisfied existing experimental and theoretical constraints. This analysis provides insight into general features of the MSSM without reference to a particular SUSY breaking scenario or any other assumptions at the GUT scale. This study opens up new possibilities for SUSY phenomenology both in colliders and in astrophysical experiments. Here we shall discuss the implications of this analysis relevant to the study of dark matter.

  16. Strongly Interacting Light Dark Matter

    Directory of Open Access Journals (Sweden)

    Sebastian Bruggisser, Francesco Riva, Alfredo Urbano

    2017-09-01

    Full Text Available In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM can appear weakly coupled at small energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo Nambu-Goldstone Bosons and Goldstini are interesting targets for LHC missing-energy searches.

  17. Dark Mesas of Aram Chaos

    Science.gov (United States)

    2004-01-01

    6 July 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several dark-toned mesas surrounded by light-toned sedimentary rock outcrops in Aram Chaos, a large impact basin -- over 200 km (more than 125 mi) across. These mesas are remnants of a once more extensive rock unit. The image is located near 2.0oN, 20.2oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  18. 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.

  19. Strongly interacting light dark matter

    International Nuclear Information System (INIS)

    Bruggisser, Sebastian; Riva, Francesco; Urbano, Alfredo

    2016-07-01

    In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small-energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo-Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.

  20. light amber and dark amber

    African Journals Online (AJOL)

    Both samples showed high amount of carbohydrate, that of light amber being higher. The antioxidant vitamins (vitamins A, C and E) content of the two honeys are 4.08± 0.21, 2.22± 0.10and 0.28± 0.03(mg/dl), (for light amber), and 4.42± 0.06, 2.61± 0.11,and 0.26± 0.02 (mg/dl), (for dark amber) respectively. Both samples

  1. 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

  2. Microlensing searches of dark matter

    CERN Document Server

    Roulet, Esteban

    2000-01-01

    The evolution of the observational results of microlensing towards the LMC and some of the suggested interpretations to account for them are discussed. It is emphasized that the results at present are indicative of a lensing population of white dwarfs, possibly in the spheroid (not dark halo) of the Galaxy, together with the more standard backgrounds of stellar populations in the Magellanic Clouds and in the Galaxy. This is also hinted by dynamical estimates of the spheroid mass and by recent direct searches of old white dwarfs.

  3. Dark matter searches in ATLAS

    CERN Document Server

    Diehl, Edward; The ATLAS collaboration

    2016-01-01

    Dark matter particles may be produced at the LHC in combination with other particles, typically from initial state radiation. We present results from the ATLAS experiment from searches for phenomena with jets, photons, heavy quarks, electroweak gauge bosons, or Higgs bosons recoiling against large missing transverse momentum. The measurements are interpreted using several theoretical frameworks including simplified models with pair production of Weakly Interacting Massive Particles, effective field theories, and other beyond the Standard Model scenarios. Constraints from dijet searches are compared with results from the “Mono-X” searches to provide a combined interpretation in the context of simplified models.

  4. The cardiovascular benefits of dark chocolate.

    Science.gov (United States)

    Kerimi, Asimina; Williamson, Gary

    2015-08-01

    Dark chocolate contains many biologically active components, such as catechins, procyanidins and theobromine from cocoa, together with added sucrose and lipids. All of these can directly or indirectly affect the cardiovascular system by multiple mechanisms. Intervention studies on healthy and metabolically-dysfunctional volunteers have suggested that cocoa improves blood pressure, platelet aggregation and endothelial function. The effect of chocolate is more convoluted since the sucrose and lipid may transiently and negatively impact on endothelial function, partly through insulin signalling and nitric oxide bioavailability. However, few studies have attempted to dissect out the role of the individual components and have not explored their possible interactions. For intervention studies, the situation is complex since suitable placebos are often not available, and some benefits may only be observed in individuals showing mild metabolic dysfunction. For chocolate, the effects of some of the components, such as sugar and epicatechin on FMD, may oppose each other, or alternatively in some cases may act together, such as theobromine and epicatechin. Although clearly cocoa provides some cardiovascular benefits according to many human intervention studies, the exact components, their interactions and molecular mechanisms are still under debate. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. 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.

  6. Galactic signatures of decaying dark matter

    International Nuclear Information System (INIS)

    Zhang, Le; Sigl, Guenter

    2009-05-01

    If dark matter decays into electrons and positrons, it can affect Galactic radio emissions and the local cosmic ray fluxes. We propose a new, more general analysis of constraints on dark matter. The constraints can be obtained for any decaying dark matter model by convolving the specific dark matter decay spectrum with a response function. We derive this response function from full-sky radio surveys at 408 MHz, 1.42 GHz and 23 GHz, as well as from the positron flux recently reported by PAMELA. We discuss the influence of astrophysical uncertainties on the response function, such as from propagation and from the profiles of the dark matter and the Galactic magnetic field. As an application, we find that some widely used dark matter decay scenarios can be ruled out under modest assumptions. (orig.)

  7. 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.

  8. 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

  9. Gravitational Waves from a Dark Phase Transition.

    Science.gov (United States)

    Schwaller, Pedro

    2015-10-30

    In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early Universe, which could lead to a detectable gravitational wave signal. We summarize the basic conditions for a strong first order phase transition for SU(N) dark sectors with n_{f} flavors, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments. The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors. The discussion includes the twin Higgs and strongly interacting massive particle models as well as symmetric and asymmetric composite dark matter scenarios.

  10. Natural Implementation of Neutralino Dark Matter

    CERN Document Server

    King, S F

    2006-01-01

    The prediction of neutralino dark matter is generally regarded as one of the successes of the Minimal Supersymmetric Standard Model (MSSM). However the successful regions of parameter space allowed by WMAP and collider constraints are quite restricted. We discuss fine-tuning with respect to both dark matter and Electroweak Symmetry Breaking (EWSB) and explore regions of MSSM parameter space with non-universal gaugino and third family scalar masses in which neutralino dark matter may be implemented naturally. In particular allowing non-universal gauginos opens up the bulk region that allows Bino annihilation via t-channel slepton exchange, leading to ``supernatural dark matter'' corresponding to no fine-tuning at all with respect to dark matter. By contrast we find that the recently proposed ``well tempered neutralino'' regions involve substantial fine-tuning of MSSM parameters in order to satisfy the dark matter constraints, although the fine tuning may be ameliorated if several annihilation channels act simu...

  11. Galactic signatures of decaying dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Le; Sigl, Guenter [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Redondo, Javier [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2009-05-15

    If dark matter decays into electrons and positrons, it can affect Galactic radio emissions and the local cosmic ray fluxes. We propose a new, more general analysis of constraints on dark matter. The constraints can be obtained for any decaying dark matter model by convolving the specific dark matter decay spectrum with a response function. We derive this response function from full-sky radio surveys at 408 MHz, 1.42 GHz and 23 GHz, as well as from the positron flux recently reported by PAMELA. We discuss the influence of astrophysical uncertainties on the response function, such as from propagation and from the profiles of the dark matter and the Galactic magnetic field. As an application, we find that some widely used dark matter decay scenarios can be ruled out under modest assumptions. (orig.)

  12. Parallel Universe, Dark Matter and Invisible Higgs Decays

    OpenAIRE

    Chakdar, Shreyashi; Ghosh, Kirtiman; Nandi, S.

    2013-01-01

    The existence of the dark matter with amount about five times the ordinary matter is now well established experimentally. There are now many candidates for this dark matter. However, dark matter could be just like the ordinary matter in a parallel universe. If both universes are described by a non-abelian gauge symmetries, then there will be no kinetic mixing between the ordinary photon and the dark photon, and the dark proton, dark electron and the corresponding dark nuclei, belonging to the...

  13. Dark matter as a cancer hazard

    Directory of Open Access Journals (Sweden)

    Olga Chashchina

    2016-07-01

    Full Text Available We comment on the paper “Dark matter collisions with the human body” by K. Freese and C. Savage (2012 [1] and describe a dark matter model for which the results of the previous paper do not quite apply. Within this mirror dark matter model, potentially hazardous objects, mirror micrometeorites, can exist and may lead to diseases triggered by multiple mutations, such as cancer, though with very low probability.

  14. 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.

  15. Interacting holographic dark energy with logarithmic correction

    OpenAIRE

    Jamil, Mubasher; Farooq, M. Umar

    2010-01-01

    The holographic dark energy (HDE) is considered to be the most promising candidate of dark energy. Its definition is originally motivated from the entropy-area relation which depends on the theory of gravity under consideration. Recently a new definition of HDE is proposed with the help of quantum corrections to the entropy-area relation in the setup of loop quantum cosmology. Using this new definition, we investigate the model of interacting dark energy and derive its effective equation of s...

  16. Tiny galaxies help unravel dark matter mystery

    CERN Multimedia

    O'Hanlon, Larry

    2007-01-01

    "The 70-year effort to unravel the mysteries of dark matter just got a big boost from some very puny galaxies. In the pas few years, a score of dwarf galaxies have been discovered hanging about the fringes of the Milky way. Now new measurements of the few stars int hese dwarfs reveal them to be dark mater distilleries, with upwards of 1'000 times more dark than normal matter." (3 pages)

  17. Surrogate Models for Direct Dark Matter Detection

    OpenAIRE

    Cerdeno, D. G.; Cheek, A.; Reid, E.; Schulz, H.

    2018-01-01

    In this work we introduce RAPIDD, a surrogate model that speeds up the computation of the expected spectrum of dark matter particles in direct detection experiments. RAPIDD replaces the exact calculation of the dark matter differential rate (which in general involves up to three nested integrals) with a much faster parametrization in terms of ordinary polynomials of the dark matter mass and couplings, obtained in an initial training phase. In this article, we validate our surrogate model on t...

  18. Galaxy Structure, Dark Matter, and Galaxy Formation

    OpenAIRE

    Weinberg, David H.

    1996-01-01

    The structure of galaxies, the nature of dark matter, and the physics of galaxy formation were the interlocking themes of DM 1996: Dark and Visible Matter in Galaxies and Cosmological Implications. In this conference summary report, I review recent observational and theoretical advances in these areas, then describe highlights of the meeting and discuss their implications. I include as an appendix the lyrics of The Dark Matter Rap: A Cosmological History for the MTV Generation.

  19. Dark Matter Universal Properties in Galaxies

    International Nuclear Information System (INIS)

    Frigerio Martins, Christiane

    2011-01-01

    In the past years a wealth of observations has unraveled the structural properties of dark and luminous mass distribution in galaxies, a benchmark for understanding dark matter and the process of galaxy formation. The study of the kinematics of over thousand spirals has evidenced a dark-luminous matter coupling and the presence of a series of scaling laws, pictured by the Universal Rotation Curve paradigm, an intriguing observational scenario not easily explained by present theories of galaxy formation.

  20. Dark Matter Universal Properties in Galaxies

    OpenAIRE

    Martins, Christiane Frigerio

    2010-01-01

    In the past years a wealth of observations has unraveled the structural properties of dark and luminous mass distribution in galaxies, a benchmark for understanding dark matter and the process of galaxy formation. The study of the kinematics of over thousand spirals has evidenced a dark-luminous matter coupling and the presence of a series of scaling laws, pictured by the Universal Rotation Curve paradigm, an intriguing observational scenario not easily explained by present theories of galaxy...

  1. Dark and visible matter in spiral galaxies

    International Nuclear Information System (INIS)

    Persic, M.; Salucci, P.; Durham Univ.

    1988-01-01

    Exploiting relevant information from the profiles of rotation curves, we calculate the dark-to-luminous mass ratio within the disc size for a sample of 43 spiral galaxies. The values we find, while proving the ubiquitous presence of dark matter, vary with luminosity. Faint and bright galaxies are found to be respectively halo- and disc-dominated in the disc regions. The luminosity sequence turns out to be a dark-to-luminous sequence. (author)

  2. Axion: Mass -- Dark Matter Abundance Relation

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The axion is a hypothetical particle which would explain why QCD is approximately T-conserving, and is also an excellent Cold Dark Matter candidate. It should be possible to make a clean theoretical prediction relating the dark matter density in axions and the axion mass (under reasonable assumptions about inflation). But the axion's early-Universe dynamics, which establish its density as dark matter, are unexpectedly rich in a way which is only starting to yield to quantitative numerical study.

  3. 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.

  4. Blood typing

    Science.gov (United States)

    Blood typing is a method to tell what type of blood you have. Blood typing is done so you can safely donate your blood or receive a blood transfusion. It is also done to see if you have a substance called Rh factor on the surface of your red ...

  5. Blood Types

    Science.gov (United States)

    ... KidsHealth / For Teens / Blood Types What's in this article? Four Blood Groups... Plus Rh Factor... ...Make Eight Blood Types Why Blood Type Matters Print en español Tipos de sangre About 5 million Americans need blood transfusions every ...

  6. How clustering dark energy affects matter perturbations

    Science.gov (United States)

    Mehrabi, A.; Basilakos, S.; Pace, F.

    2015-09-01

    The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed c2_eff and for c2_eff=0 dark energy clusters in a similar fashion to dark matter while for c2_eff=1 it stays (approximately) homogeneous. In this paper we consider two distinct equations of state for the dark energy component, wd = const and w_d=w_0+w_1(z/1+z) with c2_eff as a free parameter and we try to constrain the dark energy effective sound speed using current available data including Type Ia supernovae, baryon acoustic oscillation, cosmic microwave background shift parameter (Planck and WMAP), Hubble parameter, big bang nucleosynthesis and the growth rate of structures fσ8(z). At first we derive the most general form of the equations governing dark matter and dark energy clustering under the assumption that c2_eff=const. Finally, performing an overall likelihood analysis we find that the likelihood function peaks at c2_eff=0; however, the dark energy sound speed is degenerate with respect to the cosmological parameters, namely Ωm and wd.

  7. Baryonic and Non-Baryonic Dark Matter

    OpenAIRE

    Carr, Bernard

    2000-01-01

    Cosmological nucleosynthesis calculations imply that there should be both non-baryonic and baryonic dark matter. Recent data suggest that some of the non-baryonic dark matter must be "hot" (i.e. massive neutrinos) and there may also be evidence for "cold" dark matter (i.e. WIMPs). If the baryonic dark matter resides in galactic halos, it is likely to be in the form of compact objects (i.e. MACHOs) and these would probably be the remnants of a first generation of pregalactic or protogalactic P...

  8. Unbound particles in dark matter halos

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, Peter S.; Loeb, Abraham; Wechsler, Risa H.

    2013-06-13

    We investigate unbound dark matter particles in halos by tracing particle trajectories in a simulation run to the far future (a = 100). We find that the traditional sum of kinetic and potential energies is a very poor predictor of which dark matter particles will eventually become unbound from halos. We also study the mass fraction of unbound particles, which increases strongly towards the edges of halos, and decreases significantly at higher redshifts. We discuss implications for dark matter detection experiments, precision calibrations of the halo mass function, the use of baryon fractions to constrain dark energy, and searches for intergalactic supernovae.

  9. 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.

  10. Flavored dark matter beyond Minimal Flavor Violation

    CERN Document Server

    Agrawal, Prateek; Gemmler, Katrin

    2014-10-13

    We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a $U(3)_\\chi$ associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter $\\chi$ which transforms as triplet under $U(3)_\\chi$, and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator $\\phi$ with a coupling $\\lambda$. We identify a number of "flavor-safe" scenarios for the structure of $\\lambda$ which are beyond Minimal Flavor Violation. For dark matter and collider phenomenology we focus on the well-motivated case of $b$-...

  11. Atomki anomaly and the Secluded Dark Sector

    OpenAIRE

    Yamamoto Yasuhiro

    2018-01-01

    The Atomiki anomaly can be interpreted as a new light vector boson. If such a new particle exists, it could be a mediator between the Standard Model sector and the dark sector including the dark matter. We discussed some simple effective models with these particles. In the models, the secluded dark matter models are good candidates to satisfy the thermal relic abundance. In particular, we found that the dark matter self-interaction can be large enough to solve the small scale structure puzzle...

  12. Sterile neutrino dark matter with supersymmetry

    Science.gov (United States)

    Shakya, Bibhushan; Wells, James D.

    2017-08-01

    Sterile neutrino dark matter, a popular alternative to the WIMP paradigm, has generally been studied in non-supersymmetric setups. If the underlying theory is supersymmetric, we find that several interesting and novel dark matter features can arise. In particular, in scenarios of freeze-in production of sterile neutrino dark matter, its superpartner, the sterile sneutrino, can play a crucial role in early Universe cosmology as the dominant source of cold, warm, or hot dark matter, or of a subdominant relativistic population of sterile neutrinos that can contribute to the effective number of relativistic degrees of freedom Neff during big bang nucleosynthesis.

  13. Intrinsic entropy perturbations from the dark sector

    Science.gov (United States)

    Celoria, Marco; Comelli, Denis; Pilo, Luigi

    2018-03-01

    Perfect fluids are modeled by using an effective field theory approach which naturally gives a self-consistent and unambiguous description of the intrinsic non-adiabatic contribution to pressure variations. We study the impact of intrinsic entropy perturbation on the superhorizon dynamics of the curvature perturbation Script R in the dark sector. The dark sector, made of dark matter and dark energy is described as a single perfect fluid. The non-perturbative vorticity's dynamics and the Weinberg theorem violation for perfect fluids are also studied.

  14. How cold is cold dark matter?

    International Nuclear Information System (INIS)

    Armendariz-Picon, Cristian; Neelakanta, Jayanth T.

    2014-01-01

    If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed

  15. Dark Matter Coannihilation with a Lighter Species.

    Science.gov (United States)

    Berlin, Asher

    2017-09-22

    We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, M_{GUT}∼10^{16}  GeV.

  16. Direct Dark Matter Searches: Status and Perspectives

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    There is overwhelming indirect evidence that dark matter exists, however, the dark matter particle has not yet been directly detected in laboratory experiments. In order to be able to identify the rare dark matter interactions with the target nuclei, such instruments have to feature a very low threshold and an extremely low radioactive background. They are therefore installed in underground laboratories to reduce cosmic ray backgrounds. I will review the status of direct dark matter searches and will discuss the perspectives for the future.

  17. Dipolar dark matter with massive bigravity

    International Nuclear Information System (INIS)

    Blanchet, Luc; Heisenberg, Lavinia

    2015-01-01

    Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because of the particular couplings of the matter fields and vector field to the metrics, a ghost in the decoupling limit is present in the dark matter sector. However, it might be possible to push the mass of the ghost beyond the strong coupling scale by an appropriate choice of the parameters of the model. Crucial questions to address in future work are the exact mass of the ghost, and the cosmological implications of the model

  18. 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

  19. Entropy-Corrected Holographic Dark Energy

    International Nuclear Information System (INIS)

    Wei Hao

    2009-01-01

    The holographic dark energy (HDE) is now an interesting candidate of dark energy, which has been studied extensively in the literature. In the derivation of HDE, the black hole entropy plays an important role. In fact, the entropy-area relation can be modified due to loop quantum gravity or other reasons. With the modified entropy-area relation, we propose the so-called 'entropy-corrected holographic dark energy' (ECHDE) in the present work. We consider many aspects of ECHDE and find some interesting results. In addition, we briefly consider the so-called 'entropy-corrected agegraphic dark energy' (ECADE). (geophysics, astronomy, and astrophysics)

  20. Interacting holographic dark energy with logarithmic correction

    International Nuclear Information System (INIS)

    Jamil, Mubasher; Farooq, M. Umar

    2010-01-01

    The holographic dark energy (HDE) is considered to be the most promising candidate of dark energy. Its definition is motivated from the entropy-area relation which depends on the theory of gravity under consideration. Recently a new definition of HDE is proposed with the help of quantum corrections to the entropy-area relation in the setup of loop quantum cosmology. Employing this new definition, we investigate the model of interacting dark energy and derive its effective equation of state. Finally we establish a correspondence between generalized Chaplygin gas and entropy-corrected holographic dark energy

  1. DAMIC: a novel dark matter experiment

    Energy Technology Data Exchange (ETDEWEB)

    Tiffenberg, Javier; Bertou, Xavier [Centro Atomico Bariloche; Butner, Melissa J. [Fermilab; Cancelo, Gustavo [Fermilab; Chavarria, Alvaro [Chicago U., KICP; D' Olivo, Juan Carlos [Mexico U., ICN; Estrada Vigil, Juan Cruz [Fermilab; Moroni, Guillermo Fernandez [Bahia Blanca, U. Natl. Del Sur; Izraelevitch, Federico [Fermilab; Kilminster, Ben [Zurich U.; Lawson, Ian T. [SNOLAB, Lively; Marsal, Fernando [Asuncion Natl. U.; Molina, Jorge [Asuncion Natl. U.; Privitera, Paolo [Chicago U., KICP; Schwarz, Tom [Michigan U.; Sofo haro, Miguel [Centro Atomico Bariloche; Tiffenberg, Javier [Fermilab; Trillaud, Frederic [Mexico U.; Zhou, Jing [Chicago U., KICP

    2013-10-24

    DAMIC (Dark Matter in CCDs) is a novel dark matter experiment that has unique sensitivity to dark matter particles with masses below 10 GeV. Due to its low electronic readout noise (R.M.S. ~3 e-) this instrument is able to reach a detection threshold below 0.5 keV nuclear recoil energy, making the search for dark matter particles with low masses possible. We report on early results and experience gained from a detector that has been running at SNOLAB from Dec 2012. We also discuss the measured and expected backgrounds and present the plan for future detectors to be installed in 2014.

  2. The Quest for Dark Matter

    CERN Document Server

    Rubbia, Carlo

    2005-01-01

    Recent experiments have brought for the first time under a strong experimental basis that the total density of the Universe is Wo = 1.02 ± 0.02. We have for the first time a cosmic agreement, namely matter density WM = 0.27 ± 0.04 and dark energy density WL = 0.73 ± 0.04 add up precisely to Wo ! WM + WL. On the other hand ordinary hadronic matter (quarks and leptons) determined by the Big Bang Nucleo-synthesis (BBN) is also firmly set to WBBN = 0.044 ± 0.004. About 100 years after Einstein's birth we know experimentally the identity of less than 5% of what the Universe is made of, the remaining > 95% escaping to us completely. An enormous effort is being made at LHC in order to discover SUSY particles. SUSY is an “almost necessity” of elementary particle physics. The fact that such particles may also account for the observed non baryonic dark matter is either a big coincidence or a big hint. If such SUSY particles indeed exist, they must have been...

  3. Dark matter and galaxy formation

    International Nuclear Information System (INIS)

    Umemura, Masayuki

    1987-01-01

    We propose a hybrid model of universe for galaxy formation, that is, an Einstein- de Sitter universe dominated by two-component dark matter: massive neutrinos and cold dark matter. In this hybrid model, the first luminous objects are dwarf galaxies. The neutrino density fluctuations produce large-scale high density and low density regions, which consequently evolve to superclusters of galaxies and voids, respectively. Dwarf galaxies are formed preferentially in supercluster regions. In voids, the formation of dwarf galaxies is fairly suppressed by diffuse UV flux from QSOs, and instead a number of expanding clouds are born, which produce Lyα forest as seen in QSO spectra. Ordinary galaxies are expected to form as aggregations of dwarf galaxies. In this model, some galaxies are born also in voids, and they tend to evolve to spiral galaxies. Additionally, if the same number of globular clusters are formed in a dwarf, the specific globular cluster frequencies are expected to be much larger in ellipticals than in spirals. (author)

  4. Phenomenology of 1032 dark sectors

    International Nuclear Information System (INIS)

    Dvali, Gia; Redi, Michele

    2009-01-01

    We postulate an exact permutation symmetry acting on 10 32 standard model copies as the largest possible symmetry extension of the standard model. This setup automatically lowers the fundamental gravity cutoff down to TeV, and thus, accounts for the quantum stability of the weak scale. We study the phenomenology of this framework and show that below TeV energies the copies are well hidden, obeying all the existing observational bounds. Nevertheless, we identify a potential low energy window into the hidden world, the oscillation of the neutron into its dark copies. At the same time, proton decay can be suppressed by gauging the diagonal baryon number of the different copies. This framework offers an alternative approach to several particle physics questions. For example, we suggest a novel mechanism for generating naturally small neutrino masses that are suppressed by the number of neutrino species. The mirror copies of the standard model naturally house dark matter candidates. The general experimentally observable prediction of this scenario is an emergence of strong gravitational effects at the LHC. The low energy permutation symmetry powerfully constrains the form of this new gravitational physics and allows to make observational predictions, such as, production of micro black holes with very peculiar properties.

  5. 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

  6. DarkSUSY 6 : An Advanced Tool to Compute Dark Matter Properties Numerically

    OpenAIRE

    Bringmann, Torsten; Edsjo, Joakim; Gondolo, Paolo; Ullio, Piero; Bergstrom, Lars

    2018-01-01

    The nature of dark matter remains one of the key science questions. Weakly Interacting Massive Particles (WIMPs) are among the best motivated particle physics candidates, allowing to explain the measured dark matter density by employing standard big-bang thermodynamics. Examples include the lightest supersymmetric particle, though many alternative particles have been suggested as a solution to the dark matter puzzle. We introduce here a radically new version of the widely used DarkSUSY packag...

  7. 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.

  8. 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...

  9. Hidden charged dark matter and chiral dark radiation

    Science.gov (United States)

    Ko, P.; Nagata, Natsumi; Tang, Yong

    2017-10-01

    In the light of recent possible tensions in the Hubble constant H0 and the structure growth rate σ8 between the Planck and other measurements, we investigate a hidden-charged dark matter (DM) model where DM interacts with hidden chiral fermions, which are charged under the hidden SU(N) and U(1) gauge interactions. The symmetries in this model assure these fermions to be massless. The DM in this model, which is a Dirac fermion and singlet under the hidden SU(N), is also assumed to be charged under the U(1) gauge symmetry, through which it can interact with the chiral fermions. Below the confinement scale of SU(N), the hidden quark condensate spontaneously breaks the U(1) gauge symmetry such that there remains a discrete symmetry, which accounts for the stability of DM. This condensate also breaks a flavor symmetry in this model and Nambu-Goldstone bosons associated with this flavor symmetry appear below the confinement scale. The hidden U(1) gauge boson and hidden quarks/Nambu-Goldstone bosons are components of dark radiation (DR) above/below the confinement scale. These light fields increase the effective number of neutrinos by δNeff ≃ 0.59 above the confinement scale for N = 2, resolving the tension in the measurements of the Hubble constant by Planck and Hubble Space Telescope if the confinement scale is ≲1 eV. DM and DR continuously scatter with each other via the hidden U(1) gauge interaction, which suppresses the matter power spectrum and results in a smaller structure growth rate. The DM sector couples to the Standard Model sector through the exchange of a real singlet scalar mixing with the Higgs boson, which makes it possible to probe our model in DM direct detection experiments. Variants of this model are also discussed, which may offer alternative ways to investigate this scenario.

  10. Dark Energy: The Shadowy Reflection of Dark Matter?

    Directory of Open Access Journals (Sweden)

    Kostas Kleidis

    2016-03-01

    Full Text Available In this article, we review a series of recent theoretical results regarding a conventional approach to the dark energy (DE concept. This approach is distinguished among others for its simplicity and its physical relevance. By compromising General Relativity (GR and Thermodynamics at cosmological scale, we end up with a model without DE. Instead, the Universe we are proposing is filled with a perfect fluid of self-interacting dark matter (DM, the volume elements of which perform hydrodynamic flows. To the best of our knowledge, it is the first time in a cosmological framework that the energy of the cosmic fluid internal motions is also taken into account as a source of the universal gravitational field. As we demonstrate, this form of energy may compensate for the DE needed to compromise spatial flatness, while, depending on the particular type of thermodynamic processes occurring in the interior of the DM fluid (isothermal or polytropic, the Universe depicts itself as either decelerating or accelerating (respectively. In both cases, there is no disagreement between observations and the theoretical prediction of the distant supernovae (SNe Type Ia distribution. In fact, the cosmological model with matter content in the form of a thermodynamically-involved DM fluid not only interprets the observational data associated with the recent history of Universe expansion, but also confronts successfully with every major cosmological issue (such as the age and the coincidence problems. In this way, depending on the type of thermodynamic processes in it, such a model may serve either for a conventional DE cosmology or for a viable alternative one.

  11. Dark matter model with non-Abelian gauge symmetry

    International Nuclear Information System (INIS)

    Zhang Hao; Li Chongsheng; Cao Qinghong; Li Zhao

    2010-01-01

    We propose a dark-matter model in which the dark sector is gauged under a new SU(2) group. The dark sector consists of SU(2) dark gauge fields, two triplet dark Higgs fields, and two dark fermion doublets (dark-matter candidates in this model). The dark sector interacts with the standard model sector through kinetic and mass mixing operators. The model explains both PAMELA and Fermi LAT data very well and also satisfies constraints from both the dark-matter relic density and standard model precision observables. The phenomenology of the model at the LHC is also explored.

  12. 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

  13. A New Dark Vortex on Neptune

    Science.gov (United States)

    Wong, Michael H.; Tollefson, Joshua; Hsu, Andrew I.; de Pater, Imke; Simon, Amy A.; Hueso, Ricardo; Sánchez-Lavega, Agustín; Sromovsky, Lawrence; Fry, Patrick; Luszcz-Cook, Statia; Hammel, Heidi; Delcroix, Marc; de Kleer, Katherine; Orton, Glenn S.; Baranec, Christoph

    2018-03-01

    An outburst of cloud activity on Neptune in 2015 led to speculation about whether the clouds were convective in nature, a wave phenomenon, or bright companions to an unseen dark vortex (similar to the Great Dark Spot studied in detail by Voyager 2). The Hubble Space Telescope (HST) finally answered this question by discovering a new dark vortex at 45 degrees south planetographic latitude, named SDS-2015 for “southern dark spot discovered in 2015.” SDS-2015 is only the fifth dark vortex ever seen on Neptune. In this paper, we report on imaging of SDS-2015 using HST’s Wide Field Camera 3 across four epochs: 2015 September, 2016 May, 2016 October, and 2017 October. We find that the size of SDS-2015 did not exceed 20 degrees of longitude, more than a factor of two smaller than the Voyager dark spots, but only slightly smaller than previous northern-hemisphere dark spots. A slow (1.7–2.5 deg/year) poleward drift was observed for the vortex. Properties of SDS-2015 and its surroundings suggest that the meridional wind shear may be twice as strong at the deep level of the vortex as it is at the level of cloud-tracked winds. Over the 2015–2017 period, the dark spot’s contrast weakened from about -7 % to about -3 % , while companion clouds shifted from offset to centered, a similar evolution to some historical dark spots. The properties and evolution of SDS-2015 highlight the diversity of Neptune’s dark spots and the need for faster cadence dark spot observations in the future.

  14. 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.)

  15. 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.

  16. Relic abundance of mass-varying cold dark matter particles

    International Nuclear Information System (INIS)

    Rosenfeld, Rogerio

    2005-01-01

    In models of coupled dark energy and dark matter the mass of the dark matter particle depends on the cosmological evolution of the dark energy field. In this Letter we exemplify in a simple model the effects of this mass variation on the relic abundance of cold dark matter

  17. Evolution of holographic dark energy with interaction term Q ...

    Indian Academy of Sciences (India)

    Abstract. A flat FLRW Universe with dark matter and dark energy, which are interacting with each other, is considered. The dark energy is represented by the holographic dark energy model and the interaction term is taken as proportional to the dark energy density. We have studied the cosmological evolution and analysed ...

  18. Types of Blood Donations

    Science.gov (United States)

    ... ill patients. Blood Donation 101 Blood Donation FAQs Types of Blood Donations The Foundation for America's Blood Centers Donate Blood Blood Donation 101 Blood Donation FAQs Types of Blood Donations About Blood What is Blood? ...

  19. Acute dark chocolate ingestion is beneficial for hemodynamics via enhancement of erythrocyte deformability in healthy humans.

    Science.gov (United States)

    Radosinska, Jana; Horvathova, Martina; Frimmel, Karel; Muchova, Jana; Vidosovicova, Maria; Vazan, Rastislav; Bernatova, Iveta

    2017-03-01

    Erythrocyte deformability is an important property of erythrocytes that considerably affects blood flow and hemodynamics. The high content of polyphenols present in dark chocolate has been reported to play a protective role in functionality of erythrocytes. We hypothesized that chocolate might influence erythrocytes not only after repeated chronic intake, but also immediately after its ingestion. Thus, we determined the acute effect of dark chocolate and milk (with lower content of biologically active substances) chocolate intake on erythrocyte deformability. We also focused on selected factors that may affect erythrocyte deformability, specifically nitric oxide production in erythrocytes and total antioxidant capacity of plasma. We determined posttreatment changes in the mentioned parameters 2hours after consumption of chocolate compared with their levels before consumption of chocolate. In contrast to milk chocolate intake, the dark chocolate led to a significantly higher increase in erythrocyte deformability. Nitric oxide production in erythrocytes was not changed after dark chocolate intake, but significantly decreased after milk chocolate. The plasma total antioxidant capacity remained unaffected after ingestion of both chocolates. We conclude that our hypothesis was confirmed. Single ingestion of dark chocolate improved erythrocyte deformability despite unchanged nitric oxide production and antioxidant capacity of plasma. Increased deformability of erythrocytes may considerably improve rheological properties of blood and thus hemodynamics in humans, resulting in better tissue oxygenation. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Dynamic array of dark optical traps

    DEFF Research Database (Denmark)

    Daria, V.R.; Rodrigo, P.J.; Glückstad, J.

    2004-01-01

    A dynamic array of dark optical traps is generated for simultaneous trapping and arbitrary manipulation of multiple low-index microstructures. The dynamic intensity patterns forming the dark optical trap arrays are generated using a nearly loss-less phase-to-intensity conversion of a phase-encode...

  1. Nonthermal axion dark radiation and constraints

    NARCIS (Netherlands)

    Mazumdar, Anupam; Qutub, Saleh; Saikawa, Ken'ichi

    2016-01-01

    The Peccei-Quinn mechanism presents a neat solution to the strong C P problem. As a by-product, it provides an ideal dark matter candidate, "the axion", albeit with a tiny mass. Axions therefore can act as dark radiation if excited with large momenta after the end of inflation. Nevertheless, the

  2. Dark Current Reduction of IR Detectors

    Science.gov (United States)

    2017-10-19

    extremely high dark currents, exhibited increased dark current with the contact anneal, and do not vary with junction area. All of these symptoms are...2 2.1 - Motivation ........................................................................................................................... 2 3...on this program. It has been an invaluable experience for both Prof. Bellotti and his students , whom have been able to gain a substantial amount of

  3. The Dark Triad across academic majors

    DEFF Research Database (Denmark)

    Vedel, Anna; Thomsen, Dorthe K.

    2017-01-01

    The Dark Triad traits (i.e., narcissism, psychopathy, and Machiavellianism) have been associated with the desire for power, status, and social dominance in the workplace, and these desires have been hypothesized to draw Dark Triad individuals towards occupations affording such outcomes. Following...

  4. Collision of Bose Condensate Dark Matter structures

    International Nuclear Information System (INIS)

    Guzman, F. S.

    2008-01-01

    The status of the scalar field or Bose condensate dark matter model is presented. Results about the solitonic behavior in collision of structures is presented as a possible explanation to the recent-possibly-solitonic behavior in the bullet cluster merger. Some estimates about the possibility to simulate the bullet cluster under the Bose Condensate dark matter model are indicated.

  5. Intergalactic medium heating by dark matter

    NARCIS (Netherlands)

    Ripamonti, E.; Mapelli, M.; Ferrara, A.

    2006-01-01

    Abstract: We derive the evolution of the energy deposition in the intergalactic medium (IGM) by dark matter (DM) decays/annihilations for both sterile neutrinos and light dark matter (LDM) particles. At z > 200 sterile neutrinos transfer a fraction f_abs~0.5 of their rest mass energy into the IGM;

  6. Natural implementation of neutralino dark matter

    International Nuclear Information System (INIS)

    King, Steve F.; Roberts, Jonathan P.

    2006-01-01

    The prediction of neutralino dark matter is generally regarded as one of the successes of the Minimal Supersymmetric Standard Model (MSSM). However the successful regions of parameter space allowed by WMAP and collider constraints are quite restricted. We discuss fine-tuning with respect to both dark matter and Electroweak Symmetry Breaking (EWSB) and explore regions of MSSM parameter space with non-universal gaugino and third family scalar masses in which neutralino dark matter may be implemented naturally. In particular allowing non-universal gauginos opens up the bulk region that allows Bino annihilation via t-channel slepton exchange, leading to 'supernatural dark matter' corresponding to no fine-tuning at all with respect to dark matter. By contrast we find that the recently proposed 'well tempered neutralino' regions involve substantial fine-tuning of MSSM parameters in order to satisfy the dark matter constraints, although the fine tuning may be ameliorated if several annihilation channels act simultaneously. Although we have identified regions of 'supernatural dark matter' in which there is no fine tuning to achieve successful dark matter, the usual MSSM fine tuning to achieve EWSB always remains

  7. Dark degeneracy and interacting cosmic components

    International Nuclear Information System (INIS)

    Aviles, Alejandro; Cervantes-Cota, Jorge L.

    2011-01-01

    We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy-momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy) is arbitrary. In fact, just one dark fluid is necessary to obtain exactly the same cosmological and astrophysical phenomenology as the ΛCDM model. We work explicitly the first-order perturbation theory and show that beyond the linear order the dark degeneracy is preserved under some general assumptions. Then we construct the dark fluid from a collection of interacting fluids. Finally, we try to break the degeneracy with a general class of couplings to baryonic matter. Nonetheless, we show that these interactions can also be understood in the context of the ΛCDM model as between dark matter and baryons. For this last investigation we choose two independent parametrizations for the interactions, one inspired by electromagnetism and the other by chameleon theories. Then, we constrain them with a joint analysis of CMB and supernovae observational data.

  8. Interacting Dark Energy Models and Observations

    Science.gov (United States)

    Shojaei, Hamed; Urioste, Jazmin

    2017-01-01

    Dark energy is one of the mysteries of the twenty first century. Although there are candidates resembling some features of dark energy, there is no single model describing all the properties of dark energy. Dark energy is believed to be the most dominant component of the cosmic inventory, but a lot of models do not consider any interaction between dark energy and other constituents of the cosmic inventory. Introducing an interaction will change the equation governing the behavior of dark energy and matter and creates new ways to explain cosmic coincidence problem. In this work we studied how the Hubble parameter and density parameters evolve with time in the presence of certain types of interaction. The interaction serves as a way to convert dark energy into matter to avoid a dark energy-dominated universe by creating new equilibrium points for the differential equations. Then we will use numerical analysis to predict the values of distance moduli at different redshifts and compare them to the values for the distance moduli obtained by WMAP (Wilkinson Microwave Anisotropy Probe). Undergraduate Student

  9. Observation of attraction between dark solitons

    DEFF Research Database (Denmark)

    Dreischuh, A.; Neshev, D.N.; Petersen, D.E.

    2006-01-01

    We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems...

  10. Attraction of nonlocal dark optical solitons

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov; Neshev, Dragomir; Krolikowski, Wieslaw

    2004-01-01

    We study the formation and interaction of spatial dark optical solitons in materials with a nonlocal nonlinear response. We show that unlike in local materials, where dark solitons typically repel, the nonlocal nonlinearity leads to a long-range attraction and formation of stable bound states...

  11. Searching a dark photon with HADES

    Czech Academy of Sciences Publication Activity Database

    Agakishiev, G.; Balanda, A.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Boyard, J. L.; Cabanelas, P.; Chernenko, S.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Krása, Antonín; Křížek, Filip; Kugler, Andrej; Sobolev, Yuri, G.; Tlustý, Pavel; Wagner, Vladimír

    2014-01-01

    Roč. 731, APR (2014), s. 265-271 ISSN 0370-2693 R&D Projects: GA ČR GA13-06759S; GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : HADES * dark photon * hidden sector * dark matter * rare eta decays Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 6.131, year: 2014

  12. Formation of multiple dark photovoltaic spatial solitons

    Indian Academy of Sciences (India)

    Abstract. We theoretically study the formation of multiple dark photovoltaic soliton splitting in the quasi-steady-state and steady-state regimes under open-circuit conditions. We find that the initial width of the dark notch at the entrance face of the crystal is a key parameter for generating an even (or odd) number sequence of ...

  13. Z{sub 2} SIMP dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Nicolás [ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo (Brazil); Chu, Xiaoyong, E-mail: nicolas@ift.unesp.br, E-mail: xchu@ictp.it [ICTP International Centre for Theoretical Physics Strada Costiera 11, 34014 Trieste (Italy)

    2016-01-01

    Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a Z{sub 2} symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model.

  14. ℤ{sub 2} SIMP dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Nicolás [ICTP South American Institute for Fundamental Research,Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo (Brazil); Chu, Xiaoyong [ICTP International Centre for Theoretical PhysicsStrada Costiera 11, 34014 Trieste (Italy)

    2016-01-05

    Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N{sup ′} processes, where N dark matter particles annihilate to N{sup ′} of them. In the most common scenarios, where dark matter stability is guaranteed by a ℤ{sub 2} symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model.

  15. Anomalous dark growth rings in black cherry

    Science.gov (United States)

    Robert P. Long; David W. Trimpey; Michael C. Wiemann; Susan L. Stout

    2012-01-01

    Anomalous dark growth rings have been observed in black cherry (Prunus serotina) sawlogs from northwestern Pennsylvania making the logs unsuitable for veneer products. Thirty-six cross sections with dark rings, each traceable to one of ten stands, were obtained from a local mill and sections were dated and annual ring widths were measured. One or...

  16. Dark matter and galactic cosmic rays

    International Nuclear Information System (INIS)

    Taillet, R.

    2010-12-01

    Dark matter is one of the major problems encountered by modern cosmology and astrophysics, resisting the efforts of both theoreticians and experimentalists. The problem itself is easy to state: many indirect astrophysical measurements indicate that the mass contained in the Universe seems to be dominated by a new type of matter which has never been directly seen yet, this is why it is called dark matter. This hypothesis of dark matter being made of new particles is of great interest for particle physicists, whose theories provide many candidates: dark matter is one of the major topics of astro-particle physics. This work focuses on searching dark matter in the form of new particles, more precisely to indirect detection, i.e. the search of particles produced by dark matter annihilation rather than dark matter particles themselves. In this framework, I will present the studies I have been doing in the field of cosmic rays physics (particularly cosmic ray sources), in several collaborations. In particular, the study of the antimatter component of cosmic rays can give relevant information about dark matter. The last chapter is dedicated to my teaching activities

  17. Review of dark matter direct detection experiments

    Indian Academy of Sciences (India)

    Matter, as we know it, makes up less than 5% of the Universe. Various astrophysical observations have confirmed that one quarter of the Universe and most of the matter content in the Universe is made up of dark matter. The nature of dark matter is yet to be discovered and is one of the biggest questions in physics. Particle ...

  18. Intergalactic medium heating by dark matter

    NARCIS (Netherlands)

    Ripamonti, E.; Mapelli, M.; Ferrara, A.

    2007-01-01

    We derive the evolution of the energy deposition in the intergalactic medium (IGM) by dark matter (DM) decays/annihilations for both sterile neutrinos and light dark matter (LDM) particles. At z > 200 sterile neutrinos transfer a fraction f(abs) similar to 0.5 of their rest mass energy into the IGM;

  19. Natural implementation of neutralino dark matter

    Science.gov (United States)

    King, Steve F.; Roberts, Jonathan P.

    2006-09-01

    The prediction of neutralino dark matter is generally regarded as one of the successes of the Minimal Supersymmetric Standard Model (MSSM). However the successful regions of parameter space allowed by WMAP and collider constraints are quite restricted. We discuss fine-tuning with respect to both dark matter and Electroweak Symmetry Breaking (EWSB) and explore regions of MSSM parameter space with non-universal gaugino and third family scalar masses in which neutralino dark matter may be implemented naturally. In particular allowing non-universal gauginos opens up the bulk region that allows Bino annihilation via t-channel slepton exchange, leading to ``supernatural dark matter'' corresponding to no fine-tuning at all with respect to dark matter. By contrast we find that the recently proposed ``well tempered neutralino'' regions involve substantial fine-tuning of MSSM parameters in order to satisfy the dark matter constraints, although the fine tuning may be ameliorated if several annihilation channels act simultaneously. Although we have identified regions of ``supernatural dark matter'' in which there is no fine tuning to achieve successful dark matter, the usual MSSM fine tuning to achieve EWSB always remains.

  20. Observational consequences of a dark interaction model

    Energy Technology Data Exchange (ETDEWEB)

    Campos, M. de, E-mail: campos@if.uff.b [Roraima Federal University (UFRR), Paricarana, Boa Vista, RO (Brazil). Physics Dept.

    2010-12-15

    We study a model with decay of dark energy and creation of the dark matter particles. We integrate the field equations and find the transition redshift where the evolution process of the universe change the accelerated expansion, and discuss the luminosity distance, acoustic oscillations and the state finder parameters. (author)

  1. Corrigendum: 'Anomalous Kolar events revisited: Dark matter?'

    Indian Academy of Sciences (India)

    2017-03-08

    Mar 8, 2017 ... problems in one stroke, namely the explanation of the. Kolar events as well as the observation of dark matter particles in laboratory conditions. In the meantime, the authors have become aware of some limits on the lifetime of decaying dark matter due to the data from Fermi LAT observations of the extra-.

  2. Dark photons from nuclear transitions

    Science.gov (United States)

    Kozaczuk, Jonathan

    2018-01-01

    Light new particles can be emitted in decays of excited nuclear states. Experiments analyzing such transitions and incorporating high-resolution detectors can be sensitive to new MeV-scale physics at a level competitive with upcoming collider and other fixed target experiments, provided sufficient luminosity. We demonstrate this in the case of the Be 8 system, showing that searches targeting the reported anomaly in Be 8 nuclear transitions can also be sensitive to currently unexplored regions of the canonical dark photon parameter space with 1 MeV ≲mA'≲18 MeV and ɛ2≳10-7 . These experiments could be performed on a short time scale, at low cost, and directly probe both the hadronic and leptonic couplings of light hidden particles.

  3. The dark side of technology

    CERN Document Server

    Townsend, Peter

    2016-01-01

    Technological progress comes with a dark side where good ideas and intentions produce undesirable results (extreme downsides include atomic and biological weapons). The many and various unexpected outcomes of technology span humorous to bizarre, to situations that threaten human survival. Development can be positive for some, but negative and isolating for others (e.g. older or poorer people). Progress is often transient, as faster electronics and computers dramatically shorten retention time of data, knowledge, and information loss (e.g. even photos may be unreadable within a generation). Progress and globalization are also destroying past languages and cultures. Advances cut across all areas of science and life, and the scope is vast from biology, medicine, agriculture, transport, electronics, computers, long-range communications, to a global economy. Reliance on technology causes unexpected technology-driven vulnerability to natural events (e.g. intense sunspot activity) that could annihilate advanced soci...

  4. A light in the dark?

    Science.gov (United States)

    Cartlidge, Edwin

    2008-08-01

    If you can bear to hear the truth you've spoken Twisted by knaves to make a trap for fools, ...you'll be a Man my son! It is rare that poetry enters modern scientific discourse, which is why the above quote from the poem "If..." by Rudyard Kipling catches the attention of the visitor to the homepage of DAMA, a group of dark-matter hunters in Italy. Although the physicists in the group do not spell out explicitly what the poem refers to, its meaning seems fairly clear. The quote is an eloquent retort to their critics (the "knaves"), who for the last 10 years have been unconvinced of the researchers' claim to have made the first-ever direct observation of darkmatter particles ("the truth"). The poem illustrates the unusual intensity of the debate surrounding their claim.

  5. Neutron Dark-Field Imaging

    Science.gov (United States)

    Mullins, David

    2017-09-01

    Neutron imaging is typically used to image and reconstruct objects that are difficult to image using X-Ray imaging techniques. X-Ray absorption is primarily determined by the electron density of the material. This makes it difficult to image objects within materials that have high densities such as metal. However, the neutron scattering cross section primarily depends on the strong nuclear force, which varies somewhat randomly across the periodic table. In this project, an imaging technique known as dark field imaging using a far-field interferometer has been used to study a sample of granite. With this technique, interferometric phase images are generated. The dispersion of the microstructure of the sample dephases the beam, reducing the visibility. Collecting tomographic projections at different autocorrelation lengths (from 100 nanometers to 1.74 micrometers) essentially creates a 3D small angle scattering pattern, enabling mapping of how the microstructure is distributed throughout the sample.

  6. Dark matter in central galaxies

    Science.gov (United States)

    Salinas, R.; Richtler, T.; Romanowsky, A. J.; Schuberth, Y.; Gomez, M.; Hilker, M.

    The study of the dynamics of globular clusters systems (GCSs) is a powerful tool to test the dark matter (DM) content at galactic scales, especially in early type galaxies which present a lack of suitable DM probes (Romanowsky 2006). So far, this method has been only applied to a handful of nearby ellipticals, mainly due to the observational difficulties (Cote et al. 2001; Richtler et al. 2004; Schuberth et al. 2006; Woodley et al. 2007). In this talk I will present the first results of our VLT-VIMOS study of the dynamics of the GCS of NGC 3311, the nearest cD galaxy, which hosts an enormous GC population (McLaughlin et al. 1995). These results include the spectroscopic confirmation of the first ultra compact dwarf in Hydra I, from the candidate list of Wehner & Harris (2007).

  7. CP violating scalar Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Cordero-Cid, A.; Hernández-Sánchez, J. [Instituto de Física and Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 542, C.P. 72570 Puebla (Mexico); Keus, V. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Gustaf Hallstromin katu 2, Helsinki, FIN-00014 (Finland); School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); King, S.F. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Moretti, S. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom); Rojas, D. [Instituto de Física and Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 542, C.P. 72570 Puebla (Mexico); Sokołowska, D. [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland)

    2016-12-05

    We study an extension of the Standard Model (SM) in which two copies of the SM scalar SU(2) doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are inert, are added to the scalar sector. We allow for CP-violation in the inert sector, where the lightest inert state is protected from decaying to SM particles through the conservation of a Z{sub 2} symmetry. The lightest neutral particle from the inert sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.

  8. Protecting Dark Skies in Chile

    Science.gov (United States)

    Smith, R. Chris; Sanhueza, Pedro; Phillips, Mark

    2018-01-01

    Current projections indicate that Chile will host approximately 70% of the astronomical collecting area on Earth by 2030, augmenting the enormous area of ALMA with that of three next-generation optical telescopes: LSST, GMTO, and E-ELT. These cutting-edge facilities represent billions of dollars of investment in the astronomical facilities hosted in Chile. The Chilean government, Chilean astronomical community, and the international observatories in Chile have recognized that these investments are threatened by light pollution, and have formed a strong collaboration to work at managing the threats. We will provide an update on the work being done in Chile, ranging from training municipalities about new lighting regulations to exploring international recognition of the dark sky sites of Northern Chile.

  9. Phantom dark energy with varying-mass dark matter particles: Acceleration and cosmic coincidence problem

    International Nuclear Information System (INIS)

    Leon, Genly; Saridakis, Emmanuel N.

    2010-01-01

    We investigate several varying-mass dark matter particle models in the framework of phantom cosmology. We examine whether there exist late-time cosmological solutions, corresponding to an accelerating universe and possessing dark energy and dark matter densities of the same order. Imposing exponential or power-law potentials and exponential or power-law mass dependence, we conclude that the coincidence problem cannot be solved or even alleviated. Thus, if dark energy is attributed to the phantom paradigm, varying-mass dark matter models cannot fulfill the basic requirement that led to their construction.

  10. Flooded Dark Matter and S level rise

    Energy Technology Data Exchange (ETDEWEB)

    Randall, Lisa; Scholtz, Jakub [Department of Physics, Harvard University,Cambridge, MA 02138 (United States); Unwin, James [Department of Physics, University of Illinois at Chicago,Chicago, IL 60607 (United States)

    2016-03-03

    Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as “Maximum Baroqueness”. We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant

  11. Flooded Dark Matter and S level rise

    International Nuclear Information System (INIS)

    Randall, Lisa; Scholtz, Jakub; Unwin, James

    2016-01-01

    Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as “Maximum Baroqueness”. We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant

  12. SUSY dark matter: Beyond the standard paradigm

    International Nuclear Information System (INIS)

    Sandick, Pearl

    2016-01-01

    Within the framework of the Minimal Supersymmetric Standard Model (MSSM), we explore a decoupling of the parameters into separate sectors that determine consistency with collider data, the abundance of dark matter, and potential signatures at direct dark matter searches. We consider weak-scale bino-like neutralino dark matter, and find that annihilations via light slepton exchange present a viable mechanism for obtaining the appropriate dark matter abundance assuming a thermal history. Constraints and prospects for discovery of these models are discussed, including the possibility that direct dark matter searches may be sensitive to these models if light squarks exhibit left-right mixing. Differences between the scenarios presented here and the typical expectations for the MSSM are discussed.

  13. An introduction to particle dark matter

    CERN Document Server

    Profumo, Stefano

    2017-01-01

    What is the dark matter that fills the Universe and binds together galaxies? How was it produced? What are its interactions and particle properties?The paradigm of dark matter is one of the key developments at the interface of cosmology and elementary particle physics. It is also one of the foundations of the standard cosmological model. This book presents the state of the art in building and testing particle models for dark matter. Each chapter gives an analysis of questions, research directions, and methods within the field. More than 200 problems are included to challenge and stimulate the reader's knowledge and provide guidance in the practical implementation of the numerous 'tools of the trade' presented. Appendices summarize the basics of cosmology and particle physics needed for any quantitative understanding of particle models for dark matter.This interdisciplinary textbook is essential reading for anyone interested in the microscopic nature of dark matter as it manifests itself in particle physics ex...

  14. Planckian Interacting Massive Particles as Dark Matter

    DEFF Research Database (Denmark)

    Garny, Mathias; Sandora, McCullen; Sloth, Martin S.

    2016-01-01

    . In this case the WIMP miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian Interacting Massive Particle......, we show that the most natural mass larger than $0.01\\,\\textrm{M}_p$ is already ruled out by the absence of tensor modes in the CMB. This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the KK graviton mode...... as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark...

  15. Scalar dark matter with type II seesaw

    Directory of Open Access Journals (Sweden)

    Arnab Dasgupta

    2014-12-01

    Full Text Available We study the possibility of generating tiny neutrino mass through a combination of type I and type II seesaw mechanism within the framework of an abelian extension of standard model. The model also provides a naturally stable dark matter candidate in terms of the lightest neutral component of a scalar doublet. We compute the relic abundance of such a dark matter candidate and also point out how the strength of type II seesaw term can affect the relic abundance of dark matter. Such a model which connects neutrino mass and dark matter abundance has the potential of being verified or ruled out in the ongoing neutrino, dark matter, as well as accelerator experiments.

  16. 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.

  17. Cosmological simulations of multicomponent cold dark matter.

    Science.gov (United States)

    Medvedev, Mikhail V

    2014-08-15

    The nature of dark matter is unknown. A number of dark matter candidates are quantum flavor-mixed particles but this property has never been accounted for in cosmology. Here we explore this possibility from the first principles via extensive N-body cosmological simulations and demonstrate that the two-component dark matter model agrees with observational data at all scales. Substantial reduction of substructure and flattening of density profiles in the centers of dark matter halos found in simulations can simultaneously resolve several outstanding puzzles of modern cosmology. The model shares the "why now?" fine-tuning caveat pertinent to all self-interacting models. Predictions for direct and indirect detection dark matter experiments are made.

  18. Di-photon excess illuminates dark matter

    International Nuclear Information System (INIS)

    Backović, Mihailo; Mariotti, Alberto; Redigolo, Diego

    2016-01-01

    We propose a simplified model of dark matter with a scalar mediator to accommodate the di-photon excess recently observed by the ATLAS and CMS collaborations. Decays of the resonance into dark matter can easily account for a relatively large width of the scalar resonance, while the magnitude of the total width combined with the constraint on dark matter relic density leads to sharp predictions on the parameters of the Dark Sector. Under the assumption of a rather large width, the model predicts a signal consistent with ∼300 GeV dark matter particle and ∼750 GeV scalar mediator in channels with large missing energy. This prediction is not yet severely bounded by LHC Run I searches and will be accessible at the LHC Run II in the jet plus missing energy channel with more luminosity. Our analysis also considers astro-physical constraints, pointing out that future direct detection experiments will be sensitive to this scenario.

  19. Gravity-mediated (or Composite) Dark Matter

    CERN Document Server

    Lee, Hyun Min; Sanz, Veronica

    2014-01-01

    Dark matter could have an electroweak origin, yet communicate with the visible sector exclusively through gravitational interactions. In a set-up addressing the hierarchy problem, we propose a new dark matter scenario where gravitational mediators, arising from the compactification of extra-dimensions, are responsible for dark matter interactions and its relic abundance in the Universe. We write an explicit example of this mechanism in warped extra-dimensions and work out its constraints. We also develop a dual picture of the model, based on a four-dimensional scenario with partial compositeness. We show that Gravity-mediated Dark Matter is equivalent to a mechanism of generating viable dark matter scenarios in a strongly-coupled, near-conformal theory, such as in composite Higgs models.

  20. Off-diagonal dark-matter phenomenology: Exploring enhanced complementarity relations in nonminimal dark sectors

    Science.gov (United States)

    Dienes, Keith R.; Kumar, Jason; Thomas, Brooks; Yaylali, David

    2017-12-01

    In most multicomponent dark-matter scenarios, two classes of processes generically contribute to event rates at experiments capable of probing the nature of the dark sector. The first class consists of "diagonal" processes involving only a single species of dark-matter particle—processes analogous to those which arise in single-component dark-matter scenarios. By contrast, the second class consists of "off-diagonal" processes involving dark-matter particles of different species. Such processes include inelastic scattering at direct-detection experiments, asymmetric production at colliders, dark-matter co-annihilation, and certain kinds of dark-matter decay. In typical multicomponent scenarios, the contributions from diagonal processes dominate over those from off-diagonal processes. Unfortunately, this tends to mask those features which are most sensitive to the multicomponent nature of the dark sector. In this paper, by contrast, we point out that there exist natural, multicomponent dark-sector scenarios in which the off-diagonal contributions actually dominate over the diagonal. This then gives rise to a new, enhanced picture of dark-matter complementarity. In this paper, we introduce a scenario in which this situation arises and examine the enhanced picture of dark-matter complementarity which emerges.

  1. 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...

  2. Faces in the dark: Interactive effects of darkness and anxiety on the memory for threatening faces.

    Directory of Open Access Journals (Sweden)

    Satoshi F Nakashima

    2014-10-01

    Full Text Available In the current research, we extend past work on the effects of ambient darkness and threat to the domain of memory for expressive faces. In one study, we examined the effects of ambient darkness and individual differences in state anxiety on memory of unfamiliar expressive faces. Here, participants were seated in either a dark or light room and encoded a set of unfamiliar faces with angry, happy, and neutral facial expressions. A subsequent recognition task revealed an interactive effect of ambient darkness, anxiety, and target expression. Highly anxious participants in ambient darkness had worse memory for angry faces than did low-anxiety participants. On the other hand, the recognition performance for happy faces was affected neither by the darkness nor state anxiety. The results suggest not only that ambient darkness has its strongest effect on anxious perceivers, but also that person x situation effects should be considered in face recognition research.

  3. Possible dark energy imprints in the gravitational wave spectrum of mixed neutron-dark-energy stars

    Energy Technology Data Exchange (ETDEWEB)

    Yazadjiev, Stoytcho S. [Department of Theoretical Physics, Faculty of Physics, St. Kliment Ohridski University of Sofia, James Bourchier Blvd. 5, 1164 Sofia (Bulgaria); Doneva, Daniela D., E-mail: yazad@phys.uni-sofia.bg, E-mail: daniela.doneva@uni-tuebingen.de [Theoretical Astrophysics, IAAT, Eberhard-Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen (Germany)

    2012-03-01

    In the present paper we study the oscillation spectrum of neutron stars containing both ordinary matter and dark energy in different proportions. Within the model we consider, the equilibrium configurations are numerically constructed and the results show that the properties of the mixed neuron-dark-energy star can differ significantly when the amount of dark energy in the stars is varied. The oscillations of the mixed neuron-dark-energy stars are studied in the Cowling approximation. As a result we find that the frequencies of the fundamental mode and the higher overtones are strongly affected by the dark energy content. This can be used in the future to detect the presence of dark energy in the neutron stars and to constrain the dark-energy models.

  4. What FDA Learned About Dark Chocolate and Milk Allergies

    Science.gov (United States)

    ... For Consumers Home For Consumers Consumer Updates Dark Chocolate and Milk Allergies Share Tweet Linkedin Pin it ... of the firm. Milk Detected in Individual Dark Chocolate Products Label/Package Statement Total number of dark ...

  5. 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

    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...

  6. Ratcheting Up The Search for Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    McDermott, Samuel Dylan [Univ. of Michigan, Ann Arbor, MI (United States)

    2014-01-01

    The last several years have included remarkable advances in two of the primary areas of fundamental particle physics: the search for dark matter and the discovery of the Higgs boson. This dissertation will highlight some contributions made on the forefront of these exciting fields. Although the circumstantial evidence supporting the dark matter hypothesis is now almost undeniably significant, indisputable direct proof is still lacking. As the direct searches for dark matter continue, we can maximize our prospects of discovery by using theoretical techniques complementary to the observational searches to rule out additional, otherwise accessible parameter space. In this dissertation, I report bounds on a wide range of dark matter theories. The models considered here cover the spectrum from the canonical case of self-conjugate dark matter with weak-scale interactions, to electrically charged dark matter, to non-annihilating, non-fermionic dark matter. These bounds are obtained from considerations of astrophysical and cosmological data, including, respectively: diffuse gamma ray photon observations; structure formation considerations, along with an explication of the novel local dark matter structure due to galactic astrophysics; and the existence of old pulsars in dark-matter-rich environments. I also consider the prospects for a model of neutrino dark matter which has been motivated by a wide set of seemingly contradictory experimental results. In addition, I include a study that provides the tools to begin solving the speculative ``inverse'' problem of extracting dark matter properties solely from hypothetical nuclear energy spectra, which we may face if dark matter is discovered with multiple direct detection experiments. In contrast to the null searches for dark matter, we have the example of the recent discovery of the Higgs boson. The Higgs boson is the first fundamental scalar particle ever observed, and precision measurements of the production and

  7. Cold dark matter. 1: The formation of dark halos

    Science.gov (United States)

    Gelb, James M.; Bertschinger, Edmund

    1994-01-01

    We use numerical simulations of critically closed cold dark matter (CDM) models to study the effects of numerical resolution on observable quantities. We study simulations with up to 256(exp 3) particles using the particle-mesh (PM) method and with up to 144(exp 3) particles using the adaptive particle-particle-mesh (P3M) method. Comparisons of galaxy halo distributions are made among the various simulations. We also compare distributions with observations, and we explore methods for identifying halos, including a new algorithm that finds all particles within closed contours of the smoothed density field surrounding a peak. The simulated halos show more substructure than predicted by the Press-Schechter theory. We are able to rule out all omega = 1 CDM models for linear amplitude sigma(sub 8) greater than or approximately = 0.5 because the simulations produce too many massive halos compared with the observations. The simulations also produce too many low-mass halos. The distribution of halos characterized by their circular velocities for the P3M simulations is in reasonable agreement with the observations for 150 km/s less than or = V(sub circ) less than or = 350 km/s.

  8. Brief History of Ultra-light Scalar Dark Matter Models

    Directory of Open Access Journals (Sweden)

    Lee Jae-Weon

    2018-01-01

    dark matter, BEC dark matter, wave dark matter, or ultra-light axion. In this model ultra-light scalar dark matter particles with mass m = O(10-22eV condense in a single Bose-Einstein condensate state and behave collectively like a classical wave. Galactic dark matter halos can be described as a self-gravitating coherent scalar field configuration called boson stars. At the scale larger than galaxies the dark matter acts like cold dark matter, while below the scale quantum pressure from the uncertainty principle suppresses the smaller structure formation so that it can resolve the small scale crisis of the conventional cold dark matter model.

  9. Condensation of galactic cold dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Visinelli, Luca [Nordita, KTH Royal Institute of Technology and Stockholm University,SE-106 91 Stockholm (Sweden)

    2016-07-07

    We consider the steady-state regime describing the density profile of a dark matter halo, if dark matter is treated as a Bose-Einstein condensate. We first solve the fluid equation for “canonical” cold dark matter, obtaining a class of density profiles which includes the Navarro-Frenk-White profile, and which diverge at the halo core. We then solve numerically the equation obtained when an additional “quantum pressure” term is included in the computation of the density profile. The solution to this latter case is finite at the halo core, possibly avoiding the “cuspy halo problem” present in some cold dark matter theories. Within the model proposed, we predict the mass of the cold dark matter particle to be of the order of M{sub χ}c{sup 2}≈10{sup −24} eV, which is of the same order of magnitude as that predicted in ultra-light scalar cold dark matter models. Finally, we derive the differential equation describing perturbations in the density and the pressure of the dark matter fluid.

  10. 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.

  11. 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.

  12. Condensation of galactic cold dark matter

    International Nuclear Information System (INIS)

    Visinelli, Luca

    2016-01-01

    We consider the steady-state regime describing the density profile of a dark matter halo, if dark matter is treated as a Bose-Einstein condensate. We first solve the fluid equation for “canonical” cold dark matter, obtaining a class of density profiles which includes the Navarro-Frenk-White profile, and which diverge at the halo core. We then solve numerically the equation obtained when an additional “quantum pressure” term is included in the computation of the density profile. The solution to this latter case is finite at the halo core, possibly avoiding the “cuspy halo problem” present in some cold dark matter theories. Within the model proposed, we predict the mass of the cold dark matter particle to be of the order of M χ c 2 ≈10 −24 eV, which is of the same order of magnitude as that predicted in ultra-light scalar cold dark matter models. Finally, we derive the differential equation describing perturbations in the density and the pressure of the dark matter fluid.

  13. 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.)

  14. Dark Skies are a Universal Resource: IYA Programs on Dark Skies Awareness

    Science.gov (United States)

    Walker, Constance E.; Bueter, C.; Pompea, S. M.; Berglund, K.; Mann, T.; Gay, P.; Crelin, B.; Collins, D.; Sparks, R.

    2008-05-01

    The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also health, ecology, safety, economics and energy conservation. Because of its relevance, "Dark Skies” is a theme of the US Node for the International Year of Astronomy (IYA). Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. To reach this goal, the ASP session will immerse participants in hands-on, minds-on activities, events and resources on dark skies awareness. These include a planetarium show on DVD, podcasting, social networking, a digital photography contest, The Great Switch Out, Earth Hour, National Dark Skies Week, a traveling exhibit, a 6-minute video tutorial, Dark Skies Teaching Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights, and unaided-eye and digital-meter star counting programs like GLOBE at Night. The ASP "Dark Skies” session is offered to provide IYA dark skies-related programs to a variety of attendees. Participants include professional or amateur astronomers, education and public outreach professionals, science center/museum/planetarium staff and educators who want to lead activities involving dark skies awareness in conjunction with IYA. During the session, each participant will be given a package of educational materials on the various dark skies programs. We will provide the "know-how” and the means for session attendees to become community leaders in promoting these dark skies programs as public events at their home institutions during IYA. Participants will be able to jump-start their education programs through the use of well-developed instructional materials and kits sent later if they commit to leading IYA dark skies activities. For more information about the IYA Dark Skies theme, visit http://astronomy2009.us/darkskies/.

  15. Dark Matter Searches with the ATLAS Detector

    CERN Document Server

    Elliot, Alison; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature.  The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  16. Dark Matter searches with the ATLAS Detector

    CERN Document Server

    Cortes-Gonzalez, Arely; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  17. Dark matter searches with the ATLAS detector

    CERN Document Server

    Whalen, Kathleen; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as its signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches using the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  18. Dark Matter searches with the ATLAS Detector

    CERN Document Server

    Ippolito, Valerio; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic Dark Matter component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model particles it may be produced at the Large Hadron Collider (LHC), escaping detection and leaving large missing transverse momentum as its signature. New results from the Dark Matter search programme of the ATLAS experiment are presented, based on LHC proton-proton collision data collected at a center-of-mass energy of 13 TeV.

  19. String theory and the dark glueball problem

    Science.gov (United States)

    Halverson, James; Nelson, Brent D.; Ruehle, Fabian

    2017-02-01

    We study cosmological constraints on dark pure Yang-Mills sectors. Dark glueballs are overproduced for large regions of ultraviolet parameter space. The problem may be alleviated in two ways: via a large preferential reheating into the visible sector, motivating certain inflation or modulus decay models, or via decays into axions or moduli, which are strongly constrained by nucleosynthesis and Δ Neff bounds. String models frequently have multiple hidden Yang-Mills sectors, which are subject to even stronger constraints due to the existence of multiple dark glueballs.

  20. The Dark Side of Neutron Stars

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos

    2013-01-01

    We review severe constraints on asymmetric bosonic dark matter based on observations of old neutron stars. Under certain conditions, dark matter particles in the form of asymmetric bosonic WIMPs can be eectively trapped onto nearby neutron stars, where they can rapidly thermalize and concentrate...... in the core of the star. If some conditions are met, the WIMP population can collapse gravitationally and form a black hole that can eventually destroy the star. Based on the existence of old nearby neutron stars, we can exclude certain classes of dark matter candidates....

  1. The adiabatic instability on cosmology's dark side

    International Nuclear Information System (INIS)

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

    2008-01-01

    We consider theories with a nontrivial coupling between the matter and dark energy sectors. We describe a small scale instability that can occur in such models when the coupling is strong compared to gravity, generalizing and correcting earlier treatments. The instability is characterized by a negative sound speed squared of an effective coupled dark matter/dark energy fluid. Our results are general, and applicable to a wide class of coupled models and provide a powerful, redshift-dependent tool, complementary to other constraints, with which to rule many of them out. A detailed analysis and applications to a range of models are presented in a longer companion paper

  2. Interstellar extinction in the Taurus dark clouds

    International Nuclear Information System (INIS)

    Meistas, E.; Straizys, V.

    1981-01-01

    The results of photoelectric photometry of 89 stars in the Vilnius seven-color system in the area of the Taurus dark clouds with corrdinates (1950) 4sup(h)16sup(m)-4sup(h)33sup(m), +16 0 -+20 0 are presented. Photometric spectral types, absolute magnitude, color excesses, interstellar extinctions and distances of the stars are determined. The distance of the dark nebula is found to be 140 pc and is in a good agreement with the distance determined for the dark nebula Khavtassi 286, 278. The average extinction Asub(v) in the investigated area is of the order of 1.4. (author)

  3. The cosmic cocktail three parts dark matter

    CERN Document Server

    Freese, Katherine

    2014-01-01

    The ordinary atoms that make up the known universe-from our bodies and the air we breathe to the planets and stars-constitute only 5 percent of all matter and energy in the cosmos. The rest is known as dark matter and dark energy, because their precise identities are unknown. The Cosmic Cocktail is the inside story of the epic quest to solve one of the most compelling enigmas of modern science - what is the universe made of? - told by one of today's foremost pioneers in the study of dark matter. Blending cutting-edge science with her own behind-the-scenes insights as a leading researcher in the

  4. 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.

  5. On baryogenesis from dark matter annihilation

    International Nuclear Information System (INIS)

    Bernal, Nicolás; Colucci, Stefano; Ubaldi, Lorenzo; Josse-Michaux, François-Xavier; Racker, J.

    2013-01-01

    We study in detail the conditions to generate the baryon asymmetry of the universe from the annihilation of dark matter. This scenario requires a low energy mechanism for thermal baryogenesis, hence we first discuss some of these mechanisms together with the specific constraints due to the connection with the dark matter sector. Then we show that, contrary to what stated in previous studies, it is possible to generate the cosmological asymmetry without adding a light sterile dark sector, both in models with violation and with conservation of B−L. In addition, one of the models we propose yields some connection to neutrino masses

  6. Constraints on hadronically decaying dark matter

    International Nuclear Information System (INIS)

    Garny, Mathias; Ibarra, Alejandro; Tran, David; Minnesota Univ., Minneapolis, MN

    2012-05-01

    We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons.We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.

  7. Dark Matter Searches with the ATLAS detector

    Directory of Open Access Journals (Sweden)

    Elliot Alison

    2017-01-01

    Full Text Available The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as its signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  8. Dark matter searches with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00379232; The ATLAS collaboration

    2017-01-01

    The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as its signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  9. 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

  10. Dark Matter from new Technicolor Theories

    DEFF Research Database (Denmark)

    Bjarke Gudnason, Sven; Kouvaris, Christoforos; Sannino, Francesco

    2006-01-01

    We investigate dark matter candidates emerging in recently proposed technicolor theories. We determine the relic density of the lightest, neutral, stable technibaryon having imposed weak thermal equilibrium conditions and overall electric neutrality of the Universe. In addition we consider...... sphaleron processes that violate baryon, lepton and technibaryon number. Our analysis is performed in the case of a first order electroweak phase transition as well as a second order one. We argue that, in both cases, the new technibaryon contributes to the dark matter in the Universe. Finally we examine...... the problem of the constraints on these types of dark matter components from earth based experiments....

  11. 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...

  12. Evaluation of a dark-room

    International Nuclear Information System (INIS)

    Passos, J.C.

    1987-01-01

    The adequate operation conditions of a dark-room are essential to guarantee the image quality, the least exposure of the patient and the staff, contributing also to reduce the expenses with specific equipments and processing solutions. Therefore, to install a dark-room, it is necessary a previous study about its physical dimensions, the location of equipments, accessories, light safeguards and visual warning, besides adequate darkening and correct filme processing. We propose three basic tests to check the adequacy and the integrity of a dark-room: light safeguards test, hygiene test, developing time and temperature test. (Author) [pt

  13. Searches for Dark Matter at the LHC

    CERN Document Server

    Sciolla, Gabriella; The ATLAS collaboration

    2016-01-01

    Dark Matter can be produced in large amounts in pp collisions at the Large Hadron Collider (LHC) assuming it interacts non-gravitationally with Standard Model particles. While Dark Matter escapes direct detection at the LHC, it leaves a distinct signature of significant missing transverse momentum. In this talk, recent results from the ATLAS and CMS detectors will be presented, based on events with large missing transverse momentum accompanied by a variety of other objects such as jets, photons, heavy-flavor quarks, weak gauge bosons, or Higgs bosons. These measurements are complementary to those obtained in direct and indirect Dark Matter detection experiments.

  14. Searches for Dark Matter in ATLAS

    CERN Document Server

    Alpigiani, Cristiano; The ATLAS collaboration

    2017-01-01

    Although the existence of Dark Matter (DM) is well established by many astronomical measurements, its nature still remains one of the unsolved puzzles of particles physics. The unprecedented energy reached by the Large Hadron Collider (LHC) at CERN has allowed exploration of previously unaccessible kinematic regimes in the search for new phenomena. An overview of most recent searches for dark matter with the ATLAS detector at LHC is presented and the interpretation of the results in terms of effective field theory and simplified models is discussed. The exclusion limits set by the ATLAS searches are compared to the constraints from direct dark matter detection experiments.

  15. Can Neutron stars constrain Dark Matter?

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos; Tinyakov, Peter

    2010-01-01

    We argue that observations of old neutron stars can impose constraints on dark matter candidates even with very small elastic or inelastic cross section, and self-annihilation cross section. We find that old neutron stars close to the galactic center or in globular clusters can maintain a surface...... temperature that could in principle be detected. Due to their compactness, neutron stars can acrete WIMPs efficiently even if the WIMP-to-nucleon cross section obeys the current limits from direct dark matter searches, and therefore they could constrain a wide range of dark matter candidates....

  16. Does dark chocolate have a role in the prevention and management of hypertension?: commentary on the evidence.

    Science.gov (United States)

    Egan, Brent M; Laken, Marilyn A; Donovan, Jennifer L; Woolson, Robert F

    2010-06-01

    The notion that eating chocolate would prevent or treat hypertension is appealing to many who produce and enjoy chocolate. Several studies have documented beneficial effects of dark chocolate on insulin action and endothelial function. However, the published studies on chocolate and blood pressure include a relatively small number of subjects, and results are conflicting. In addition, because of secrecy surrounding the production of chocolate and the unique sociocultural context of this popular food, research on efficacy and effectiveness is complex. This commentary summarizes 13 peer-reviewed studies on dark chocolate and blood pressure and raises questions relevant to its future as an evidence-based lifestyle intervention.

  17. Twin Higgs WIMP dark matter

    Science.gov (United States)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-01

    Dark matter (DM) without a matter asymmetry is studied in the context of twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) Z2 symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realization of the TH mechanism, the fraternal twin Higgs, with only a single generation of twin quarks and leptons, and the S U (3 )'×S U (2 )' gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the τ' lepton with a mass mτ'>mHiggs/2 , although spin-1 W'± DM and multicomponent DM are also possible (twin baryons are strongly disfavored by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to the number of relativistic degrees of freedom, Δ Neff . Direct detection signals are below current bounds but accessible in near-future experiments. Indirect detection phenomenology is rich and requires detailed studies of twin hadronization and fragmentation to twin glueballs and quarkonia and their subsequent decay to SM, and possible light twin sector states.

  18. Naturalness of MSSM dark matter

    International Nuclear Information System (INIS)

    Cabrera, María Eugenia; Casas, J. Alberto; Delgado, Antonio; Robles, Sandra; Austri, Roberto Ruiz de

    2016-01-01

    There exists a vast literature examining the electroweak (EW) fine-tuning problem in supersymmetric scenarios, but little concerned with the dark matter (DM) one, which should be combined with the former. In this paper, we study this problem in an, as much as possible, exhaustive and rigorous way. We have considered the MSSM framework, assuming that the LSP is the lightest neutralino, χ 1 0 , and exploring the various possibilities for the mass and composition of χ 1 0 , as well as different mechanisms for annihilation of the DM particles in the early Universe (well-tempered neutralinos, funnels and co-annihilation scenarios). We also present a discussion about the statistical meaning of the fine-tuning and how it should be computed for the DM abundance, and combined with the EW fine-tuning. The results are very robust and model-independent and favour some scenarios (like the h-funnel when M χ 1 0 is not too close to m h /2) with respect to others (such as the pure wino case). These features should be taken into account when one explores “natural SUSY” scenarios and their possible signatures at the LHC and in DM detection experiments.

  19. Concordance cosmology without dark energy

    Science.gov (United States)

    Rácz, Gábor; Dobos, László; Beck, Róbert; Szapudi, István; Csabai, István

    2017-07-01

    According to the separate universe conjecture, spherically symmetric sub-regions in an isotropic universe behave like mini-universes with their own cosmological parameters. This is an excellent approximation in both Newtonian and general relativistic theories. We estimate local expansion rates for a large number of such regions, and use a scale parameter calculated from the volume-averaged increments of local scale parameters at each time step in an otherwise standard cosmological N-body simulation. The particle mass, corresponding to a coarse graining scale, is an adjustable parameter. This mean field approximation neglects tidal forces and boundary effects, but it is the first step towards a non-perturbative statistical estimation of the effect of non-linear evolution of structure on the expansion rate. Using our algorithm, a simulation with an initial Ωm = 1 Einstein-de Sitter setting closely tracks the expansion and structure growth history of the Λ cold dark matter (ΛCDM) cosmology. Due to small but characteristic differences, our model can be distinguished from the ΛCDM model by future precision observations. Moreover, our model can resolve the emerging tension between local Hubble constant measurements and the Planck best-fitting cosmology. Further improvements to the simulation are necessary to investigate light propagation and confirm full consistency with cosmic microwave background observations.

  20. Dark matter, hot and cold

    International Nuclear Information System (INIS)

    Shafi, Qaisar

    1993-01-01

    Cosmologists responded enthusiastically to the announcement at the Washington meeting of the American Physical Society in April 1992 that the Cosmic Background Explorer (COBE) had succeeded in detecting primordial anisotropies in the cosmic microwave background radiation (CMB - June 1992, page 1). The COBE satellite was launched in November 1989 into an orbit approximately 900 km above the Earth, carrying instruments to make precise measurements of the spectrum and anisotropy of the CMB. Data from the Far-lnfra Red Absolute Spectrophotometer (FIRAS) beautifully shows the CMB spectrum to be that of a black body at a temperature of 2.73±0.06K. An even more important result, at least from the viewpoint of theories of large scale structure formation (LSS), comes from the Differential Microwave Radiometer (DMR) which provided the first evidence for CMB anisotropy. Some anisotropy on the angular slice probed by COBE is expected in any reasonable model of LSS. COBE's measurement of the quadrupole anisotropy at six parts per million provides an important clue for developing a 'standard model' of LSS. The COBE numbers are in remarkably good agreement with the predictions of a particularly simple class of LSS models proposed almost a decade ago, with far reaching implications for dark matter searches