China's Shineray Racing Team Hits International Circuit
无
2006-01-01
@@ China Shineray International Motocross Racing Team is Chongqing Shineray Group's international racing team, established in March 2004. in less than two years, this team has developed into the representative of numerous Chinese enterprises.
The Peccei-Quinn symmetry is a possible solution to the strong C.P. violation problem resulting from instantons contributions. It is the objective of this dissertation to study models which incorporate the Paccei-Ouinn symmetry as well as its consequences, for instance, the exiatence of a Goldstone pseudoboson named axion and the appearence of topologically satble structures generated at the spontaneous breakdown of the Peccei-Quinn symmetry. We also study the interchanged between axion models and Cosmology, particularly the influence of axions on the process of galsxy formation. (author)
Axion physics is briefly reviewed, including the constraints on the axion decay constant from laboratory experiments, from stellar evolution and from the cosmological axion energy density. Experiments to detect axions emitted by the sun or axions floating about in the halo of our galaxy are discussed. 19 references
The Axion Dark Matter Experiment: Big Science with a (relatively) Small Team
Carosi, Gianpaolo
2016-03-01
The idea of the solitary physicist tinkering alone in a lab was my image of how science was done growing up (mostly influenced by popular culture). Of course this is not generally how experimental physics is done now days with examples of experiments at the LHC now involving thousands of scientists. In this talk I will describe my experience in a relatively modest project, the Axion Dark Matter eXperiment (ADMX), which involves only a few dozen scientists at various universities and national labs. I will outline ADMX's humble beginnings at Lawrence Livermore National Laboratory (LLNL), where it began in the mid-1990s, and describe how the collaboration has evolved and grown throughout the years, as we pursue our elusive quarry: the dark-matter axion. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE- AC52-07NA27344, DE-AC03-76SF00098, and the Livermore LDRD program.
Hayashi, Y. [Aoyama Gakuin University, Tokyo (Japan)
1994-09-20
This paper introduces how the Aoyama Gakuin University team competed in the World Solar Car Rally race held at Ogata Village in Akita Prefecture, Japan, in the summer of 1994. The race was formed with solar cars mounting a solar panel with the maximum area of 8 m{sup 2} and batteries with a total output of 3 kWh to compete how many rounds the cars can run around a course of 31 km during three days (25 hours in total). The solar car used by the University team had consumed power of about 600 W at a speed of 40 km/h, with the solar panel generating power of 800 Wp. The first day morning was sunny making possible to set the average speed to 45 km/h (power generation of 500 W or more), but the weather worsened in the afternoon compelling the car to change the speed to 30 km/h (power generation of 200 W). The power generated on the second day, which was cloudy all day, stayed at 250 W at the maximum, hence the speed was kept at 30 km/h to suppress the power consumption. On the sunny third day, the team drove the car worrying about the remaining battery capacity, and succeeded the drive of 23 rounds in total, winning the second prize among 30 cars participated in the junior class race.
Montero, Miguel; Valenzuela, Irene
2015-01-01
We discuss quantum gravitational effects in Einstein theory coupled to periodic axion scalars to analyze the viability of several proposals to achieve superplanckian axion periods (aka decay constants) and their possible application to large field inflation models. The effects we study correspond to the nucleation of euclidean gravitational instantons charged under the axion, and our results are essentially compatible with (but independent of) the Weak Gravity Conjecture, as follows: Single axion theories with superplanckian periods contain gravitational instantons inducing sizable higher harmonics in the axion potential, which spoil superplanckian inflaton field range. A similar result holds for multi-axion models with lattice alignment (like the Kim-Nilles-Peloso model). Finally, theories with $N$ axions can still achieve a moderately superplanckian periodicity (by a $\\sqrt{N}$ factor) with no higher harmonics in the axion potential. The Weak Gravity Conjecture fails to hold in this case due to the absence ...
Marsh, David J. E.
2016-07-01
Axions comprise a broad class of particles that can play a major role in explaining the unknown aspects of cosmology. They are also well-motivated within high energy physics, appearing in theories related to CP-violation in the standard model, supersymmetric theories, and theories with extra-dimensions, including string theory, and so axion cosmology offers us a unique view onto these theories. I review the motivation and models for axions in particle physics and string theory. I then present a comprehensive and pedagogical view on the cosmology and astrophysics of axion-like particles, starting from inflation and progressing via BBN, the CMB, reionization and structure formation, up to the present-day Universe. Topics covered include: axion dark matter (DM); direct and indirect detection of axions, reviewing existing and future experiments; axions as dark radiation; axions and the cosmological constant problem; decays of heavy axions; axions and stellar astrophysics; black hole superradiance; axions and astrophysical magnetic fields; axion inflation, and axion DM as an indirect probe of inflation. A major focus is on the population of ultralight axions created via vacuum realignment, and its role as a DM candidate with distinctive phenomenology. Cosmological observations place robust constraints on the axion mass and relic density in this scenario, and I review where such constraints come from. I next cover aspects of galaxy formation with axion DM, and ways this can be used to further search for evidence of axions. An absolute lower bound on DM particle mass is established. It is ma > 10-24eV from linear observables, extending to ma ≳ 10-22eV from non-linear observables, and has the potential to reach ma ≳ 10-18eV in the future. These bounds are weaker if the axion is not all of the DM, giving rise to limits on the relic density at low mass. This leads to the exciting possibility that the effects of axion DM on structure formation could one day be detected
Ototoxic occupational exposures for a stock car racing team: I. Noise surveys.
Van Campen, Luann E; Morata, Thais; Kardous, Chucri A; Gwin, Kristin; Wallingford, Kenneth M; Dallaire, Jacques; Alvarez, Frank J
2005-08-01
The National Institute for Occupational Safety and Health (NIOSH) surveyed noise exposure for a professional stock car team at their race shop and during two races at one racetrack. At the team's shop, area sound pressure levels (SPLs) were measured for various work tasks. Equivalent levels (Leqs) ranged from 58 to 104 decibels, A-weighted (dBA). Personal noise dosimetry was conducted for at least one employee for each job description in race car assembly (n = 9). The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 90 dBA for an 8-hour, 5-dB exchange rate time-weighted average (TWA) was never exceeded, but in two instances values exceeded OSHA's action level of 85 dBA for hearing conservation implementation. The NIOSH recommended exposure limit (REL) of 85 dBA for a 3-dB exchange rate Leq was exceeded for five of the measured jobs. During the races, SPLs averaged above 100 dBA in the pit area where cars undergo adjustments/refueling, both before and during the race. Peak levels reached 140 dB SPL. NIOSH REL was exceeded for every personal noise dosimetry measurement. Recommendations for hearing protection and communication are presented. PMID:16080260
Marsh, David J E
2015-01-01
Axions comprise a broad class of particles that can play a major role in explaining the unknown aspects of cosmology. They are also extraordinarily well-motivated within high energy physics, and so axion cosmology offers us a unique view onto these theories. I present a comprehensive and pedagogical view on the cosmology and astrophysics of axion-like particles, starting from inflation and progressing via the CMB and structure formation up to the present-day Universe. I briefly review the motivation and models for axions in particle physics and string theory. The primary focus is on the population of ultralight axions created via vacuum realignment, and its role as a dark matter (DM) candidate with distinctive phenomenology. Cosmological observations place robust constraints on the axion mass and relic density in this scenario, and I review where such constraints come from. I next cover aspects of galaxy formation with axion DM, and ways this can be used to further search for evidence of axions. An absolute l...
Dvali, Gia
2016-01-01
We attempt to identify a phenomenologically viable solution to the strong $CP$ problem in which the axion is composed entirely out of Standard Model fermion species. The axion consists predominantly of the $\\eta'$ meson with a minuscule admixture of a pseudoscalar bilinear composite of neutrinos, $\\eta_{\
Ringwald, A.
2012-01-01
In this master's thesis we study the cosmological consequences of the new scalar field, the axion, that appears in the U(1)_PQ extension of the standard model of particle physics. We start by presenting some essential fragments of the standard model of Big Bang cosmology, that are needed when we describe the evolution of the axion field in the early Universe. We also review the basics of phase transitions in the early Universe, and go through the creation and evolution of the topological defe...
The possibility of axion production in the Earth's interior due to natural radioactive decay is considered. Axions, or axion-like particles, could be created in nuclear disintegrations and deexitations of natural radionuclides present in the Earth's crust and mantle, as well as due to photon to axion conversion of the emitted gamma rays via the Primakoff effect. The estimated geo-axion production rates and fluxes on the Earth's surface are given along with the axion coupling to ordinary matter in the frame of the simple axion models as well as for axion-like particles with stronger couplings
Aurilia, A. (Dept. of Physics, California State Polytechnic Univ., Pomona, CA (United States)); Spallucci, E. (Dipt. di Fisica Teorica, Univ. Trieste (Italy) INFN, Sezione Trieste (Italy))
1992-05-21
A metal ring removed from a soap-water solution encloses a film of soap which can be mathematically described as a minimal surface having the ring as its only boundary. This is known to everybody. In this letter we suggest a relativistic extension of the above fluidodynamic system where the soap film is replaced by a Kalb-Ramand gauge potential B{sub {mu}{nu}}(x) and the ring by a closed string. The interaction between the B{sub {mu}{nu}} field and the string current excites a new configuration of the system consisting of a relativistic membrane bounded by the string. We call such a classical solution of the equation of motion an axionic membrane. As a dynamical system, the axionic membrane admits a Hamilton-Jacobi formulation which is an extension of the HJ theory of electromagnetic strings. (orig.).
Axions at the International Axion Observatory
Redondo, Javier
2016-01-01
QCD axions with meV mass can be behind some stellar cooling anomalies and form all or part of the cold dark matter of the universe. We discuss on a proposed experiment to discover the solar flux of meV mass axions: the International AXion Observatory: IAXO.
Chou, Aaron S.; /Fermilab
2009-10-01
Experimental searches for axions or axion-like particles rely on semiclassical phenomena resulting from the postulated coupling of the axion to two photons. Sensitive probes of the extremely small coupling constant can be made by exploiting familiar, coherent electromagnetic laboratory techniques, including resonant enhancement of transitions using microwave and optical cavities, Bragg scattering, and coherent photon-axion oscillations. The axion beam may either be astrophysical in origin as in the case of dark matter axion searches and solar axion searches, or created in the laboratory from laser interactions with magnetic fields. This note is meant to be a sampling of recent experimental results.
Design, analysis and simulation of the suspension system in the FS team UiS race car
Brevik, Vegard
2013-01-01
This master thesis concerns the design and analysis of the suspension for the Formula Student Team UiS racing car for the Formula Student 2013 student competition. To analyze how parameters such as track width, wheelbase, weight distribution, CoG height and total weight affected the overall performance a virtual racetrack was constructed. Calculations were then done to find the cars lap time as the various parameters were altered. Results showed that reduced weight and CoG height and in...
CERN. Geneva
2005-01-01
Outline of the lecture: Constraints from laboratory searches and astrophysics, axion cosmology, the cavity detector of dark matter axions, solar axion searches, laser experiments, a telescope search, macroscopic forces mediated by axions.
Braaten, Eric; Zhang, Hong
2015-01-01
If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure.If the axion mass energy is $mc^2= 10^{-4}$ eV, these dilute axion stars have a maximum mass of about $10^{-14} M_\\odot$. We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If $mc^2 = 10^{-4}$ eV, the first branch of these dense axion stars has mas...
Axions - Motivation, limits and searches
Raffelt, Georg G.
2006-01-01
The axion solution of the strong CP problem provides a number of possible windows to physics beyond the standard model, notably in the form of searches for solar axions and for galactic axion dark matter, but in a broader context also inspires searches for axion-like particles in pure laboratory experiments. We briefly review the motivation for axions, astrophysical limits, their possible cosmological role, and current searches for axions and axion-like particles.
The existence of axions, proposed as very light neutral pseudoscalar bosons, would solve the strong CP problem in the QCD. Axions also arise in supersymmetric and superstring theories and are candidates for dark matter in the universe. Cosmological and astrophysical arguments restrict the masses (ma) of invisible axions to rather narrow 10-5 eV → ma → 10-22 eV range, but with large uncertainties on either side. The KSVZ or hadronic axion is one version of invisible axions, which predicts small coupling of axions to electrons. Models of hadronic axions with E/N ≅ 2 allow for a near or complete cancellation of the axion-photon coupling constant. In this case there is no stellar-evolution limits on ma and for hadronic axions there exists a small window 10 eV ≤ ma ≤ 40 eV between supernova cooling and axion burst arguments. So far the best and only discussed candidate for hot dark matter has been the massive neutrino with a mass of a few eV. Because the Super-Kamiokande experiment suggests the tau neutrino mass of only 0.03-0.1 eV, the hadronic axion in the so-called hadronic axion window could be a good candidate for a cosmological hot dark matter within the mixed dark matter scenario. To verify this window one can search for axions by appealing only to their coupling to nucleons. The most promising methods are the observation of an axion burst from a future supernova and the resonant absorption of almost monochromatic solar axions. We have performed the first experiment along this new line of solar axion investigations. Using a small target of 0.03 g of 57Fe we have made a search for 14.4 keV gamma rays induced by resonant absorption of almost monochromatic solar axions. These Doppler broadened axions could be emitted from the Sun, in M1 transition between the first, thermally excited state and the ground state of 57Fe. An upper limit on hadronic axion mass of 745 eV is obtained at the 95 % confidence level. Search for solar axions is beginning to become
Nowakowski, Daniel; Kuster, Markus; Meister, Claudia V.; Fuelbert, Florian; Hoffmann, Dieter H.H. [TU Darmstadt (Germany). Institut fuer Kernphysik; Weiss, Achim [Max-Planck-Institut fuer Astrophysik, Garching (Germany)
2010-07-01
An axion helioscope is typically operated to observe the sun as an axion source. Additional pointings at celestial sources, e.g. stars in other galaxies, result in possible detections of axions from distant galactic objects. For the observation of supplementary axion sources we therefore calculate the thereotical axion flux from distant stars by extending axionic flux models for the axion Primakoff effect in the sun to other main sequence stars. The main sequence star models used for our calculations are based on full stellar structure calculations. To deduce the effective axion flux of stellar objects incident on the Earth the All-Sky catalogue was used to obtain the spectral class and distance of the stars treated. Our calculations of the axion flux in the galactic plane show that for a zero age main sequence star an maximum axion flux of {phi}{sub a}=303.43 cm{sup -2}s{sup -1} could be expected. Furthermore we present estimates of axion fluxes from time-evolved stars.
An axion helioscope is typically operated to observe the sun as an axion source. Additional pointings at celestial sources, e.g. stars in other galaxies, result in possible detections of axions from distant galactic objects. For the observation of supplementary axion sources we therefore calculate the thereotical axion flux from distant stars by extending axionic flux models for the axion Primakoff effect in the sun to other main sequence stars. The main sequence star models used for our calculations are based on full stellar structure calculations. To deduce the effective axion flux of stellar objects incident on the Earth the All-Sky catalogue was used to obtain the spectral class and distance of the stars treated. Our calculations of the axion flux in the galactic plane show that for a zero age main sequence star an maximum axion flux of Φa=303.43 cm-2s-1 could be expected. Furthermore we present estimates of axion fluxes from time-evolved stars.
CERN. Geneva
2005-01-01
A summary of the status of axions and axion-like particles will be given. Special attention is devoted to the recent results of the PVLAS collaboration, which are in conflict with CAST data and with astrophysical constraints. Solutions to this puzzle and the implications for new physics are dicussed. The subject of axion-like particles as dark matter will be included in the lecture. Finally some new results on new forces mediated by light scalars are debated.
Wilczek, Frank; Turner, Michael S.
1990-09-01
If Peccei-Quinn (PQ) symmetry is broken after inflation, the initial axion angle is a random variable on cosmological scales; based on this fact, estimates of the relic-axion mass density give too large a value if the axion mass is less than about 10-6 eV. This bound can be evaded if the Universe underwent inflation after PQ symmetry breaking and if the observable Universe happens to be a region where the initial axion angle was atypically small, .1 . (ma/10-6eV)0.59. We show consideration of fluctuations induced during inflation severely constrains the latter alternative.
CERN. Geneva
2016-01-01
Axions are a natural consequence of the Peccei-Quinn mechanism, the most compelling solution to the strong-CP problem. Similar axion-like particles (ALPs) also appear in a number of possible extensions of the Standard Model, notably in string theories. Both axions and ALPs are very well motivated candidates for the Dark Matter, and in addition would be copiously produced at the stellar cores. Some anomalous astrophysical observations could be hinting the existence of these particles. They are object of increasing interest by experimentalists. I will briefly review the motivation to search for axions and ALPs, as well as the current status and future prospects of the experimental landscape.
Future axion searches with the International Axion Observatory (IAXO)
Irastorza, I G; Avignone, F T; Cantatore, G;
2013-01-01
The International Axion Observatory (IAXO) is a new generation axion helioscope aiming at a sensitivity to the axion-photon coupling of gaγ (≳) few × 10−12 GeV−1, i.e. 1–1.5 orders of magnitude beyond the one achieved by CAST, currently the most sensitive axion helioscope. The main elements of IAXO...
Axions as Dark Matter Particles
Duffy, Leanne D.; Bibber, Karl van
2009-01-01
We review the current status of axions as dark matter. Motivation, models, constraints and experimental searches are outlined. The axion remains an excellent candidate for the dark matter and future experiments, particularly the Axion Dark Matter eXperiment (ADMX), will cover a large fraction of the axion parameter space.
Stern, I
2014-01-01
Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a $\\mu$eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 $\\mu$eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.
Minowa, M; Akimoto, Y; Ohta, R; Mizumoto, T; Yamamoto, A
2008-01-01
A new search result of the Tokyo axion helioscope is presented. The axion helioscope consists of a dedicated cryogen-free 4T superconducting magnet with an effective length of 2.3 m and PIN photodiodes as x-ray detectors. Solar axions, if exist, would be converted into X-ray photons through the inverse Primakoff process in the magnetic field. Conversion is coherently enhanced even for massive axions by filling the conversion region with helium gas. The present third phase measurement sets a new limit of g_{a\\gamma\\gamma}<(5.6--13.4)\\times10^{-10} GeV^{-1} for the axion mass of 0.84
Peccei-Quinn symmetry with attendant axion is a most compelling, and perhaps the most minimal, extension of the standard model, as it provides a very elegant solution to the nagging strong CP-problem associated with the Θ vacuum structure of QCD. However, particle physics gives little guidance as to the axion mass; a priori, the plausible values span the range: 10/sup /minus/12/ eV /approx lt/ m/sub a/ /approx lt/ 106 eV, some 18 orders-of-magnitude. Axions have a host of interesting astrophysical and cosmological effects, including, modifying the evolution of stars of all types (our sun, red giants, white dwarfs, and neutron stars), contributing significantly to the mass density of the Universe today, and producing detectable line radiation through the decays of relic axions. Consideration of these effects has probed 14 orders-of-magnitude in axion mass, and has left open only two windows for further exploration: 10/sup /minus/6/ eV /approx lt/ m/sub a/ /approx lt/ 10/sup /minus/3/ eV and 1 eV /approx lt/ m/sub a/ /approx lt/ 5 eV (hadronic axions only). Both these windows are accessible to experiment, and a variety of very interesting experiments, all of which involve ''heavenly axions,'' are being planned or are underway. 58 refs., 6 figs., 1 tab
Baer, Howard
2015-01-01
The strong CP problem of QCD is at heart a problem of naturalness: why is the F\\tilde{F} term highly suppressed in the QCD Lagrangian when it seems necessary to explain why there are three and not four light pions? The most elegant solution posits a spontaneously broken Peccei-Quinn (PQ) symmetry which requires the existence of the axion field a. The axion field settles to the minimum of its potential thus removing the offensive term but giving rise to the physical axion whose coherent oscillations can make up the cold dark matter. Only now are experiments such as ADMX beginning to explore QCD axion parameter space. Since a bonafide scalar particle-- the Higgs boson-- has been discovered, one might expect its mass to reside at the axion scale f_a~ 10^{11} GeV. The Higgs mass is elegantly stabilized by supersymmetry: in this case the axion is accompanied by its axino and saxion superpartners. Requiring naturalness also in the electroweak sector implies higgsino-like WIMPs so then we expect mixed axion-WIMP dar...
Turner, M.S.
1989-04-01
Peccei-Quinn symmetry with attendant axion is a most compelling, and perhaps the most minimal, extension of the standard model, as it provides a very elegant solution to the nagging strong CP-problem associated with the THETA vacuum structure of QCD. However, particle physics gives little guidance as to the axion mass; a priori, the plausible values span the range: 10/sup /minus/12/ eV /approx lt/ m/sub a/ /approx lt/ 10/sup 6/ eV, some 18 orders-of-magnitude. Axions have a host of interesting astrophysical and cosmological effects, including, modifying the evolution of stars of all types (our sun, red giants, white dwarfs, and neutron stars), contributing significantly to the mass density of the Universe today, and producing detectable line radiation through the decays of relic axions. Consideration of these effects has probed 14 orders-of-magnitude in axion mass, and has left open only two windows for further exploration: 10/sup /minus/6/ eV /approx lt/ m/sub a/ /approx lt/ 10/sup /minus/3/ eV and 1 eV /approx lt/ m/sub a/ /approx lt/ 5 eV (hadronic axions only). Both these windows are accessible to experiment, and a variety of very interesting experiments, all of which involve ''heavenly axions,'' are being planned or are underway. 58 refs., 6 figs., 1 tab.
Axion-photon couplings in invisible axion models
We reexamine the axion-photon couplings in various invisible axion models motivated by the recent proposal of using optical interferometry at the ASST facility at the SSCL to search for the axion. We illustrate that the assignment of U(1)PQ charges for the fermion fields plays an important role in determining the couplings. Several simple nonminimal invisible axion models with suppressed and enhanced axion-photon couplings are constructed, respectively. We also discuss the implications of possible new experiments to detect solar axions by conversion to x rays in a static magnetic apparatus tracking the Sun
Towards a realistic axion star
Barranco, J
2008-01-01
In this work we estimate the radius and the mass of a self-gravitating system made of axions. The quantum axion field satisfies the Klein-Gordon equation in a curved space-time and the metric components of this space-time are solutions to the Einstein equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. As a first step towards an axion star we consider the up to the sixth term in the axion potential expansion. We found that axion stars would have masses of the order of asteroids and radius of the order of few centimeters.
The axion particle is the experimental consequence of a particular way to restore P conservation into the QCD theory. The standard axion phenomenology proceeds on a scale given by the electroweak symmetry breaking. Such an axion is ruled out experimentally. Recently, observation of monochromatic peaks in e± production in heavy-ion collisions at GSI Darmstadt has motivated some re-examination of the situation. There appears to be no way to save the notion of an axion at the electroweak scale. Furthermore, experiments with electron beam-dumps have proven, together with g-2 measurements that the GSI effect cannot be explained in terms of a fundamental particle coupled to the e+e- channel
Eby, Joshua; Suranyi, Peter; Wijewardhana, L C R
2016-01-01
Axion stars, gravitationally bound states of low-energy axion particles, have a maximum mass allowed by gravitational stability. Weakly bound states obtaining this maximum mass have sufficiently large radii such that they are dilute, and as a result, they are well described by a leading-order expansion of the axion potential. Heavier states are susceptible to gravitational collapse. Inclusion of higher-order interactions, present in the full potential, can give qualitatively different results in the analysis of collapsing heavy states, as compared to the leading-order expansion. In this work, we find that collapsing axion stars are stabilized by repulsive interactions present in the full potential, providing evidence that such objects do not form black holes. These dense configurations, which are the endpoints of collapse, have extremely high binding energy, and as a result, decay through number changing $3\\,a\\rightarrow a$ interactions with an extremely short lifetime.
Yang, Qiaoli
2015-01-01
Dark matter particles constitute $23\\%$ of the total energy density of our universe and their exact properties are still unclear besides that they must be very cold and weakly interacting with the standard model particles. Many beyond standard model theories provide proper candidates to serve as the dark matter. The axions were introduced to solve the strong CP problem and later turned out to be a very attractive dark matter candidate. In this paper, we briefly review the physics of axions an...
Many theoretically well-motivated extensions of the Standard Model of particle physics predict the existence of the axion and further ultralight axion-like particles. They may constitute the mysterious dark matter in the universe and solve some puzzles in stellar and high-energy astrophysics. There are new, relatively small experiments around the globe, which started to hunt for these elusive particles and complement the accelerator based search for physics beyond the Standard Model.
We propose a new field theory mechanism for generating an effective trans-Planckian decay constant from sub-Planckian ones. Using the minimal two axions and a hierarchy between two axion decay constants is sufficient for realizing inflation through non-perturbative effects only and with minimal tuning. The inflationary motion is kept entirely within a sub-Planckian domain. We outline possible strategies of embedding the model in a string theory setup.
Axions-motivation, limits and searches
The axion solution of the strong CP problem provides a number of possible windows to physics beyond the standard model, notably in the form of searches for solar axions and for galactic axion dark matter, but in a broader context also inspires searches for axion-like particles in pure laboratory experiments. We briefly review the motivation for axions, astrophysical limits, their possible cosmological role, and current searches for axions and axion-like particles
Anomaly mediation deformed by axion
We show that in supersymmetric axion models the axion supermultiplet obtains a sizable F-term due to a non-supersymmetric dynamics and it generally gives the gaugino masses comparable to the anomaly mediation contribution. Thus the gaugino mass relation predicted by the anomaly mediation effect can be significantly modified in the presence of axion to solve the strong CP problem
Future axion searches with the International Axion Observatory (IAXO)
Irastorza, I G; Cantatore, G; Carmona, J M; Caspi, S; Cetin, S A; Christensen, F E; Dael, A; Dafni, T; Davenport, M; Derbin, A V; Desch, K; Diago, A; Döbrich, B; Dudarev, A; Eleftheriadis, C; Fanourakis, G; Ferrer-Ribas, E; Galán, J; García, J A; Garza, J.G; Geralis, T; Gimeno, B; Giomataris, I; Gninenko, S; Gómez, H; Guendelman, E; Hailey, C J; Hiramatsu, T; Hoffmann, D H H; Horns, D; Iguaz, F J; Isern, J; Jakobsen, A C; Jaeckel, J; Jakovčić, K; Kaminski, J; Kawasaki, M; Krčmar, M; Krieger, C; Lakić, B; Lindner, A; Liolios, A; Luzón, G; Ortega, I; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Redondo, J; Ringwald, A; Russenschuck, S; Ruz, J; Saikawa, K; Savvidis, I; Sekiguchi, T; Shilon, I; Sikivie, P; Silva, H; Kate, H ten; Tomas, A; Troitsky, S; Vafeiadis, T; Bibber, K van; Vedrine, P; Villar, J A; Vogel, J K; Walckiers, L; Wester, W; Yildiz, S C; Zioutas, K
2013-01-01
The International Axion Observatory (IAXO) is a new generation axion helioscope aiming at a sensitivity to the axion-photon coupling of gaγ few × 10−12 GeV−1, i.e. 1–1.5 orders of magnitude beyond the one achieved by CAST, currently the most sensitive axion helioscope. The main elements of IAXO are an increased magnetic field volume together with extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested in CAST. Additional physics cases of IAXO could include the detection of electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) and other novel excitations at the low-energy frontier of elementary particle physics.
Future axion searches with the International Axion Observatory (IAXO)
The International Axion Observatory (IAXO) is a new generation axion helioscope aiming at a sensitivity to the axion-photon coupling of gaγ ∼> few × 10−12 GeV−1, i.e. 1–1.5 orders of magnitude beyond the one achieved by CAST, currently the most sensitive axion helioscope. The main elements of IAXO are an increased magnetic field volume together with extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested in CAST. Additional physics cases of IAXO could include the detection of electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) and other novel excitations at the low-energy frontier of elementary particle physics
Dark Matter in Axion Landscape
Daido, Ryuji; Kobayashi, Takeshi; Takahashi, Fuminobu
2016-01-01
If there are a plethora of axions in nature, they may have a complicated potential and create an axion landscape. We study a possibility that one of the axions is so light that it is cosmologically stable, explaining the observed dark matter density. In particular we focus on a case in which two (or more) shift-symmetry breaking terms conspire to make the axion sufficiently light at the potential minimum. In this case the axion has a flat-bottomed potential. In contrast to the case in which a...
Axion domain wall baryogenesis
Daido, Ryuji; Kitajima, Naoya [Department of Physics, Tohoku University,Sendai 980-8578 (Japan); Takahashi, Fuminobu [Department of Physics, Tohoku University,Sendai 980-8578 (Japan); Kavli IPMU, TODIAS, University of Tokyo,Kashiwa 277-8583 (Japan)
2015-07-28
We propose a new scenario of baryogenesis, in which annihilation of axion domain walls generates a sizable baryon asymmetry. Successful baryogenesis is possible for a wide range of the axion mass and decay constant, m≃10{sup 8}–10{sup 13} GeV and f≃10{sup 13}–10{sup 16} GeV. Baryonic isocurvature perturbations are significantly suppressed in our model, in contrast to various spontaneous baryogenesis scenarios in the slow-roll regime. In particular, the axion domain wall baryogenesis is consistent with high-scale inflation which generates a large tensor-to-scalar ratio within the reach of future CMB B-mode experiments. We also discuss the gravitational waves produced by the domain wall annihilation and its implications for the future gravitational wave experiments.
Dark Matter in Axion Landscape
Daido, Ryuji; Takahashi, Fuminobu
2016-01-01
If there are a plethora of axions in nature, they may have a complicated potential and create an axion landscape. We study a possibility that one of the axions is so light that it is cosmologically stable, explaining the observed dark matter density. In particular we focus on a case in which two (or more) shift-symmetry breaking terms conspire to make the axion sufficiently light at the potential minimum. In this case the axion has a flat-bottomed potential. In contrast to the case in which a single cosine term dominates the potential, the axion abundance as well as its isocurvature perturbations are significantly suppressed. This allows an axion with a rather large mass to serve as dark matter without fine-tuning of the initial misalignment, and further makes higher-scale inflation to be consistent with the scenario.
In this talk, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this axionic mirage mediation, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around 1010 GeV to 1012 GeV due to the supersymmetry breaking effects. The problems in the original mirage mediation such as the μ-problem and the moduli problem can be solved simultaneouly. Furthermore, in our model the axino, which is the superpartner of the axion, is the lightest sparticle.
Nakamura, Shuntaro; Yamaguchi, Masahiro
2008-01-01
In this talk, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this \\textit{axionic mirage mediation}, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around $10^{10}$ GeV to $10^{12}$ GeV due to the supersymmetry breaking effects. The problems in the original mirage mediation such as the $\\mu$-problem and the moduli problem can be solved simultaneouly. Furthermore, in our model the axino, which is the superpartner of the axion, is the lightest sparticle.
Brown, Jon; Shiu, Gary; Soler, Pablo
2016-01-01
The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.
Cosmological Consequences of String Axions
Axion fluctuations generated during inflation lead to isocurvature and non-Gaussian temperature fluctuations in the cosmic microwave background radiation. Following a previous analysis for the model independent string axion we consider the consequences of a measurement of these fluctuations for two additional string axions. We do so independent of any cosmological assumptions except for the axions being massless during inflation. The first axion has been shown to solve the strong CP problem for most compactifications of the heterotic string while the second axion, which does not solve the strong CP problem, obeys a mass formula which is independent of the axion scale. We find that if gravitational waves interpreted as arising from inflation are observed by the PLANCK polarimetry experiment with a Hubble constant during inflation of Hinf ∼> 1013 GeV the existence of the first axion is ruled out and the second axion cannot obey the scale independent mass formula. In an appendix we quantitatively justify the often held assumption that temperature corrections to the zero temperature QCD axion mass may be ignored for temperatures T ∼QCD
Eby, Joshua; Wijewardhana, L C R
2015-01-01
We investigate the decay of condensates of scalars in a field theory defined by $V({\\cal A})=m^2 f^2 [1-\\cos({\\cal A}/f)]$, where $m$ and $f$ are the mass and decay constant of the scalar field. An example of such a theory is that of the axion, in which case the condensates are called axion stars. The axion field, $\\cal A$, is self adjoint. As a result the axion number is not an absolutely conserved quantity. Therefore, axion stars are not stable and have finite lifetimes. Bound axions, localized on the volume of the star, have a coordinate uncertainty $\\Delta x \\sim R \\sim 1/(m_a \\Delta)$, where $R$ is the radius of the star and $\\Delta = \\sqrt{1-E_0^2/m_a^2}$. Here $m_a$ and $E_0$ are the mass and the ground state energy of the bound axion. Then the momentum distribution of axions has a width of $\\Delta p \\sim m_a\\Delta$. At strong binding, $\\Delta={\\cal O}(1)$, bound axions can easily transfer a sufficient amount of momentum to create and emit a free axion, leading to fast decay of the star with a transiti...
Cosmic Axion Bose-Einstein Condensation
Banik, Nilanjan; Sikivie, Pierre
2015-01-01
QCD axions are a well-motivated candidate for cold dark matter. Cold axions are produced in the early universe by vacuum realignment, axion string decay and axion domain wall decay. We show that cold axions thermalize via their gravitational self-interactions, and form a Bose-Einstein condensate. As a result, axion dark matter behaves differently from the other proposed forms of dark matter. The differences are observable.
Staff Association
2013-01-01
Well done to all runners, the fans and the organizers of this great race which took place on Thursday 23rd May! You were many to participate in the run or by supporting your colleagues. The Staff Association contributed with its team of runners and also with its information stall where you could meet with your delegates.
Axion inflation with cross-correlated axion isocurvature perturbations
Kadota, Kenji [Center for Theoretical Physics of the Universe, Institute for Basic Science,Daejeon 305-811 (Korea, Republic of); Kobayashi, Tatsuo [Department of Physics, Hokkaido University,Sapporo 060-0810 (Japan); Otsuka, Hajime [Department of Physics, Waseda University,Tokyo 169-8555 (Japan)
2016-01-25
We study the inflation scenarios, in the framework of superstring theory, where the inflaton is an axion producing the adiabatic curvature perturbations while there exists another light axion producing the isocurvature perturbations. We discuss how the non-trivial couplings among string axions can generically arise, and calculate the consequent cross-correlations between the adiabatic and isocurvature modes through concrete examples. Based on the Planck analysis on the generally correlated isocurvature perturbations, we show that there is a preference for the existence of the correlated isocurvature modes for the axion monodromy inflation while the natural inflation disfavors such isocurvature modes.
We consider the effect of free-streaming axion emission on numerical models for the cooling of the newly born neutron star associated with SN 1987A. We find that for an axion mass of greater than ∼10/sup -3/ eV, axion emission shortens the duration of the expected neutrino burst so significantly that it would be inconsistent with the neutrino observations made by the Kamiokande II and Irvine-Michigan-Brookhaven detectors. However, we have not investigated the possibility that axion trapping (which should occur for masses ≥0.02 eV) sufficiently reduces axion emission so that axion masses greater than ∼2 eV would be consistent with the neutrino observations
The effect of free-streaming axion emission on numerical models for the cooling of the newly born neutron star associated with SN1987A is considered. It is found that for an axion mass of greater than approximately 10 to the -3 eV, axion emission shortens the duration of the expected neutrino burst so significantly that it would be inconsistent with the neutrino observations made by the Kamiokande II and Irvine-Michigan-Brookhaven detectors. However, the possibility has not been investigated that axion trapping (which should occur for masses greater than or equal to 0.02 eV) sufficiently reduces axion emission so that axion masses greater than approximately 2 eV would be consistent with the neutrino observations
Axions and the anthropic principle
We consider the possibility that the axion density in the Universe today may be constrained by the anthropic requirement that life should have evolved. If this were the case, the force of the usual cosmological bound on the axion decay constant would be greatly lessened. However, we find no mechanism by which excessive axion energy density could prevent the condensation of matter into potentially life-nurturing structures
Experimental search for solar axions
A new technique has been used to search for solar axions using a single crystal germanium detector. It exploits the coherent conversion of axions into photons when their angle of incidence satisfies a Bragg condition with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of gαγγ -9 GeV-1, independent of axion mass up to ∼ 1 keV
The QCD axion from aligned axions and diphoton excess
Tetsutaro Higaki
2016-04-01
Full Text Available We argue that the QCD axion can arise from many aligned axions with decay constants much smaller than the conventional axion window. If the typical decay constant is of O(100 GeV to 1 TeV, one or more of the axions or saxions may account for the recently found diphoton excess at ∼750 GeV. Our scenario predicts many axions and saxions coupled to gluons with decay constants of order the weak scale, and therefore many collider signatures by heavy axions and saxions will show up at different energy scales. In particular, if the inferred broad decay width is due to multiple axions or saxions, a non-trivial peak structure may become evident when more data is collected. We also discuss cosmological implications of the aligned QCD axion scenario. In the Appendix we give a possible UV completion and argue that the high quality of the Peccei–Quinn symmetry is naturally explained in our scenario.
González-Díaz, Pedro F.
2004-01-01
The existence of phantom energy in a universe which evolves to eventually show a big rip doomsday is a possibility which is not excluded by present observational constraints. In this paper it is argued that the field theory associated with a simple quintessence model is compatible with a field definition that is interpretable in terms of a rank-3 axionic tensor field, whenever we consider a perfect-fluid equation of state that corresponds to the phantom energy regime. Explicit expressions for...
Magnetogenesis from axion inflation
Adshead, Peter; Scully, Timothy R; Sfakianakis, Evangelos I
2016-01-01
In this work we compute the production of magnetic fields in models of axion inflation coupled to the hypercharge sector of the Standard Model through a Chern-Simons interaction term. We make the simplest choice of a quadratic inflationary potential and use lattice simulations to calculate the magnetic field strength, helicity and correlation length at the end of inflation. For small values of the axion-gauge field coupling strength the results agree with no-backreaction calculations and estimates found in the literature. For larger couplings the helicity of the magnetic field differs from the no-backreaction estimate and depends strongly on the comoving wavenumber. We estimate the post-inflationary evolution of the magnetic field based on known results for the evolution of helical and non-helical magnetic fields. The magnetic fields produced by axion inflation with large couplings to $U(1)_Y$ can reach $B_{\\rm eff} \\gtrsim 10^{-16}\\, G$. This result is insensitive to the exact value of the coupling, as long ...
Staff Association
2011-01-01
The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf
Staff Association
2011-01-01
The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12·15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf
Level Crossing between QCD Axion and Axion-Like Particle
Daido, Ryuji; Takahashi, Fuminobu
2015-01-01
We study a level crossing between the QCD axion and an axion-like particle, focusing on the recently found phenomenon, the axion roulette, where the axion-like particle runs along the potential, passing through many crests and troughs, until it gets trapped in one of the potential minima. We perform detailed numerical calculations to determine the parameter space where the axion roulette takes place, and as a result domain walls are likely formed. The domain wall network without cosmic strings is practically stable, and it is nothing but a cosmological disaster. In a certain case, one can make domain walls unstable and decay quickly by introducing an energy bias without spoiling the Peccei-Quinn solution to the strong CP problem.
Axion experiment makes its debut
Dumé, Belle
2004-01-01
An experiment built from components recycled from other experiments has put new limits on the properties of particles that might be the "dark matter" that makes up about 25% of the universe. The CERN Axion Solar telescope (CAST) was built to search for exotic particles called axions that might be produced inside the sun (1 page)
Electromagnetic detector for relic axions
Axions are particles of small mass postulated to explain CP conservation in strong interactions. The predicted properties of axions provide an explanation for the early clustering of matter into galaxies, the mass in galactic halos, and the missing mass sufficient to close the universe. The interaction of axions with ordinary matter would be extremely weak, but axions should be detectable, because in a strong magnetic field relic axions of mass m/sub a/ would convert into microwave photons with frequency f=m/sub a/c2/h. Predictions for the frequency range from 3 and 24 GHz for relic axions which provide mass density sufficient to close the universe. We propose a laboratory search for relic axions. A specific experimental apparatus is described and system performance is estimated to illustrate the design principles. The microwave signal from axion conversion is produced in a 30 liter microwave cavity which contains dielectric phase shifting plates to give a quality factor (Q) greater than 106, and to provide the correct phasing of the microwave electric field throughout the cavity. The cavity is placed in an 8 Tesla superconducting magnet, and the signal is measured with a conventional microwave receiver employing a GaAs FET rf amplifier or Schottky diode mixer. The cavity, magnet and rf amplifier/mixer will operate at 40K, with noise temperature between 200K and 2000K. The system is equally effective in principle at all frequencies between 1 GHz and 100 GHz at which microwave receivers are available. The corresponding range of axion mass which can be covered is 4x10-6 eV to 4x10-4 eV. A search can be carried out over an octave of frequency in an observation time of three months with sufficient sensitivity to detect axions if they make up the galactic halo
Axion Dark Matter Detection using Atomic Transitions
Sikivie, P
2014-01-01
Dark matter axions may cause transitions between atomic states that differ in energy by an amount equal to the axion mass. Such energy differences are conveniently tuned using the Zeeman effect. It is proposed to search for dark matter axions by cooling a kilogram-sized sample to milliKelvin temperatures and count axion induced transitions using laser techniques. This appears an appropriate approach to axion dark matter detection in the $10^{-4}$ eV mass range.
Cosmological Constant and Axions in String Theory
Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC
2006-08-18
String theory axions appear to be promising candidates for explaining cosmological constant via quintessence. In this paper, we study conditions on the string compactifications under which axion quintessence can happen. For sufficiently large number of axions, cosmological constant can be accounted for as the potential energy of axions that have not yet relaxed to their minima. In compactifications that incorporate unified models of particle physics, the height of the axion potential can naturally fall close to the observed value of cosmological constant.
Although mirage mediation is one of the most plausible mediation mechanisms of supersymmetry breaking, it suffers from two crucial problems. One is the μ/Bμ problem, and the second is the cosmological one. The former stems from the fact that the B parameter tends to be comparable with the gravitino mass, which is 2 orders of magnitude larger than the other soft masses. The latter problem is caused by the decay of the modulus whose branching ratio into the gravitino pair is sizable. In this paper, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this axionic mirage mediation, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around 1010 GeV to 1012 GeV due to the supersymmetry breaking effects, and the μ problem can be solved naturally. Furthermore, in our model, the lightest supersymmetric particle (LSP) is the axino, that is, the superpartner of the axion. The overabundance of the LSPs due to decays of the modulus/gravitino, which is the most serious cosmological difficulty in the mirage mediation, can be avoided if the axino is sufficiently light. The next-LSPs (NLSPs) produced by the gravitino decay eventually decay into the axino LSPs, yielding the dominant component of the axinos remaining today. It is shown that the axino with a mass of O(100) MeV is naturally realized, which can constitute the dark matter of the Universe, with a free-streaming length of the order of 0.1 Mpc. The saxion, the real scalar component of the axion supermultiplet, can also be cosmologically harmless due to the dilution of the modulus decay. The lifetime of the NLSP is relatively long, but much shorter than 1 sec, when the big-bang nucleosynthesis commences. The decay of the NLSP would provide intriguing collider signatures
Nakamura, Shuntaro; Okumura, Ken-ichi; Yamaguchi, Masahiro
2008-01-01
In this talk, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this \\textit{axionic mirage mediation}, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around $10^{10}$ GeV to $10^{12}$ GeV due to the supersymmetry breaking effects. The problems in the original mirage mediation such as the $\\mu$-problem and the moduli problem can be solved simultaneouly. Furthermore, in our model the axino, which is the superpartner ...
Nakamura, Shuntaro; Yamaguchi, Masahiro
2008-01-01
Although the mirage mediation is one of the most plausible mediation mechanisms of supersymmetry breaking, it suffers from two crucial problems. One is the \\mu-/B \\mu-problem and the second is the cosmological one. The former stems from the fact that the B parameter tends to be comparable with the gravitino mass, which is two order of magnitude larger than the other soft masses. The latter problem is caused by the decay of the modulus whose branching ratio into the gravitino pair is sizable. In this paper, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this \\textit{axionic mirage mediation}, it is shown that the PQ symmetry breaking scale is dynamically determined around 10^{10-12} GeV due to the supersymmetry breaking effects, and the \\mu-problem can be solved naturally. Furthermore, in our model, the lightest supersymmetric particle (LSP) is the axino, that is the superpartner of the axion. The overabundance of the LSPs due to decays of modulus/gravitino, which is...
We illustrate, taking a top-down point of view, how axions and other very weakly interacting sub-eV particles (WISPs) arise in the course of compactification of the extra spatial dimensions in string/M-theory. (orig.)
Eclipses could clarify axion mystery
2007-01-01
"Physicists in Europe have proposed an outlandish experiment that could determine once and for all whether ultralight particles called axions - one of the leading candidates for dark matter - exist." (1/2 page)
Wilczek, F.
Recent developments in theories of monopoles and axions are summarized, along with several implications. Present day monopoles are relics of early Big Bang processes. The remaining flux may be too small to detect, unless a local enhancement exists, such as a monopole cloud orbiting the sun. The 10 to the 16th GeV inertia of monopoles would require trapping in a magnetic bottle by a specially designed spacecraft. Degenerate monopoles may participate in the strong interactions and may not conserve the baryon number during the interaction. Axions have been postulated as the dynamical theta-field which describes the overall phase of the quark mass matrix. Energy transfer in stars could be accounted for by axions. At high temperatures, such as during the Big Bang, the axion would lose its mass, but in later epochs would be invisible and could account for the missing mass of the universe.
Axions, majorons and neutrino masses
We point out that there is an intimate connection between the seesaw scale for the light neutrinos and the invisible axion scale based on a series of recent investigations on the neutrino masses and mixings within a class of realistic SO(10) models. We can then extend the standard model accordingly so that both the standard invisible axion and majoron can be treated in a naturally unified manner. 7 refs
Ultrasensitive Searches for the Axion
van Bibber, K A; Rosenberg, L J
2006-07-14
The axion, a hypothetical elementary particle arising from a compelling solution to the strong-CP problem, has eluded discovery for three decades. Experiments based on coherent axion-photon mixing in strong magnetic fields are just now reaching the sensitivity to detect it, either as the dark matter or as a component of the solar flux. Although of lower sensitivity, purely laboratory experiments hold potential for surprise.
Two applications of axion electrodynamics
Wilczek, Frank
1987-01-01
The equations of axion electrodynamics are studied. Variations in the axion field can give rise to peculiar distributions of charge and current. These effects provide a simple understanding of the fractional electric charge on dyons and of some recently discovered oddities in the electrodynamics of antiphase boundaries in PbTe. Some speculations regarding the possible occurrence of related phenomena in other solids are presented.
Backreacted Axion Field Ranges in String Theory
Baume, Florent
2016-01-01
String theory axions are interesting candidates for fields whose potential might be controllable over super-Planckian field ranges and therefore as possible candidates for inflatons in large field inflation. Axion monodromy scenarios are setups where the axion shift symmetry is broken by some effect such that the axion can traverse a large number of periods potentially leading to super-Planckian excursions. We study such scenarios in type IIA string theory where the axion shift symmetry is broken by background fluxes. In particular we calculate the backreaction of the energy density induced by the axion vacuum expectation value on its own field space metric. We find universal behaviour for all the compactifications studied where up to a certain critical axion value there is only a small backreaction effect. Beyond the critical value the backreaction is strong and implies that the proper field distance as measured by the backreacted metric increases at best logarithmically with the axion vev, thereby placing s...
Axion: Mass -- Dark Matter Abundance Relation
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.
Is the invisible hadronic axion always harmless
In the Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axion model, if the invisible axion is hadronized (i.e. if the axion is made to decouple from leptons at tree level), it will be accompanied by a visible real Goldstone boson which interacts with both leptons and quarks. Consequently, the Higgs field coupled to right-handed leptons must also couple to right-handed d- or μ-type quark singlets. Astrophysical bounds on viable hadronic axions are discussed
Experimental Searches for the Axion and Axion-like Particles
Graham, Peter W; Lamoreaux, Steven K; Lindner, Axel; van Bibber, Karl A
2016-01-01
Four decades after its prediction, the axion remains the most compelling solution to the Strong-CP problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing. This report reviews the experimental situation on several fronts. The microwave cavity experiment is making excellent progress in the search for dark matter axions in the microelectronvolt range and may be plausibly extended up to 100 mu eV. Within the past several years however, it has been realized that axions are pervasive throughout string theories, but with masses that fall naturally in the nanoelectronvolt range, for which a NMR-based search is under development. Searches for axions emitted from the Sun's burning core, and purely laboratory experiments based on photon regeneration have both made great strides in recent years, with ambitious projects proposed for the coming decade. Each of these campaigns has pushed the state of the art in technology, enabling large ga...
Interaction of axions with relativistic spinning particles
Popov, V. A.; Balakin, A. B.
2016-05-01
We consider a covariant phenomenological model, which describes an interaction between a pseudoscalar (axion) field and massive spinning particles. The model extends the Bagrmann-Michel-Telegdy approach in application to the axion electrodynamics. We present some exact solutions and discuss them in the context of experimental tests of the model and axion detection.
Active galaxies can make axionic dark energy
Dimopoulos, Konstantinos; Cormack, Sam
2016-01-01
AGN jets carry helical magnetic fields, which can affect dark matter if the latter is axionic. This preliminary study shows that, in the presence of strong helical magnetic fields, the nature of the axionic condensate may change and become dark energy. Such dark energy may affect galaxy formation and galactic dynamics, so this possibility should not be ignored when considering axionic dark matter.
Interaction of axions with relativistic spinning particles
Popov, V A
2016-01-01
We consider a covariant phenomenological model, which describes an interaction between a pseudoscalar (axion) field and massive spinning particles. The model extends the Bagrmann-Michel-Telegdy approach in application to the axion electrodynamics. We present some exact solutions and discuss them in the context of experimental tests of the model and axion detection.
Axion landscape and natural inflation
Multiple axions form a landscape in the presence of various shift symmetry breaking terms. Eternal inflation populates the axion landscape, continuously creating new universes by bubble nucleation. Slow-roll inflation takes place after the tunneling event, if a very flat direction with a super-Planckian decay constant arises due to the alignment mechanism. We study the vacuum structure as well as possible inflationary dynamics in the axion landscape scenario, and find that the inflaton dynamics is given by either natural or multi-natural inflation. In the limit of large decay constant, it is approximated by the quadratic chaotic inflation, which however is disfavored if there is a pressure toward shorter duration of inflation. Therefore, if the spectral index and the tensor-to-scalar ratio turn out to be different from the quadratic chaotic inflation, there might be observable traces of the bubble nucleation. Also, the existence of small modulations to the inflaton potential is a common feature in the axion landscape, which generates a sizable and almost constant running of the scalar spectral index over CMB scales. Non-Gaussianity of equilateral type can also be generated if some of the axions are coupled to massless gauge fields
The axion mass in modular invariant supergravity
When supersymmetry is broken by condensates with a single condensing gauge group, there is a nonanomalous R-symmetry that prevents the universal axion from acquiring a mass. It has been argued that, in the context of supergravity, higher dimension operators will break this symmetry and may generate an axion mass too large to allow the identification of the universal axion with the QCD axion. We show that such contributions to the axion mass are highly suppressed in a class of models where the effective Lagrangian for gaugino and matter condensation respects modular invariance (T-duality)
Theory of Light Scattering in Axion Electrodynamics
Ochiai, Tetsuyuki
2012-09-01
Taking account of the axion term in the Maxwell Lagrangian, we present a rigorous theory of light scattering in piecewise-constant axion fields. In particular, we focus on axionic substances with confined and/or curved geometries, and the scattering matrices of an axionic slab, cylinder, and sphere are derived analytically. The axion term generates a surface current with off-diagonal optical conductivity, giving rise to a new type of photospin--orbit interaction. As a result, various novel light-scattering phenomena can take place. We demonstrate enhanced Faraday rotation, parity-violating light scattering, and strong perturbation of dipole radiation.
Axion dark matter: strings and their cores
Fleury, Leesa [McGill University, Department of Physics,3600 rue University, Montréal QC H3A 2T8 (Canada); Moore, Guy D. [Institut für Kernphysik, Technische Universität Darmstadt,Schlossgartenstraße 2, D-64289 Darmstadt (Germany)
2016-01-04
Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density of the network has little impact on the axion production efficiency.
Backreacted axion field ranges in string theory
Baume, Florent; Palti, Eran
2016-08-01
String theory axions are interesting candidates for fields whose potential might be controllable over super-Planckian field ranges and therefore as possible candidates for inflatons in large field inflation. Axion monodromy scenarios are setups where the axion shift symmetry is broken by some effect such that the axion can traverse a large number of periods potentially leading to super-Planckian excursions. We study such scenarios in type IIA string theory where the axion shift symmetry is broken by background fluxes. In particular we calculate the backreaction of the energy density induced by the axion vacuum expectation value on its own field space metric. We find universal behaviour for all the compactifications studied where up to a certain critical axion value there is only a small backreaction effect. Beyond the critical value the backreaction is strong and implies that the proper field distance as measured by the backreacted metric increases at best logarithmically with the axion vev, thereby placing strong limitations on extending the field distance any further. The critical axion value can be made arbitrarily large by the choice of fluxes. However the backreaction of these fluxes on the axion field space metric ensures a precise cancellation such that the proper field distance up to the critical axion value is flux independent and remains sub-Planckian. We also study an axion alignment scenario for type IIA compactifications on a twisted torus with four fundamental axions mixing to leave an axion with an effective decay constant which is flux dependent. There is a choice of fluxes for which the alignment parameter controlling the effective decay constant is unconstrained by tadpoles and can in principle lead to an arbitrarily large effective decay constant. However we show that these fluxes backreact on the fundamental decay constants so as to precisely cancel any enhancement leaving a sub-Planckian effective decay constant.
Staff Association
2012-01-01
The CERN Relay Race will take place around the Meyrin site on Thursday 24th May at 12:00. This annual event is for teams of six runners covering distances of 1000 m, 800 m, 800 m, 500 m, 500 m and 300 m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. There will also this year be a Nordic Walking event, as part of the Medical Service’s initiative “Move more, eat better!” The registration fee is 10 CHF per runner, and each runner will receive a souvenir prize. There will be a programme of entertainment from 12:00 on the arrival area (the lawn in front of Restaurant 1): 12:00 - 12:45 Music from the Old Bottom Street band 12:15 Start of the race 12:45 - 13h Demonstrations by the Fitness club and Dancing club 13:00 Results and prize giving (including a raffle to win an iPad2 3G offered by the Micro club) 13:20 à 14:00 Music from “What’s next” And many information st...
Magnetic Scope Angles for Axions
Seife, Charles
2005-01-01
After 2 years of staring at the sun, an unconventional "telescope" made from a leftover magnet has returned its first results. Although it hasn't yet found the quarry it was designed to spot - a particle that might or might not exist physicists say the CERN Axion Solar Telescope (CAST) is beginning to glimpse uncharted territory
Ultrasensitive searches for the axion
Van Bibber, Karl
2006-01-01
"The axion is a hypothetical particle with a mass possibly a trillion times lighter than an electron and exceedingly small couplings to ordinary matter. Yet experiments may soon detect its presence, either as dark matter or as a component of solar flux." (6 pages)
Axion Cooling of Neutron Stars
Sedrakian, Armen
2015-01-01
Cooling simulations of neutron stars and their comparison with the data from thermally emitting X-ray sources puts constraints on the properties of axions, and by extension of any light pseudo-scalar dark matter particles, whose existence has been postulated to solve the strong-CP problem of QCD. We incorporate the axion emission by pair-breaking and formation processes by $S$- and $P$-wave nucleonic condensates in a benchmark code for cooling simulations as well as provide fit formulae for the rates of these processes. Axion cooling of neutron stars has been simulated for 24 models covering the mass range 1 to 1.8 solar masses, featuring non-accreted iron and accreted light element envelopes, and a range of nucleon-axion coupling. The models are based on an equation state predicting conservative physics of superdense nuclear matter that does not allow for onset of fast cooling processes induced by phase transitions to non-nucleonic forms of matter or high proton concentration. The cooling tracks in the tempe...
Axion-Assisted Electroweak Baryogenesis
Craig, Nathaniel
2010-01-01
We consider a hidden-valley gauge sector, G, with strong coupling scale Lambda~TeV and CP-violating topological parameter, theta, as well as a new axion degree of freedom which adjusts theta to near zero in the current universe. If the G-sector couples to the Standard Model via weak-scale states charged under both, then in the early universe it is possible for the CP-violation due to theta (which has not yet been adjusted to zero by the hidden axion) to feed in to the SM and drive efficient baryogenesis during the electroweak (EW) phase transition, independent of the effectively small amount of CP violation present in the SM itself. While current constraints on both the new axion and charged states are easily satisfied, we argue that the LHC can investigate the vast majority of parameter space where EW-baryogenesis is efficiently assisted, while the hidden axion should comprise a significant fraction of the dark matter density. In the supersymmetric version, the ``messenger'' matter communicating between the ...
Axion overview and the U.S. RF cavity axion search
Rosenberg, L.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States); van Bibber, K.A.
1998-01-01
The axion, a hypothetical elementary particle, originally emerged from a solution to the strong CP problem in QCD. Later, axions were recognized as good dark matter candidates. Dark matter axions have only feeble couplings to matter and radiation, so their detection offers considerable challenge. Nonetheless, a new generation of exquisitely sensitive searches is underway. One such effort, in the United States, has already achieved sensitivity to plausible halo dark matter axion to photon couplings.
CERN Running Club
2010-01-01
The CERN relay race will take place around the Meyrin site on Thursday 20 May, starting at 12.15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the route, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay
2009-01-01
The CERN relay race will take place around the Meyrin site on Thursday 14th May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. More details on how to register your team for the relay race
CAST-CERN Axion Solar Telescope
CAST (CERN Axion Solar Telescope) is a helioscope looking for axions coming from the solar core to the Earth. The experiment, located at CERN, is based on the Primakoff effect and uses a magnetic field of 9 T provided by a decommissioned LHC magnet. CAST is able to follow the Sun during sunrise and sunset and therefore three X-ray detectors are mounted on both ends of the magnet waiting for a photon from axion-to-photon conversion due to Primakoff effect. During its first phase, which concluded in 2004, CAST has been looking for axions with masses up to 0.02 eV. The second phase did already start and first data were taken in December 2005. CAST's second phase manages to reestablish the coherence needed to scan for axions with masses up to 0.83 eV by using a buffer gas. This enables the experiment to look into the theoretical regions for axions
Rotating Drops of Axion Dark Matter
Davidson, Sacha
2016-01-01
We consider how QCD axions produced by the misalignment mechanism could form galactic dark matter halos. We recall that stationary, gravitationally stable axion field configurations have the size of an asteroid with masses of order $10^{-13} $ solar masses (because gradient pressure is insufficient to support a larger object). We call such field configurations "drops". We explore whether rotating drops could be larger, and find that their mass could increase by a factor ~ 10. Remarkably this mass is comparable to the mass of miniclusters generated from misalignment axions in the scenario where the axion is born after inflation. We speculate that misalignment axions today are in the form of drops, contributing to dark matter like a distribution of asteroids (and not as a coherent oscillating background field). We consider some observational signatures of the drops, which seem consistent with a galactic halo made of axion dark matter.
Searching for Dark-Matter Axions
Rosenberg, Leslie
2016-03-01
The axion is a hypothetical elementary particle arising in the 1970's from an elegant solution to the Strong CP problem in Quantum Chromo Dynamics. Light QCD axions (masses technology has advanced to where such axions might be detected. Several large searches are in the construction and commissioning phase, with new projects in the development phase. There are also concepts for new detector technologies aimed at improving the sensitivity and axion mass-reach. These searches would have the potential to detect even the more pessimistically-coupled dark-matter axions should they contribute a fraction of the local Milky Way dark-matter halo. This talk discusses the dark-matter axion experimental landscape and the prospects for their discovery. Supported by the U.S. Department of Energy, Office of High Energy Physics.
On supersymmetric effective theories of axion
Higaki, Tetsutaro [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kitano, Ryuichiro [Tohoku Univ., Sendai (Japan). Dept. of Physics
2011-04-15
We study effective theories of an axion in spontaneously broken supersymmetric theories. We consider a system where the axion supermultiplet is directly coupled to a supersymmetry breaking sector whereas the standard model sector is communicated with those sectors through loops of messenger fields. The gaugino masses and the axion-gluon coupling necessary for solving the strong CP problem are both obtained by the same effective interaction. We discuss cosmological constraints on this framework. (orig.)
Dynamical Axion Field in Topological Magnetic Insulators
Li, Rundong; Jing WANG; Qi, Xiaoliang; Zhang, Shou-Cheng
2009-01-01
Axions are very light, very weakly interacting particles postulated more than 30 years ago in the context of the Standard Model of particle physics. Their existence could explain the missing dark matter of the universe. However, despite intensive searches, they have yet to be detected. In this work, we show that magnetic fluctuations of topological insulators couple to the electromagnetic fields exactly like the axions, and propose several experiments to detect this dynamical axion field. In ...
On supersymmetric effective theories of axion
We study effective theories of an axion in spontaneously broken supersymmetric theories. We consider a system where the axion supermultiplet is directly coupled to a supersymmetry breaking sector whereas the standard model sector is communicated with those sectors through loops of messenger fields. The gaugino masses and the axion-gluon coupling necessary for solving the strong CP problem are both obtained by the same effective interaction. We discuss cosmological constraints on this framework. (orig.)
Axion Dark Matter Detection with Cold Molecules
Graham, Peter W.; Rajendran, Surjeet
2011-01-01
Current techniques cannot detect axion dark matter over much of its parameter space, particularly in the theoretically well-motivated region where the axion decay constant f_a lies near the GUT and Planck scales. We suggest a novel experimental method to search for QCD axion dark matter in this region. The axion field oscillates at a frequency equal to its mass when it is a component of dark matter. These oscillations induce time varying CP-odd nuclear moments, such as electric dipole and Sch...
Axion induced oscillating electric dipole moments
Hill, Christopher T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2015-06-24
In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency m_{a} and strength ~ 10^{-32} e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.
Fast Radio Bursts from Axion Stars
Iwazaki, Aiichi
2014-01-01
Axions are one of the most promising candidates of dark matter. The axions have been shown to form miniclusters with masses $\\sim 10^{-12}M_{\\odot}$ and to become dominant component of dark matter. These axion miniclusters condense to form axion stars. We show a possible origin of fast radio bursts ( FRBs ) by assuming the axion stars being dark matter: FRBs arise from the collisions between the axion stars and neutron stars. The FRBs are caused by the rapid conversion of the axions into electromagnetic fields under strong magnetic fields. Electric fields are induced on the axion stars under strong magnetic fields of neutron stars. The electric fields parallel to the magnetic fields oscillate with a frequency and make electrons in atmospheres of neutron stars coherently oscillate. Thus, the coherent radiations are emitted. The observed frequencies ( $\\sim 1.4$GHz ) of the bursts are given by the axion mass $m_a$ such as $m_a/2\\pi\\simeq 2.3\\,\\mbox{GHz}\\,\\big(m_a/10^{-5}\\mbox{eV}\\big)$. The frequency is affecte...
Goh, Hock-Seng; /UC, Berkeley /LBL, Berkeley; Ibe, Masahiro; /SLAC
2009-06-19
Supersymmetric models with spontaneously broken approximate R-symmetry contains a light spin 0 particle, the R-axion. The properties of the particle can be a powerful probe of the structure of the new physics. In this paper, we discuss the possibilities of the R-axion detection at the LHC experiments. It is challenge to observe this light particle in the LHC environment. However, for typical values in which the mass of the R-axion is a few hundred MeV, we show that those particles can be detected by searching for displaced vertices from R-axion decay.
Prospects for the CERN Axion Solar Telescope Sensitivity to 14.4 keV Axions
Jakovcic, K; Aune, S; Avignone, F T; Barth, K; Belov, A; Beltrn, B; Bruninger, H; Carmona, J M; Cebrin, S; Collar, J I; Dafni, T; Davenport, M; Di Lella, L; Eleftheriadis, C; Fanourakis, G K; Ferrer-Ribas, E; Fischer, H; Franz, J; Friedrich, P; Geralis, T; Giomataris, Ioanis; Gninenko, S; Hasinoff, M D; Heinsius, F H; Hoffmann, Dieter H H; Irastorza, I G; Jacoby, J; Kang, D; Knigsmann, K; Kotthaus, R; Krcmar, M; Kousouris, a K; Kuster, M; Laki, B; Lasseur, C; Liolios, A; Ljubici, A; Lutz, G; Luzn, G; Miller, D W; Morales, A; Morales, J; Ortiz, A; Papaevangelou, T; Placci, A; Raffelt, G; Ruz, J; Riege, H; Semertzidis, Y K; Serpico, Pasquale Dario; Stewart, o L; Vieira, J D; Villar, J; Vogel, J; Walckiers, L; Zioutas, K; Jakovcic, Kresimir
2007-01-01
The CERN Axion Solar Telescope (CAST) is searching for solar axions using the 9.0 T strong and 9.26 m long transverse magnetic field of a twin aperture LHC test magnet, where axions could be converted into X-rays via reverse Primakoff process. Here we explore the potential of CAST to search for 14.4 keV axions that could be emitted from the Sun in M1 nuclear transition between the first, thermally excited state, and the ground state of 57Fe nuclide. Calculations of the expected signals, with respect to the axion-photon coupling, axion-nucleon coupling and axion mass, are presented in comparison with the experimental sensitivity.
Kamionkowski, Marc
1997-01-01
There is almost universal agreement among cosmologists that most of the matter in the Universe is dark, and there are very good reasons to believe that most of this dark matter must be nonbaryonic. The two leading candidates for this dark matter are axions and weakly-interacting massive particles (WIMPs), such as the neutralino in supersymmetric extensions of the standard model. I discuss the arguments for these two dark-matter candidates and review techniques for discovery of these dark-matt...
Axion mass limit from observations of the neutron star in Cassiopeia A
Leinson, Lev B., E-mail: leinson@yandex.ru [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation of the Russian Academy of Science (IZMIRAN), 142190 Troitsk, Moscow (Russian Federation)
2014-08-01
Direct Chandra observations of a surface temperature of isolated neutron star in Cassiopeia A (Cas A NS) and its cooling scenario which has been recently simultaneously suggested by several scientific teams put stringent constraints on poorly known properties of the superfluid neutron star core. It was found also that the thermal energy losses from Cas A NS are approximately twice more intensive than it can be explained by the neutrino emission. We use these unique data and well-defined cooling scenario to estimate the strength of KSVZ axion interactions with neutrons. We speculate that enlarged energy losses occur owing to emission of axions from superfluid core of the neutron star. If the axion and neutrino losses are comparable we find c{sub n}{sup 2}m{sub a}{sup 2}∼ 5.7× 10{sup -6} eV{sup 2}, where m{sub a} is the axion mass, and c{sub n} is the effective Peccei-Quinn charge of the neutron. (Given the QCD uncertainties of the hadronic axion models, the dimensionless constant c{sub n} could range from -0.05 to 0.14.)
Vacuum selection on axionic landscapes
Wang, Gaoyuan; Battefeld, Thorsten
2016-04-01
We compute the distribution of minima that are reached dynamically on multi-field axionic landscapes, both numerically and analytically. Such landscapes are well suited for inflationary model building due to the presence of shift symmetries and possible alignment effects (the KNP mechanism). The resulting distribution of dynamically reached minima differs considerably from the naive expectation based on counting all vacua. These differences are more pronounced in the presence of many fields due to dynamical selection effects: while low lying minima are preferred as fields roll down the potential, trajectories are also more likely to get trapped by one of the many nearby minima. We show that common analytic arguments based on random matrix theory in the large D-limit to estimate the distribution of minima are insufficient for quantitative arguments pertaining to the dynamically reached ones. This discrepancy is not restricted to axionic potentials. We provide an empirical expression for the expectation value of such dynamically reached minimas' height and argue that the cosmological constant problem is not alleviated in the absence of anthropic arguments. We further comment on the likelihood of inflation on axionic landscapes in the large D-limit.
X-ray optics for axion helioscopes
Jakobsen, Anders Clemen; Pivovaroff, Michael J.; Christensen, Finn Erland
2013-01-01
A method of optimizing grazing incidence x-ray coatings in ground based axion helioscopes is presented. Software has been been developed to find the optimum coating when taking both axion spectrum and Micromegas detector quantum efficiency into account. A comparison of the relative effective area...
Some Considerations About Podolsky-Axionic Electrodynamics
Gaete, Patricio(Departmento de Física and Centro Científico-Tecnológico de Valparaíso, Universidad Técnica Federico Santa María, Valparaiso, Chile)
2011-01-01
For a Podolsky-axionic electrodynamics, we compute the interaction potential within the structure of the gauge-invariant but path-dependent variables formalism. The result is equivalent to that of axionic electrodynamics from a new noncommutative approach, up to first order in $\\theta$.
Fleury, Leesa M.; Moore, Guy D.
2016-05-01
If the axion exists and if the initial axion field value is uncorrelated at causally disconnected points, then it should be possible to predict the efficiency of cosmological axion production, relating the axionic dark matter density to the axion mass. The main obstacle to making this prediction is correctly treating the axion string cores. We develop a new algorithm for treating the axionic string cores correctly in 2+1 dimensions. When the axionic string cores are given their full physical string tension, axion production is about twice as efficient as in previous simulations. We argue that the string network in 2+1 dimensions should behave very differently than in 3+1 dimensions, so this result cannot be simply carried over to the physical case. We outline how to extend our method to 3+1D axion string dynamics.
Fleury, Leesa M
2016-01-01
If the axion exists and if the initial axion field value is uncorrelated at causally disconnected points, then it should be possible to predict the efficiency of cosmological axion production, relating the axionic dark matter density to the axion mass. The main obstacle to making this prediction is correctly treating the axion string cores. We develop a new algorithm for treating the axionic string cores correctly in 2+1 dimensions. When the axionic string cores are given their full physical string tension, axion production is about twice as efficient as in previous simulations. We argue that the string network in 2+1 dimensions should behave very differently than in 3+1 dimensions, so this result cannot be simply carried over to the physical case. We outline how to extend our method to 3+1D axion string dynamics.
Fermion production during and after axion inflation
We study derivatively coupled fermions in axion-driven inflation, specifically mϕ2ϕ2 and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions
Oscillating Chiral Tensor Spectrum from Axionic Inflation
Obata, Ippei
2016-01-01
We study the axionic inflation with a modulated potential and examine if the primordial tensor power spectrum exhibits oscillatory feature, which is testable with future space-based gravitational wave experiments such as DECIGO and BBO. In the case of the single-field axion monodromy inflation, it turns out that it is difficult to detect the oscillation in the spectrum due to suppression of the sub-Planckian decay constant of axion. On the other hand, in the case of aligned chromo-natural inflation where the axion is coupled to a SU(2) gauge field, it turns out that the sizable oscillation in the tensor spectrum can occur due to the enhancement of chiral gravitational waves sourced by the gauge field. We expect that this feature will be a new probe to axion phenomenologies in early universe through the chiral gravitational waves.
A Search for Axions and massive neutrinos
2002-01-01
This experiment relies on the production of a strong, contamination free (10$ ^{-12} $) source of radioactive $^{125}$I at the ISOLDE facility. Technical developments to achieve the necessary beam intensity are in progress. \\\\ \\\\The possible emission of axions in the 35.5 keV M1 transition of the $^{125}$Te daughter isotope is searched for by the axion analogue of the Mössbauer effect, i.e. the axion resonance absorption in a $^{125}$Te resonance absorber. For this purpose all other radiation emitted from the source is shielded by a non-resonant absorber, which is transparent, however, to axions. The resonance absorption is detected by measurement of subsequently emitted X-rays. A sensitivity to the axion emission branching ratio in the nuclear decay of 10$ ^{-7} $ is strived for.
Fermion production during and after axion inflation
Adshead, Peter; Sfakianakis, Evangelos I. [Department of Physics, University of Illinois at Urbana-Champaign,Urbana, Illinois 61801 (United States)
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
Solar axion search with the CAST experiment
Arik, E; Autiero, D; Barth, K; Belov, A; Beltrán, B; Borghi, S; Boydag, F S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Di Lella, L; Dogan, O B; Eleftheriadis, C; Elias, N; Fanourakis, G K; Ferrer-Ribas, E; Fischer, H; Franz, J; Galan, J; Gazis, E; Geralis, T; Giomataris, Yu; Gninenko, S; Gomez, H; Hasinoff, M; Heinsius, F H; Hikmet, I; Hoffmann, D H H; Irastorza, I G; Jacoby, J; Jakovcic, K; Kang, D; Karageorgopoulou, T; Karuza, M; Königsmann, K C; Kotthaus, R; Krcmar, M; Kousouris, K; Kuster, M; Lakic, B; Lasseur, C; Liolios, A; Ljubcici, A; Lozza, V; Lutz, G; Luzón, G; Miller, D; Morales, J; Niinikoski, T; Nordt, A; Ortiz, A; Papaevangelou, T; Pivovaroff, M; Placci, A; Raiteri, G; Raffelt, G; Riege, H; Rodríguez, A; Ruz, J; Savvidis, I; Semertzidis, Y; Serpico, P; Solanki, S K; Soufli, R; Stewart, L; Tsagri, M; Van Bibber, K; Villar, J; Vogel, J; Walckiers, L; Zioutas, K
2008-01-01
The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipe of an LHC dipole. The analysis of the data recorded during the first phase of the experiment with vacuum in the magnet pipes has resulted in the most restrictive experimental limit on the coupling constant of axions to photons. In the second phase, CAST is operating with a buffer gas inside the magnet pipes in order to extent the sensitivity of the experiment to higher axion masses. We will present the first results on the $^4{He}$ data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the $^3{He}$ data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent $^3{He}$ run just started in March 2008.
Yang, Qiaoli
I started work on the field of dark matter and cosmology with Dr. Sikivie three years ago with a goal to distinguish observationally axions or axion-like particles (ALPs) from other dark matter candidates such as weakly interacting massive particles (WIMPs) and sterile neutrinos. The subject is exciting because if one can determine the identity of the dark matter, it will be a mile-stone of physics beyond the standard model. On the high energy frontier, the standard model with three generation fermions is firmly established. However, it is not complete because the theory does not contain a plausible dark matter candidate, with properties required from observation, and the theory has fine-tuning problems such as the strong CP problem. On the cosmology and astrophysics frontiers, new observations of the dynamics of galaxy clusters, the rotation curves of galaxies, the abundances of light elements, gravitational lensing, and the anisotropies of the CMBR reach unprecedented accuracy. They imply cold dark matter (CDM) is 23% of the total energy density of the universe. Although many "beyond the standard model" theories may provide proper candidates to serve as CDM particles, the axion is especially compelling because it not only serves as the CDM particle, but also solves the strong CP problem. The axion was initially motivated by the strong CP problem, namely the puzzle why there is no CP violation in the strong interactions. Peccei and Quinn solved the problem by introducing a new UPQ(1) symmetry, and later Weinberg and Wilczek pointed out that the spontaneous breaking of UPQ(1) symmetry leads to a new pseudoscalar particle, the axion[1][2][3]. Axion models were proposed in which the symmetry breaking scale may be much larger than the electroweak scale, in which case the axion is very light and couples extremely weakly to ordinary matter. Furthermore, it was realized [4] that the cold axions, produced by the misalignment mechanism during the QCD phase transition, have
Bose-Einstein Condensation of Dark Matter Axions
Sikivie, P.; Yang, Q.
2009-01-01
We show that cold dark matter axions thermalize and form a Bose-Einstein condensate. We obtain the axion state in a homogeneous and isotropic universe, and derive the equations governing small axion perturbations. Because they form a BEC, axions differ from ordinary cold dark matter in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microw...
Large Field Inflation from Axion Mixing
Shiu, Gary; Ye, Fang
2015-01-01
We study the general multi-axion systems, focusing on the possibility of large field inflation driven by axions. We find that through axion mixing from a non-diagonal metric on the moduli space and/or from St\\"uckelberg coupling to a U(1) gauge field, an effectively super-Planckian decay constant can be generated without the need of "alignment" in the axion decay constants. We also investigate the consistency conditions related to the gauge symmetries in the multi-axion systems, such as vanishing gauge anomalies and the potential presence of generalized Chern-Simons terms. Our scenario applies generally to field theory models whose axion periodicities are intrinsically sub-Planckian, but it is most naturally realized in string theory. The types of axion mixings invoked in our scenario appear quite commonly in D-brane models, and we present its implementation in type II superstring theory. Explicit stringy models exhibiting all the characteristics of our ideas are constructed within the frameworks of Type IIA ...
The Next Generation of Axion Helioscopes: The International Axion Observatory (IAXO)
Vogel, J.K.; Armengaud, E.; Avignone, F.T.;
2015-01-01
The International Axion Observatory (IAXO) is a proposed 4th-generation axion helioscope with the primary physics research goal to search for solar axions via their Primakoff conversion into photons of 1 – 10 keV energies in a strong magnetic field. IAXO will achieve a sensitivity to the axion......-photon coupling gaγ down to a few ×10−12 GeV−1 for a wide range of axion masses up to ∼ 0.25eV. This is an improvement over the currently best (3rd generation) axion helioscope, the CERN Axion Solar Telescope (CAST), of about 5 orders of magnitude in signal strength, corresponding to a factor ∼ 20 in the axion...... photon coupling. IAXO's sensitivity relies on the construction of a large superconducting 8-coil toroidal magnet of 20 m length optimized for axion research. Each of the eight 60cm diameter magnet bores is equipped with x-ray optics focusing the signal photons into ∼ 0.2cm2 spots that are imaged by very...
New potentials for string axion inflation
Kobayashi, Tatsuo; Oikawa, Akane; Otsuka, Hajime
2016-04-01
We propose a new type of axion inflation with complex structure moduli in the framework of type IIB superstring theory compactified on the Calabi-Yau manifold. The inflaton is identified as the axion for the complex structure moduli whose potential is originating from instantonic corrections appearing through the period vector of the mirror Calabi-Yau manifold. The axionic shift symmetry is broken down to the discrete one by the inclusion of the instantonic correction and certain three-form fluxes. Our proposed inflation scenario is compatible with Kähler moduli stabilization. We also study a typical reheating temperature in the case of complex structure moduli inflation.
A 2nd generation cosmic axion experiment
Hagmann, C; Stoeffl, W.; Van Bibber, K.; Daw, E.; Kinion, D.; Rosenberg, L; Sikivie, P.; Sullivan, N.; D. Tanner; Moltz, D.; Nezrick, F.; Turner, M; Golubev, N.; Kravchuk, L.
1995-01-01
An experiment is described to detect dark matter axions trapped in the halo of our galaxy. Galactic axions are converted into microwave photons via the Primakoff effect in a static background field provided by a superconducting magnet. The photons are collected in a high Q microwave cavity and detected by a low noise receiver. The axion mass range accessible by this experiment is 1.3-13 micro-eV. The expected sensitivity will be roughly 50 times greater than achieved by previous experiments i...
A 2nd generation cosmic axion experiment
Hagmann, C A; Van Bibber, K; Daw, E J; Kinion, D S; Rosenberg, L J; Sikivie, P; Sullivan, N; Tanner, D B; Moltz, D M; Nezrick, F A; Turner, M; Golubev, N A; Kravchuk, L V
1995-01-01
An experiment is described to detect dark matter axions trapped in the halo of our galaxy. Galactic axions are converted into microwave photons via the Primakoff effect in a static background field provided by a superconducting magnet. The photons are collected in a high Q microwave cavity and detected by a low noise receiver. The axion mass range accessible by this experiment is 1.3-13 micro-eV. The expected sensitivity will be roughly 50 times greater than achieved by previous experiments in this mass range. The assembly of the detector is well under way at LLNL and data taking will start in mid-1995.
Gravitational Waves from Axion Monodromy
Hebecker, Arthur; Rompineve, Fabrizio; Witkowski, Lukas T
2016-01-01
Large field inflation is arguably the simplest and most natural variant of slow-roll inflation. Axion monodromy may be the most promising framework for realising this scenario. As one of its defining features, the long-range polynomial potential possesses short-range, instantonic modulations. These can give rise to a series of local minima in the post-inflationary region of the potential. We show that for certain parameter choices the inflaton populates more than one of these vacua inside a single Hubble patch. This corresponds to a dynamical phase decomposition, analogously to what happens in the course of thermal first-order phase transitions. In the subsequent process of bubble wall collisions, the lowest-lying axionic minimum eventually takes over all space. Our main result is that this violent process sources gravitational waves, very much like in the case of a first-order phase transition. We compute the energy density and peak frequency of the signal, which can lie anywhere in the mHz-GHz range, possib...
2008-01-01
The CERN relay race will take place around the Meyrin site on Thursday 5 June starting at 12:15 p.m. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on how to register your team for the relay race are given on the Staff Association Bulletin web site. You can access the online registration form at: http://cern.ch/club-running-relay/form.html
2011-01-01
The CERN relay race will take place around the Meyrin site on Thursday 19 May starting at 12-15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details of the course and of how to register your team for the relay race can be found here. Some advice for all runners from the Medical Service can also be found here.
Axion monodromy inflation with sinusoidal corrections
Kobayashi, Tatsuo; Yamaguchi, Yuya
2014-01-01
We study the axion monodromy inflation with a non-perturbatively generated sinusoidal term. The potential form is a mixture between the natural inflation and the axion monodromy inflation potentials. The sinusoidal term is subdominant in the potential, but leaves significant effects on the resultant fluctuation generated during inflation. A larger tensor-to-scalar ratio can be obtained in our model. We study two scenarios, single inflation scenario and the double inflation scenario. In the first scenario, the axion monodromy inflation with a sufficient number of e-fold generates a larger tensor-to-scalar ratio about $0.1 - 0.15$ but also a tiny running of spectral index. In the second scenario of double inflation, axion monodromy inflation is its first stage and, we assume another inflation follows. In this case, our model can realize a larger tensor-to-scalar ratio and a large negative running of spectral index simultaneously.
Nonrelativistic Effective Field Theory for Axions
Braaten, Eric; Zhang, Hong
2016-01-01
Axions can be described by a relativistic field theory with a real scalar field $\\phi$ whose self-interaction potential is a periodic function of $\\phi$. Low-energy axions, such as those produced in the early universe by the vacuum misalignment mechanism, can be described more simply by a nonrelativistic effective field theory with a complex scalar field $\\psi$ whose effective potential is a function of $\\psi^*\\psi$. We determine the coefficients in the expansion of the effective potential to fifth order in $\\psi^*\\psi$ by matching low-energy axion scattering amplitudes. In order to describe a Bose-Einstein condensate of axions that is too dense to expand the effective potential in powers of $\\psi^*\\psi$, we develop a sequence of systematically improvable approximations to the effective potential that include terms of all orders in $\\psi^*\\psi$.
Cavity Microwave Searches for Cosmological Axions
CERN. Geneva
2005-01-01
The lecture will cover the searches for dark matter axions based on the microwave cavity experiment of Sikivie. The topics will begin with a brief overview of halo dark matter, and the axion as a candidate. The principle of resonant conversion of axions in an external magnetic field will be described, and practical considerations in optimizing the experiment as a signal-to-noise problem. A major focus of the lecture will be the two complementary strategies for ultra-low noise detection of the microwave photons - the "photon-as-wave" approach (i.e. conventional heterojunction amplifiers and soon quantum-limited SQUID devices), and "photon-as-particle" (i.e. Rydberg-atom single-quantum detection). Experimental results will be presented; these experiments have already reached well into the range of sensitivity to exclude plausible axion models, for limited ranges of mass. The lecture will conclude with a discussion of future plans and challenges for the microwave ca...
Dark-matter QCD-axion searches.
Rosenberg, Leslie J
2015-10-01
In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There's no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10(-(6-3)) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments
Gravity wave and model-independent axion
Kim, Jihn E
2016-01-01
In this short comment, we notice that the model-independent axion contribution to the graviton mass at just outside the Schwarzschild radius is completely negligible in GW150914. The model-independent axion contribution to the graviton mass at the order $10^{-22}\\,$eV might be possible for merger of black holes of mass of order $2\\times 10^{14}\\,$kg.
Youn, Sungwoo
2016-07-01
The axion, a hypothetical fundamental particle, was postulated as an attractive solution to the CP problem in quantum chromodynamics and believed to be an ideal candidate for the cold dark matter. The Center for Axion and Precision Physics Research of the Institute for Basic Science has launched a state of the art experiment to search for the hypothesised new particle using microwave resonant cavities. I will discuss R&D efforts at our center and plans for the experiment.
An experiment to search for galactic axions
Results are presented from a search for axions in the mass range of .51 X 10-5 to 1 X 10-5eV, which may make up the dark matter halo of the galaxy. The detector used in the search consists of a microwave cavity placed in the strong magnetic field of a superconducting solenoid magnet. The energy in the TM010 mode of the cavity is monitored by a sensitive microwave receiver as the frequency of the mode is swept. The predicted experimental signature of galactic halo axions is a narrow signal, with a Qa = f/Δf ∼ 3 X 106, which is expected when the resonant frequency of the cavity corresponds to the mass of the axion. An experimental limit on the coupling times the density of (gaγγ/ma)2 ρa ≤ 2 x 10-40 for an axion linewidth ≤ 400 Hz with a 97% confidence level has been obtained. The theoretical prediction is (gaγγ/ma)2ρa ∼ 3.9 x 10-44 with ρa = 300 MeV/cm3. The corresponding limit in gaγγ ≤ 7 x 10-14 GeV-1 at an axion frequency f = 2 GeV and depends linearly on axion mass
Black hole formation from axion stars
Helfer, Thomas; Clough, Katy; Fairbairn, Malcolm; Lim, Eugene A; Becerril, Ricardo
2016-01-01
The classical equations of motion for an axion with potential $V(\\phi)=m_a^2f_a^2 [1-\\cos (\\phi/f_a)]$ possess quasi-stable, localized, oscillating solutions, which we refer to as "axion stars". We study, for the first time, collapse of axion stars numerically using the full non-linear Einstein equations of general relativity and the full non-perturbative cosine potential. We map regions on an "axion star stability diagram", parameterized by the initial ADM mass, $M_{\\rm ADM}$, and axion decay constant, $f_a$. We identify three regions of the parameter space: i) long-lived oscillating axion star solutions, with a base frequency, $m_a$, modulated by self-interactions, ii) collapse to a BH and iii) complete dispersal due to gravitational cooling and interactions. We locate the boundaries of these three regions and an approximate "triple point" $(M_{\\rm TP},f_{\\rm TP})\\sim (2.4 M_{pl}^2/m_a,0.3 M_{pl})$. For $f_a$ below the triple point BH formation proceeds during winding (in the complex $U(1)$ picture) of the ...
Photon - axion conversions in a periodic electromagnetic field with axion frequency
The conversion of photons into axions in a periodic external electromagnetic field with axion frequency is considered in detail by Feynman methods. The differential cross sections are given. It is shown that there is a resonant conversion for the considered process. (author)
Conceptual design of the International Axion Observatory (IAXO)
Armengaud, E.; Avignone, F. T.; Betz, M.;
2014-01-01
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will...... be about 4–5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few × 10−12 GeV−1 and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive...... and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20 m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x...
Discovering the QCD Axion with Black Holes and Gravitational Waves
Arvanitaki, Asimina; Baryakhtar, Masha; Huang, Xinlu
2014-01-01
Advanced LIGO may be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom." Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angu...
Small field axion inflation with sub-Planckian decay constant
Kadota, Kenji; Oikawa, Akane; Omoto, Naoya; Otsuka, Hajime; Tatsuishi, Takuya H
2016-01-01
We study an axion inflation model recently proposed within the framework of type IIB superstring theory, where we pay a particular attention to a sub-Planckian axion decay constant. Our axion potential can lead to the small field inflation with a small tensor-to-scalar ratio, and a typical reheating temperature can be as low as GeV.
Running Club
2010-01-01
This year’s CERN Relay Race will take place around the Meyrin site on Thursday 20th May at 12h00. This annual event is for teams of 6 runners covering distances of 1000m, 800m, 800m, 500m, 500m and 300m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. The registration fee is 10 CHF per runner, and each runner receives a souvenir prize. As usual, there will be a programme of entertainments from 12h in the arrival area, in front of the Restaurant no. 1. Drinks, food, CERN club information and music will be available for the pleasure of both runners and spectators. The race starts at 12h15, with results and prize giving at 13:15. For details of the race, and of how to sign up a team, please visit: https://espace.cern.ch/Running-Club/CERN-Relay The event is organised by the CERN Running Club with the support of the CERN Staff Association.
Dynamical axion string, screw dislocation in Weyl semimetals and Axion insulators
You, Yi-Zhi; Cho, Gil Young; Hughes, Taylor
We study the interplay between the geometry and axion string resulting from a chiral symmetry breaking in 3D. The chiral symmetry is spontaneously broken by charge density wave (CDW) order parameter nesting two Weyl points, which turns it into an axion insulator. The phase fluctuation of the CDW order parameter acts as a dynamical axion field coupled to electromagnetic field via θF ∧ F term. When the axion insulator is coupled with the background geometry with torsional defects, i.e. screw dislocations, there is a novel interplay between the dislocation and the dynamical axion string. First, we show that the screw dislocation traps an axial charge. This then implies that if an axion string braids with a parallel screw dislocation, there is Berry phase accumulated during the braiding procedure. In addition, the cubic coupling between the axial current and the torsion bilinear shows the Berry phase accumulated by the three-loop braiding procedure, where we braid one dislocation loop around the other dislocation loop where the both are linked by an axion string loop. We also observe a chiral magnetic effect induced by a screw dislocation in the absence of chemical potential imbalance between Weyl points.
You, Yizhi; Cho, Gil Young; Hughes, Taylor L.
2016-08-01
In this paper, we investigate the theory of dynamical axion strings emerging from chiral symmetry breaking in three-dimensional Weyl semimetals. The chiral symmetry is spontaneously broken by a charge density wave (CDW) order which opens an energy gap and converts the Weyl semimetal into an axion insulator. Indeed, the phase fluctuations of the CDW order parameter act as a dynamical axion field θ (x ⃗,t ) and couple to electromagnetic field via Lθ=θ/(x ⃗,t ) 32 π2 ɛσ τ ν μFσ τFν μ. Additionally, when the axion insulator is coupled to deformations of the background geometry/strain fields via torsional defects, e.g., screw dislocations, there is interesting interplay between the crystal dislocations and dynamical axion strings. For example, the screw dislocation traps axial charge, and there is a Berry phase accumulation when an axion string (which carries axial flux) is braided with a screw dislocation. In addition, a cubic coupling between the axial current and the geometry fields is nonvanishing and indicates a Berry phase accumulation during a particular three-loop braiding procedure where a dislocation loop is braided with another dislocation and they are both threaded by an axion string. We also observe a chiral magnetic effect induced by a screw dislocation density in the absence of a nodal energy imbalance between Weyl points and describe an additional chiral geometric effect and a geometric Witten effect.
Axion from Quivers in Type II Superstrings
Belhaj, Adil; del Moral, Maria Pilar Garcia
2015-01-01
We investigate a string-inspired axion extension of the standard model obtained from Type II superstrings using quiver method. In the first part, we discuss intersecting Type IIA D6-branes wrapping non trivial 3-cycles in the presence of the Peccei-Quinn symmetry U(1)$_{PQ}$. Concretely, a complex scalar field $\\phi =\\rho exp(\\frac{i\\sigma}{f_{\\sigma}})$, where $\\sigma$ is a closed string axion generates a general fermion Yukawa coupling weighted by a flavor-dependent power $n_{f}$ taking specific values. Using string theory and standard model data, we find that the corresponding axion window is in the allowed range $10^{9}GeV\\leq f_{\\sigma}\\leq 10^{12}GeV $ matching with the recent cosmological results. Then, we extend these results to the case of the hyperbolic quiver whose the moduli is related to the stringy axion using root systems of ADE Lie algebras. For the hyperbolic quiver case, we observe that the closed axion decay constant becomes disentangled from the string scale.
Lattice QCD input for axion cosmology
Berkowitz, Evan; Rinaldi, Enrico
2015-01-01
One intriguing BSM particle is the QCD axion, which could simultaneously provide a solution to the Strong CP problem and account for some, if not all, of the dark matter density in the universe. This particle is a pNGB of the conjectured Peccei-Quinn (PQ) symmetry of the Standard Model. Its mass and interactions are suppressed by a heavy symmetry breaking scale, $f_a$, whose value is roughly greater than $10^{9}$ GeV (or, conversely, the axion mass, $m_a$, is roughly less than $10^4\\ \\mu \\text{eV}$). The density of axions in the universe, which cannot exceed the relic dark matter density and is a quantity of great interest in axion experiments like ADMX, is a result of the early-universe interplay between cosmological evolution and the axion mass as a function of temperature. The latter quantity is proportional to the second derivative of the QCD free energy with respect to the CP-violating phase, $\\theta$. However, this quantity is generically non-perturbative and previous calculations have only employed ins...
Axion-dilaton cosmology and dark energy
We discuss a class of flat FRW cosmological models based on D=4 axion-dilaton gravity universally coupled to cosmological background fluids. In particular, we investigate the possibility of recurrent acceleration, which was recently shown to be generically realized in a wide class of axion-dilaton models, but in absence of cosmological background fluids. We observe that, once we impose the existence of radiation - and matter - dominated earlier stages of cosmic evolution, the axion-dilaton dynamics is altered significantly with respect to the case of pure axion-dilaton gravity. During the matter dominated epoch the scalar fields remain either frozen, due to the large expansion rate, or enter a cosmological scaling regime. In both cases, oscillations of the effective equation of state around the acceleration boundary value are impossible. Models which enter an oscillatory stage in the low redshift regime, on the other hand, are disfavored by observations. We also comment on the viability of the axion-dilaton system as a candidate for dynamical dark energy. In a certain subclass of models, an intermediate scaling regime is succeeded by eternal acceleration. We also briefly discuss the issue of dependence on initial conditions. (orig.)
Coupled Boltzmann computation of mixed axion neutralino dark matter in the SUSY DFSZ axion model
The supersymmetrized DFSZ axion model is highly motivated not only because it offers solutions to both the gauge hierarchy and strong CP problems, but also because it provides a solution to the SUSY μ-problem which naturally allows for a Little Hierarchy. We compute the expected mixed axion-neutralino dark matter abundance for the SUSY DFSZ axion model in two benchmark cases—a natural SUSY model with a standard neutralino underabundance (SUA) and an mSUGRA/CMSSM model with a standard overabundance (SOA). Our computation implements coupled Boltzmann equations which track the radiation density along with neutralino, axion, axion CO (produced via coherent oscillations), saxion, saxion CO, axino and gravitino densities. In the SUSY DFSZ model, axions, axinos and saxions go through the process of freeze-in—in contrast to freeze-out or out-of-equilibrium production as in the SUSY KSVZ model—resulting in thermal yields which are largely independent of the re-heat temperature. We find the SUA case with suppressed saxion-axion couplings (ξ=0) only admits solutions for PQ breaking scale fa∼< 6× 1012 GeV where the bulk of parameter space tends to be axion-dominated. For SUA with allowed saxion-axion couplings (ξ =1), then fa values up to ∼ 1014 GeV are allowed. For the SOA case, almost all of SUSY DFSZ parameter space is disallowed by a combination of overproduction of dark matter, overproduction of dark radiation or violation of BBN constraints. An exception occurs at very large fa∼ 1015–1016 GeV where large entropy dilution from CO-produced saxions leads to allowed models
Dynamical Axion String, Torsion Defects in Axion Insulator and Weyl Semimetals
You, Yizhi; Hughes, Taylor L
2016-01-01
In this paper, we investigate the theory of dynamical axion string emerging from chiral symmetry breaking in three-dimensional Weyl semimetals. The chiral symmetry is spontaneously broken by a charge density wave (CDW) order which opens an energy gap and converts the Weyl semimetal into an axion insulator. Indeed, the phase fluctuations of the CDW order parameter act as a dynamical axion field $\\theta({\\vec{x}},t)$ and couples to electromagnetic field via $\\mathcal{L}_{\\theta}=\\frac{\\theta(\\vec{x},t)}{32\\pi^2} \\epsilon^{\\sigma\\tau\
Measuring a piecewise constant axion field in classical electrodynamics
Obukhov, Yuri N. [Institute for Theoretical Physics, University of Cologne, 50923 Cologne (Germany)]. E-mail: yo@thp.uni-koeln.de; Hehl, Friedrich W. [Institute for Theoretical Physics, University of Cologne, 50923 Cologne (Germany)
2005-06-27
In order to settle the problem of the 'Post constraint' in material media, we consider the propagation of a plane electromagnetic wave in a medium with a piecewise constant axion field. Although a constant axion field does not affect the wave propagation in a homogeneous medium, we show that the reflection and transmission of a wave at an interface between the two media is sensitive to the difference of the axion values. This observation can be used to determine experimentally the axion piece in matter despite the fact that a constant axion value does not contribute to the Maxwell equations.
Measuring a piecewise constant axion field in classical electrodynamics
Obukhov, Yu N; Obukhov, Yuri N.; Hehl, Friedrich W.
2005-01-01
In order to settle the problem of the "Post constraint" in material media, we consider the propagation of a plane electromagnetic wave in a medium with a piecewise constant axion field. Although a constant axion field does not affect the wave propagation in a homogeneous medium, we show that the reflection and transmission of a wave at an interface between the two media is sensitive to the difference of the axion values. This observation can be used to determine experimentally the axion piece in matter despite the fact that a constant axion value does not contribute to the Maxwell equations.
Constraining the Axion Portal with B -> K l+ l-
Freytsis, Marat; Thaler, Jesse
2009-01-01
We investigate the bounds on axion-like states from flavor-changing neutral current b->s decays, assuming the axion couples to the standard model through mixing with the Higgs sector. Such GeV-scale axions have received renewed attention in connection with observed cosmic ray excesses. We find that existing B->K l+ l- data impose stringent bounds on the axion decay constant in the multi-TeV range, relevant for constraining the "axion portal" model of dark matter. Such bounds also constrain light Higgs scenarios in the NMSSM. These bounds can be improved by dedicated searches in B-factory data and at LHCb.
SQUID-based Resonant Detection of Axion Dark Matter
Popov, Vladimir
2014-01-01
A new method for searching for Dark Matter axions is proposed. It is shown that a two-contact SQUID can detect oscillating magnetic perturbations induced by the axions in a strong inhomogeneous magnetic field. A resonant signal is a steplike response in the SQUID current-voltage characteristic at a voltage corresponding to the axion mass with a height depending on the axion energy density near the Earth. The proposed experimental technique appears to be sensitive to the axions with masses $m_a\\lesssim 10^{-4}$ eV, which is well-motivated by current researches both in cosmology and in particle physics.
Resonance detection of dark matter axions using a DC SQUID
Popov, V. A.
2016-02-01
A method for detecting dark matter axions in which a dc SQUID serves as a detector is proposed. The SQUID is shown to be able to detect the magnetic field perturbations induced by its interaction with axions. The resonance signal appears as a current step in the SQUID current-voltage characteristic. The voltage of the step corresponds to the axion mass, while its height depends on the axion energy density in near-Earth space. The proposed method is aimed at detecting axions with masses m a ≲ 10-4 eV, which are of interest for both cosmology and particle physics.
Axion searches at CERN with the CAST Telescope
al, C. Eleftheriadis et
2003-01-01
The CERN Axion Solar Telescope (CAST) searches for axions coming from photon to axion conversion in the sun's core, as stated by the Primakoff effect. Axions arise in particle physics as a consequence of the breaking of Peccei-Quinn symmetry which has been introduced as a solution to the strong CP problem. As cosmological axions they are candidates for at least some part of cold Dark Matter.They are also expected to be produced copiously in stellar interiors with energies as high as the therm...
Discrete Abelian gauge symmetries and axions
Honecker, Gabriele
2015-01-01
We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete Zn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/Z2N and T6/Z2xZ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent Z2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial Z3 charge.
Dimopoulos, Savas; Huang, Junwu; Marques-Tavares, Gustavo
2016-01-01
We present a model where the 750 GeV resonance plays a fundamental role as the QCD axion. Conformal dynamics and strong CP considerations account for the coincidence of the weak scale, the axion mass, and the scale of spontaneous PQ breaking. A benchmark minimal model predicts just a pseudoscalar color octet at 1 TeV and heavier colored states carrying a new strong force accessible at future hadron colliders. This model is predictive as after fixing the 750 GeV mass and the diphoton rate, there are only two free choices of hypercharge assignment which completely determine the mass, decay modes and widths of the axion and the color octet.
Nonminimal Einstein-Maxwell-Vlasov-axion model
Balakin, Alexander B; Zayats, Alexei E
2014-01-01
We establish a new self-consistent system of equations accounting for a nonminimal coupling of the cooperative gravitational, electromagnetic and pseudoscalar (axion) fields in a multi-component relativistic plasma. The axionic extension of the nonminimal Einstein-Maxwell-Vlasov theory is based on two consistent procedures. First, we use the Lagrange formalism to obtain nonminimal equations for the gravitational, electromagnetic and pseudoscalar fields with the additional sources generated in plasma. Second, we use the Vlasov version of the relativistic kinetic theory of the plasma, guided by the cooperative macroscopic electromagnetic, gravitational and axionic fields, to describe adequately the response of the plasma on the variations of these fields. In order to show the self-consistency of this approach we check directly the compatibility conditions for the master equations for the cooperative fields. Using these compatibility conditions we reconstruct the ponderomotive force, which acts on the plasma par...
Discrete Abelian gauge symmetries and axions
Honecker, Gabriele; Staessens, Wieland
2015-07-01
We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete ℤn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/ℤ2N and T6/ℤ2 × ℤ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent ℤ2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial ℤ3 charge.
Solitonic axion condensates modeling dark matter halos
Castañeda Valle, David, E-mail: casvada@gmail.com; Mielke, Eckehard W., E-mail: ekke@xanum.uam.mx
2013-09-15
Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose–Einstein type condensates could provide a viable soliton type interpretation of the DM ‘bullets’ observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein–Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two ‘lump’ type solitons. -- Highlights: •An axion model of dark matter is considered. •Collision of axion type solitons are studied in a two dimensional toy model. •Relations to dark matter collisions in galaxy clusters are proposed.
Astrophysical axion bounds diminished by screening effects
''Invisible axions'' could be produced in stellar interiors through Compton- and Primakoff-type photoproduction and through bremsstrahlung processes. We point out that in a plasma screening effects lead to important reductions of these emission rates. Limits on the axion mass and interaction strength are thereby relaxed to values less restrictive than limits previously thought to be firm. For the case of the Sun the Primakoff rate is reduced by two orders of magnitude. This process is the dominant emission mechanism for Kim-Shifman-Vainshtein-Zakharov- (KSVZ) type axions which do not couple directly to electrons. The mass limit is then relaxed by an order of magnitude to m/sub a/2β of the model equals unity. Our results can be easily translated to other hypothetical pseudoscalar particles if they are light compared with typical stellar temperatures
We study the dynamics of axion-like fields in F-theory and suggest that they can serve as inflatons in models of natural inflation. The axions arise from harmonic three-forms on the F-theory compactification space and parameterize a complex torus that varies over the geometric moduli space. In particular, this implies that the axion decay constants depend on the complex structure moduli that can be fixed by background fluxes. This might allow tuning them to be super-Planckian in a controlled way and allow for interesting single field inflationary models. We argue that this requires a localization of the three-forms near regions of strong string coupling, analogously to the reasoning that GUT physics requires the use of F-theory. These models can admit a tensor to scalar ratio r>0.1
The CERN axion solar telescope (CAST)
Aalseth, C E; Autiero, D; Avignone, F T; Barth, K; Bowyer, S M; Bräuninger, H; Brodzinski, R L; Carmona, J M; Cebrián, S; Celebi, G; Cetin, S A; Collar, J I; Creswick, R; Delbart, A; Delattre, M; Di Lella, L; De Oliveira, R; Eleftheriadis, C; Erdutan, N; Fanourakis, G K; Farach, H A; Fiorini, C; Geralis, T; Giomataris, Ioanis; Girard, T A; Gninenko, S N; Golubev, N A; Hasinoff, M D; Hoffmann, D; Irastorza, I G; Jacoby, J; Jeanneau, F; Knopf, M A; Kovzelev, A; Kotthaus, R; Krcmar, M; Krecak, Z; Lakic, B; Liolios, A; Ljubicic, A; Lutz, Gerhard; Longoni, A; Luzón, G; Mailov, A; Matveev, V A; Miley, H S; Morales, A; Morales, J; Mutterer, M; Nikolaidis, A; Nussinov, S; Ortiz, A; Pitts, W K; Placci, A; Postoev, V E; Raffelt, G G; Riege, H; Sampietro, M; Sarsa, M; Savvidis, I; Stipcevic, M; Thomas, C W; Thompson, R C; Valco, P; Villar, J A; Villierme, B; Walckiers, L; Wilcox, W; Zachariadou, K; Zioutas, Konstantin
2002-01-01
A decommissioned LHC test magnet is being prepared as the CERN Axion Solar Telescope (CAST) experiment. The magnet has a field of 9.6 Tesla and length of 10 meters. It is being mounted on a platform to track the sun over +-8 deg. vertically and +-45 deg. , horizontally. A sensitivity in axion-photon coupling g alpha gamma gamma < 5 x 10 sup - sup 1 sup 1 GeV sup - sup 1 can be reached for m subalpha <= 10 sup - sup 2 eV, and with a gas filled tube-can reach g alpha gamma gamma <= 10 sup - sup 1 sup 0 GeV sup - sup 1 for axion masses m subalpha < 2eV.
A Broadband Approach to Axion Dark Matter Detection
Kahn, Yonatan; Thaler, Jesse
2016-01-01
When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axion dark matter with masses in the range of 10^{-13} eV to 10^{-6} eV, particularly the QCD axion with a GUT-scale decay constant.
CAST constraints on the axion-electron coupling
Barth, K; Beltran, B; Bräuninger, H; Carmona, J M; Collar, J I; Dafni, T; Davenport, M; Di Lella, L; Eleftheriadis, C; Englhauser, J; Fanourakis, G; Ferrer-Ribas, E; Fischer, H; Franz, J; Friedrich, P; Galan, J; Garcia, J A; Geralis, T; Giomataris, I; Gninenko, S; Gomez, H; Hasinoff, M D; Heinsius, F H; Hoffmann, D H H; Irastorza, I G; Jacoby, J; Jakovcic, K; Kang, D; Königsmann, K; Kotthaus, R; Kousouris, K; Krcmar, M; Kuster, M; Lakic, B; Liolios, A; Ljubicic, A; Lutz, G; Luzon, G; Miller, D W; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Redondo, J; Riege, H; Rodriguez, A; Ruz, J; Savvidis, I; Semertzidis, Y; Stewart, L; Van Bibber, K; Vieira, J D; Villar, J A; Vogel, J K; Walckiers, L; Zioutas, K
2013-01-01
In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces a strong axion flux by bremsstrahlung, Compton scattering, and axio-recombination, the "BCA processes." Based on a new calculation of this flux, including for the first time axio-recombination, we derive limits on the axion-electron Yukawa coupling g_ae and axion-photon interaction strength g_ag using the CAST phase-I data (vacuum phase). For m_a < 10 meV/c2 we find g_ag x g_ae< 8.1 x 10^-23 GeV^-1 at 95% CL. We stress that a next-generation axion helioscope such as the proposed IAXO could push this sensitivity into a range beyond stellar energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission.
Axion searches at CERN with the CAST Telescope
Eleftheriadis, C; Arik, E; Autiero, D; Avignone, F T; Barth, K; Bingol, E; Bräuninger, H; Brodzinski, R L; Carmona, J M; Cebrián, S; Cetin, S A; Chesi, Enrico Guido; Cipolla, G; Collar, J I; Creswick, R; Dafni, T; Davenport, M; De Oliveira, R; Dedoussis, S; Delbart, A; Di Lella, L; Fanourakis, G K; Farach, H A; Fischer, H; Formenti, F; Geralis, T; Glomataris, I; Gninenko, S N; Goloubev, N; Hartmann, R; Hasinoff, M D; Hoffmann, D; Irastorza, I G; Jacoby, J; Kang, D; Königsmann, K C; Kotthaus, R; Krcmar, M; Kuster, M; Lakic, B; Liolios, A; Ljubicic, A; Lutz, Gerhard; Luzón, G; Miley, H S; Morales, A; Morales, L; Mutterer, M; Nikolaidis, A; Ortiz, A; Papaevangelou, T; Placci, A; Raffelt, Georg G; Riege, H; Sarsa, M; Savvidis, I; Schopper, R; Semertzidis, Y K; Spanos, V C; Vasilelou, V; Villar, José Angel; Vullierme, B; Walckiers, L; Zachariadou, K; Zioutas, Konstantin
2003-01-01
The CERN Axion Solar Telescope (CAST) searches for axions coming from photon to axion conversion in the sun's core, as stated by the Primakoff effect. Axions arise in particle physics as a consequence of the breaking of Peccei-Quinn symmetry which has been introduced as a solution to the strong CP problem. As cosmological axions they are candidates for at least some part of cold Dark Matter.They are also expected to be produced copiously in stellar interiors with energies as high as the thermal photons undergoing photon to axion conversion. In our sun the axion energy spectrum peaks at about 4.4 keV, extending up to 10 keV. CAST collected preliminary data in 2002 and data taking with its full capability will start in the beginning of 2003.
Cosmological Perturbations of Axion with a Dynamical Decay Constant
Kobayashi, Takeshi
2016-01-01
A QCD axion with a time-dependent decay constant has been known to be able to accommodate high-scale inflation without producing topological defects or too large isocurvature perturbations on CMB scales. We point out that a dynamical decay constant also has the effect of enhancing the small-scale axion isocurvature perturbations. The enhanced axion perturbations can even exceed the periodicity of the axion potential, and thus lead to the formation of axionic domain walls. Unlike the well-studied axionic walls, the walls produced from the enhanced perturbations are not bounded by cosmic strings, and thus would overclose the universe independently of the number of degenerate vacua along the axion potential.
Drifting oscillations in axion monodromy
We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.
Universal constraints on axions from inflation
Ferreira, R. Z.; Sloth, M. S.
2014-01-01
perturbations through this mechanism, larger than the vacuum ones, without violating the observational constraints unless we combine this mechanism with a curvaton or if the sigma field becomes heavy and decays during inflation. Even in this last case there are non-trivial constraints coming from the slow......-roll evolution of the curvature perturbation on super horizon scales which should be taken into account. We also comment on implications for inflationary models where axions play an important role as, for example, models of natural inflation where more than one axion are included and models where the curvaton is...
Non-Gaussianity from Axion Monodromy Inflation
Hannestad, Steen; Haugboelle, Troels; R. Jarnhus, Philip;
2010-01-01
We study the primordial non-Gaussinity predicted from simple models of inflation with a linear potential and superimposed oscillations. This generic form of the potential is predicted by the axion monodromy inflation model, that has recently been proposed as a possible realization of chaotic...... inflation in string theory, where the monodromy from wrapped branes extends the range of the closed string axions to beyond the Planck scale. The superimposed oscillations in the potential can lead to new signatures in the CMB spectrum and bispectrum. In particular the bispectrum will have a new distinct...
Conceptual Design of the International Axion Observatory (IAXO)
Armengaud, E; Betz, M; Brax, P; Brun, P; Cantatore, G; Carmona, J M; Carosi, G P; Caspers, F; Caspi, S; Cetin, S A; Chelouche, D; Christensen, F E; Dael, A; Dafni, T; Davenport, M; Derbin, A V; Desch, K; Diago, A; Döbrich, B; Dratchnev, I; Dudarev, A; Eleftheriadis, C; Fanourakis, G; Ferrer-Ribas, E; Galán, J; García, J A; Garza, J G; Geralis, T; Gimeno, B; Giomataris, I; Gninenko, S; Gómez, H; González-Díaz, D; Guendelman, E; Hailey, C J; Hiramatsu, T; Hoffmann, D H H; Horns, D; Iguaz, F J; Irastorza, I G; Isern, J; Imai, K; Jakobsen, A C; Jaeckel, J; Jakovčić, K; Kaminski, J; Kawasaki, M; Karuza, M; Krčmar, M; Kousouris, K; Krieger, C; Lakić, B; Limousin, O; Lindner, A; Liolios, A; Luzón, G; Matsuki, S; Muratova, V N; Nones, C; Ortega, I; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Redondo, J; Ringwald, A; Russenschuck, S; Ruz, J; Saikawa, K; Savvidis, I; Sekiguchi, T; Semertzidis, Y K; Shilon, I; Sikivie, P; Silva, H; Kate, H ten; Tomas, A; Troitsky, S; Vafeiadis, T; Bibber, K van; Vedrine, P; Villar, J A; Vogel, J K; Walckiers, L; Weltman, A; Wester, W; Yildiz, S C; Zioutas, K
2014-01-01
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few $\\times 10^{-12}$ GeV$^{-1}$ and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling $g_{ae}$ with sensitivity $-$for the first time$-$ to values of $g_{ae}$ not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, w...
Axion Dark Matter Detection with Cold Molecules
Graham, Peter W
2011-01-01
Current techniques cannot detect axion dark matter over much of its parameter space, particularly in the theoretically well-motivated region where the axion decay constant f_a lies near the GUT and Planck scales. We suggest a novel experimental method to search for QCD axion dark matter in this region. The axion field oscillates at a frequency equal to its mass when it is a component of dark matter. These oscillations induce time varying CP-odd nuclear moments, such as electric dipole and Schiff moments. The coupling between internal atomic fields and these nuclear moments gives rise to time varying shifts to atomic energy levels. These effects can be enhanced by using elements with large Schiff moments such as the light Actinides, and states with large spontaneous parity violation, such as molecules in a background electric field. The energy level shift in such a molecule can be ~ 10^-24 eV or larger. While challenging, this energy shift may be observable in a molecular clock configuration with technology pr...
Axion models with high scale inflation
Moroi, Takeo; Mukaida, Kyohei; Nakayama, Kazunori; Takimoto, Masahiro
2014-11-01
We revisit the cosmological aspects of axion models. In the high-scale inflation scenario, the Peccei-Quinn (PQ) symmetry is likely to be restored during/after inflation. If the curvature of the PQ scalar potential at the origin is smaller than its vacuum expectation value; for instance in a class of SUSY axion models, thermal inflation happens before the radial component of the PQ scalar (saxion) relaxes into the global minimum of the potential and the decay of saxion coherent oscillation would produce too much axion dark radiation. In this paper, we study how to avoid the overproduction of axion dark radiation with some concrete examples. We show that, by taking account of the finite-temperature dissipation effect appropriately, the overproduction constraint can be relaxed since the PQ scalar can take part in the thermal plasma again even after the PQ phase transition. We also show that it can be further relaxed owing to the late time decay of another heavy CP-odd scalar, if it is present.
Axion hot dark matter bounds after Planck
Archidiacono, Maria; Hannestad, Steen [Department of Physics and Astronomy, University of Aarhus DK-8000 Aarhus C (Denmark); Mirizzi, Alessandro [II. Institut für Theoretische Physik, Universität Hamburg Luruper Chaussee 149, D-22761 Hamburg (Germany); Raffelt, Georg [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, D-80805 München (Germany); Wong, Yvonne Y.Y., E-mail: archi@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: alessandro.mirizzi@desy.de, E-mail: raffelt@mpp.mpg.de, E-mail: yvonne.y.wong@unsw.edu.au [School of Physics, The University of New South Wales Sydney NSW 2052 (Australia)
2013-10-01
We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit m{sub a} < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, using CMB temperature and polarisation data from Planck and WMAP respectively, the halo matter power spectrum extracted from SDSS-DR7, and the local Hubble expansion rate H{sub 0} released by the Carnegie Hubble Program based on a recalibration of the Hubble Space Telescope Key Project sample. Leaving out the local H{sub 0} measurement relaxes the limit somewhat to 0.86 eV, while Planck+WMAP alone constrain the axion mass to 1.01 eV, the first time an upper limit on m{sub a} has been obtained from CMB data alone. Our axion limit is therefore not very sensitive to the tension between the Planck-inferred H{sub 0} and the locally measured value. This is in contrast with the upper limit on the neutrino mass sum, which we find here to range from Σ m{sub ν} < 0.27 eV at 95% C.L. combining all of the aforementioned observations, to 0.84 eV from CMB data alone.
Axion hot dark matter bounds after Planck
Archidiacono, Maria; Mirizzi, Alessandro; Raffelt, Georg; Wong, Yvonne Y Y
2013-01-01
We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit m_a < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, using CMB temperature and polarisation data from Planck and WMAP respectively, the halo matter power spectrum extracted from SDSS-DR7, and the local Hubble expansion rate H_0 released by the Carnegie Hubble Program based on a recalibration of the Hubble Space Telescope Key Project sample. Leaving out the local H_0 measurement relaxes the limit somewhat to 0.86 eV, while Planck+WMAP alone constrain the axion mass to 1.01 eV, the first time an upper limit on m_a has been obtained from CMB data alone. Our axion limit is therefore not very sensitive to the tension between the Planck-inferred H_0 and the locally measured value. This is in contrast with the upper limit on the neutrino m...
Axion Models with High Scale Inflation
Moroi, Takeo; Nakayama, Kazunori; Takimoto, Masahiro
2014-01-01
We revisit the cosmological aspects of axion models. In the high-scale inflation scenario, the Peccei-Quinn (PQ) symmetry is likely to be restored during/after inflation. If the curvature of the PQ scalar potential at the origin is smaller than its vacuum expectation value; for instance in a class of SUSY axion models, thermal inflation happens before the radial component of the PQ scalar (saxion) relaxes into the global minimum of the potential and the decay of saxion coherent oscillation would produce too much axion dark radiation. In this paper, we study how to avoid the overproduction of axion dark radiation with some concrete examples. We show that, by taking account of the finite-temperature dissipation effect appropriately, the overproduction constraint can be relaxed since the PQ scalar can take part in the thermal plasma again even after the PQ phase transition. We also show that it can be further relaxed owing to the late time decay of another heavy CP-odd scalar, if it is present.
Review of dark-matter axion experiments
van Bibber, K; Kinion, D
2000-08-30
We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a 'second-generation' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.
Particle physics footprints of the invisible axion
I discuss some particle physics expectations of a natural class of invisible axion models. These models require the presence of charged and neutral spin zero bosons of Fermi scale masses. Indeed, such excitations appear to be telltale signals for almost all viable cold dark matter scenarios. (orig.)
Cavity Microwave Searches for Cosmological Axions
Carosi, G; van Bibber, K
2007-01-22
This chapter will cover the search for dark matter axions based on microwave cavity experiments proposed by Pierre Sikivie. We will start with a brief overview of halo dark matter and the axion as a candidate. The principle of resonant conversion of axions in an external magnetic field will be described as well as practical considerations in optimizing the experiment as a signal-to-noise problem. A major focus of this chapter will be the two complementary strategies for ultra-low noise detection of the microwave photons--the 'photon-as-wave' approach (i.e. conventional heterojunction amplifiers and soon to be quantum-limited SQUID devices), and 'photon-as-particle' (i.e. Rydberg-atom single-quantum detection). Experimental results will be presented; these experiments have already reached well into the range of sensitivity to exclude plausible axion models, for limited ranges of mass. The section will conclude with a discussion of future plans and challenges for the microwave cavity experiment.
Heavy axion in asymptotically safe QCD
Kobakhidze, Archil
2016-01-01
Assuming QCD exhibits an interacting fixed-point behaviour in the ultraviolet regime, I argue that the axion can be substantially heavier than in the conventional case of asymptotically free QCD due to the enhanced contribution of small size instantons to its mass.
A decommissioned LHC model magnet as an axion telescope
The 8.4 T, 10 m long transverse magnetic field of a twin aperture LHC bending magnet can be utilized as a macroscopic coherent solar axion-to-photon converter. Numerical calculations show that the integrated time of alignment with the Sun would be 33 days/yr with the magnet on a tracking table capable of ±5 deg. in the vertical direction and ±40 deg. in the horizontal direction. The existing lower bound on the axion-to-photon coupling constant can be improved by a factor between 30 and 100 in 3 yr, i.e., gaγγ -11 GeV-1 for axion masses < or approx. 1 eV. This value falls within the existing open axion mass window. The same set-up can simultaneously search for low- and high-energy celestial axions, or axion-like particles, scanning the sky as the Earth rotates and orbits the Sun
Solar axion experiments using coherent Primakoff conversion in single crystals
The results of a 1.94 kg · y pilot search for solar axions with an ultralow background Ge detector are reviewed. The detection method is based on Bragg-coherent Primakoff conversion of axions into photons when the momentum vectors of the axion and photon satisfy the Bragg condition. The theory of the experiment are presented for Ge and Te02 crystals. Future prospects of large volume experiments are discussed
Small Instanton Contribution to the Axion Potential in Supersymmetric Models
Choi, Kiwoon; Kim, Hyungdo
1998-01-01
Small size QCD instantons may spoil the axion solution to the strong CP problem if QCD is not asymptotically free at high energy scales. We examine this issue in supersymmetric models using a manifestly supersymmetric scheme to compute the axion potential induced by small size instantons. Applying this scheme for a class of illustrative models, it is found that the resulting high energy axion potential is highly model-dependent, but suppressed by more powers of the soft supersymmetry breaking...
Axion oscillations and the quark-hadron phase transition
We consider the possibility that the quark-hadron phase transition occurs when the axion field passes through the minimum of its potential during its oscillation cycle. If this were to occur, the axion field would gain no energy from the associated increase in mass thus permitting the cosmological bound on the axion decay constant to be raised. However, we find that the probability of this happening is small. (orig.)
Accelerating dark-matter axion searches with quantum measurement technology
Zheng, Huaixiu; Silveri, Matti; Brierley, R. T.; Girvin, S. M.; Lehnert, K. W.
2016-01-01
The axion particle, a consequence of an elegant hypothesis that resolves the strong-CP problem of quantum chromodynamics, is a plausible origin for cosmological dark matter. In searches for axionic dark matter that detect the conversion of axions to microwave photons, the quantum noise associated with microwave vacuum fluctuations will soon limit the rate at which parameter space is searched. Here we show that this noise can be partially overcome either by squeezing the quantum vacuum using r...
The paradox of axions surviving primordial magnetic fields
Ahonen, J; Raffelt, G G; Ahonen, Jarkko; Enqvist, Kari; Raffelt, Georg
1995-01-01
In the presence of primordial magnetic fields the oscillating cosmic axion field drives an oscillating electric field. The ensuing dissipation of axions is found to be inversely proportional to the conductivity of the primordial plasma. This counterintuitive result is essentially equivalent to ``Zeno's paradox'' or the ``watched-pot effect'' of quantum mechanics. It implies that the standard predictions of the cosmic axion density remain unaltered even if primordial magnetic fields are strong.
Thermal axion constraints in non-standard thermal histories
Grin, Daniel; Smith, Tristan; Kamionkowski, Marc
2010-01-01
There is no direct evidence for radiation domination prior to big-bang nucleosynthesis, and so it is useful to consider how constraints to thermally-produced axions change in non-standard thermal histories. In the low-temperature-reheating scenario, radiation domination begins at temperatures as low as 1 MeV, and is preceded by significant entropy generation. Axion abundances are then suppressed, and cosmological limits to axions are significantly loosened. In a kination scenario, a more mode...
Search for Sub-eV Mass Solar Axions by the CERN Axion Solar Telescope with 3He Buffer Gas
The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV a aγ -10 GeV-1 at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to ma < or approx. 1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.
Natural inflation with multiple sub-Planckian axions
Choi, Kiwoon; Kim, Hyungjin; Yun, Seokhoon
2014-01-01
We extend the Kim-Nilles-Peloso (KNP) alignment mechanism for natural inflation to models with $N>2$ axions, which obtains a super-Planckian effective axion decay constant $f_{\\textrm{eff}}\\gg M_{Pl}$ through an alignment of the anomaly coefficients of multiple axions having sub-Planckian fundamental decay constants $f_0\\ll M_{Pl}$. The original version of the KNP mechanism realized with two axions requires that some of the anomaly coefficients should be of the order of $f_{\\textrm{eff}}/f_0$...
Results on axion physics from the CAST Experiment at CERN
Eleftheriadis, Christos A; Aune, S; Barth, K; Belov, A; Beltran, B; Bräuninger, H; Carmona, J; Cebrián, S; Collar, J I; Dafni, T; Davenport, M; Di Lella, L; Englhauser, J; Fanourakis, G K; Ferrer-Ribas, E; Fischer, H; Franz, J; Friedrich, P; Geralis, T; Giomataris, Ioanis; Gninenko, S; Gomez, H; Hasinoff, M; Heinsius, F H; Hoffmann, D H H; Irastorza, I G; Jacoby, J; Jakovcic, K; Kang, D; Königsmann, K C; Kotthaus, R; Krcmar, M; Kousouris, K; Kuster, M; Laki, B; Lasseur, C; Liolios, A; Ljubicic, cA; Lutz, G; Luzón, G; Miller, D; Morales, A; Morales, J; Nordt, A; Ortiz, A; Papaevangelou, T; Placci, A; Raffelt, G; Riege1, H; Rodríguez, A; Ruz, J; Savvidis, I; Semertzidis, Y K; Serpico, Pasquale Dario; Stewart, L; Villar, J; Vogel, J; Walckiers, L; Zioutas, K
2007-01-01
Axions are expected to be produced in the sun via the Primakoff process. They may be detected through the inverse process in the laboratory, under the influence of a strong magnetic field, giving rise to X-rays of energies in the range of a few keV. Such an Axion detector is the CERN Axion Solar Telescope (CAST), collecting data since 2003. Results have been published, pushing the axion-photon coupling g$_{a\\gamma}$ below the 10$^{-10}$ GeV$^{-1}$ limit at 95% CL, for axion masses less than 0.02 eV. This limit is nearly an order of magnitude lower than previous experimental limits and surpassed for the first time limits set from astrophysical arguments based on the energy-loss concept. The experiment is currently exploring axion masses in the range of 0.02 eV $< m_a <$ 1.1 eV. In the next run, currently under preparation, the axion mass explored will be extended up to the limit of 1.1 eV, testing for the first time the region of theoretical axion models with the axion helioscope method.
Constraining the Axion Portal with B -> K l+ l-
Freytsis, Marat; Ligeti, Zoltan; Thaler, Jesse
2009-01-01
We investigate the bounds on axionlike states from flavor-changing neutral current b->s decays, assuming the axion couples to the standard model through mixing with the Higgs sector. Such GeV-scale axions have received renewed attention in connection with observed cosmic ray excesses. We find that existing B->K l+ l- data impose stringent bounds on the axion decay constant in the multi-TeV range, relevant for constraining the "axion portal" model of dark matter. Such bounds also constrain lig...
Future cosmological sensitivity for hot dark matter axions
Archidiacono, Maria; Basse, Tobias; Hamann, Jan; Hannestad, Steen; Raffelt, Georg; Wong, Yvonne Y.Y
2015-01-01
We study the potential of a future, large-volume photometric survey to constrain the axion mass $m_a$ in the hot dark matter limit. Future surveys such as Euclid will have significantly more constraining power than current observations for hot dark matter. Nonetheless, the lowest accessible axion masses are limited by the fact that axions lighter than $\\\\sim 0.15$ eV decouple before the QCD epoch, assumed here to occur at a temperature $T_{\\\\rm QCD} \\\\sim 170$ MeV; this leaves an axion popula...
An improved cosmological bound on the thermal axion mass
Melchiorri, Alessandro; Mena Requejo, Olga; Slosar, Anze
2007-01-01
Relic thermal axions could play the role of an extra hot dark matter component in cosmological structure formation theories. By combining the most recent observational data we improve previous cosmological bounds on the axion mass m(a) in the so-called hadronic axion window. We obtain a limit on the axion mass m(a)< 0.42 eV at the 95% C.L. (m(a)< 0.72 eV at the 99% C.L.). A novel aspect of the analysis presented here is the inclusion of massive neutrinos and how they may affect the bound on t...
Discovering the QCD Axion with Black Holes and Gravitational Waves
Arvanitaki, Asimina; Huang, Xinlu
2014-01-01
Advanced LIGO will be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom." Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons produce observable gravitational wave signals. The signals are long-lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. We estimate O(1) transition events at aLIGO for an axion between 10^-11 and 10^-10 eV and up to 1000 annihilation events for an axion between 10^-13 and 10^-12 eV. Axion annihilations are particularly promising for much lighter masses at f...
Constraining axion dark matter with Big Bang Nucleosynthesis
We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN
Constraining axion dark matter with Big Bang Nucleosynthesis
Kfir Blum
2014-10-01
Full Text Available We show that Big Bang Nucleosynthesis (BBN significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of He4 during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.
Detecting ultralight axion dark matter wind with laser interferometers
Aoki, Arata; Soda, Jiro
2016-01-01
The ultralight axion with mass around $10^{-23}$ eV is known as a candidate of dark matter. A peculiar feature of the ultralight axion is oscillating pressure in time, which produces oscillation of gravitational potentials. Since the solar system moves through the dark matter halo at the velocity of about $v \\sim 300 \\, \\text{km} / \\text{s} = 10^{-3}$, there exists axion wind, which looks like scalar gravitational waves for us. Hence, there is a chance to detect ultralight axion dark matter w...
Axion star collisions with Neutron stars and Fast Radio Bursts
Raby, Stuart
2016-01-01
Axions may make a significant contribution to the dark matter of the universe. It has been suggested that these dark matter axions may condense into localized clumps, called "axion stars." In this paper we argue that collisions of dilute axion stars with neutron stars may be the origin of most of the observed fast radio bursts. This idea is a variation of an idea originally proposed by Iwazaki. However, instead of the surface effect of Iwazaki, we propose a perhaps stronger volume effect caused by the induced time dependent electric dipole moment of neutrons.
Coupled Boltzmann computation of mixed axion neutralino dark matter in the SUSY DFSZ axion model
Bae, Kyu Jung; Lessa, Andre; Serce, Hasan
2014-01-01
The supersymmetrized DFSZ axion model is highly motivated not only because it offers solutions to both the gauge hierarchy and strong CP problems, but also because it provides a solution to the SUSY mu problem which naturally allows for a Little Hierarchy. We compute the expected mixed axion-neutralino dark matter abundance for the SUSY DFSZ axion model in two benchmark cases-- a natural SUSY model with a standard neutralino underabundance (SUA) and an mSUGRA/CMSSM model with a standard overabundance (SOA). Our computation implements coupled Boltzmann equations which track the radiation density along with neutralino, axion (produced thermally (TH) and via coherent oscillations (CO)), saxion (TH- and CO-produced), axino and gravitino densities. In the SUSY DFSZ model, axions, axinos and saxions go through the process of freeze-in-- in contrast to freeze-out or out-of-equilibrium production as in the SUSY KSVZ model-- resulting in thermal yields which are largely independent of the re-heat temperature. We find ...
Mixed axion/neutralino dark matter in the SUSY DFSZ axion model
We examine mixed axion/neutralino cold dark matter production in the SUSY DFSZ axion model where an axion superfield couples to Higgs superfields. We calculate a wide array of axino and saxion decay modes along with their decay temperatures, and thermal and non-thermal production rates. For a SUSY benchmark model with a standard underabundance (SUA) of Higgsino-like dark matter (DM), we find for the PQ scale fa∼<1012 GeV that the DM abundance is mainly comprised of axions as the saxion/axino decay occurs before the standard neutralino freeze-out and thus its abundance remains suppressed. For 1012∼
Search for sub-ev mass solar axions by the cern axion solar telescope with he-3 buffer gas
Çetin, Serkant Ali; CAST Collaboration
2011-01-01
The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using He-3 as a buffer gas. At T = 1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with He-4. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV less than or similar to m(a) less than or similar to 0.64 eV. From the absence of excess x rays when the magnet was pointing to ...
Minimal Models for Axion and Neutrino
Ahn, Y H
2015-01-01
The PQ mechanism resolving the strong CP problem and the seesaw mechanism explaining the smallness of neutrino masses may be related in a way that the PQ symmetry breaking scale and the seesaw scale arise from a common origin. Depending on how the PQ symmetry and the seesaw mechanism are realized, one has different predictions on the color and electromagnetic anomalies which could be tested in the future axion dark matter search experiments. Motivated by this, we construct various PQ seesaw models which are minimally extended from the (non-) supersymmetric Standard Model and thus set up different benchmark points on the axion-photon-photon coupling in comparison with the standard KSVZ and DFSZ models.
Minimal models for axion and neutrino
Ahn, Y. H.; Chun, Eung Jin
2016-01-01
The PQ mechanism resolving the strong CP problem and the seesaw mechanism explaining the smallness of neutrino masses may be related in a way that the PQ symmetry breaking scale and the seesaw scale arise from a common origin. Depending on how the PQ symmetry and the seesaw mechanism are realized, one has different predictions on the color and electromagnetic anomalies which could be tested in the future axion dark matter search experiments. Motivated by this, we construct various PQ seesaw models which are minimally extended from the (non-) supersymmetric Standard Model and thus set up different benchmark points on the axion-photon-photon coupling in comparison with the standard KSVZ and DFSZ models.
Naturalness of the invisible axion model
We discuss the choice of parameters that is necessary to establish the enormous hierarchy between the doublet and singlet Higgs vacuum expectation values in the invisible axion model. We show that this choice is associated with an approximate symmetry of the theory, thus demonstrating that the hierarchy in this model is natural in the sense of 't Hooft. It is then shown that this choice also leads to the existence of Higgs particles with masses ∝MW, which is particularly relevant for invisible axion models featuring spontaneous CP-violation. We comment on how our conclusions are affected by the introduction of right-handed neutrinos with large Majorana masses within the context of the see-saw mechanism. (orig.)
Kyu Jung Bae
2015-07-01
Full Text Available A variety of supersymmetric models give rise to a split mass spectrumcharacterized by very heavy scalars but sub-TeV gauginos, usually with awino-like LSP. Such models predict a thermally-produced underabundance ofwino-like WIMP dark matter so that non-thermal DM production mechanisms arenecessary.We examine the case where theories with a wino-like LSP are augmented by aPeccei-Quinn sector including an axion-axino-saxion supermultiplet in either theSUSY KSVZ or SUSY DFSZ models and with/without saxion decays to axions/axinos.We show allowed ranges of PQ breaking scale f_a for various cases which aregenerated by solving the necessary coupled Boltzmann equations.We also present results for a model with radiatively-driven naturalnessbut with a wino-like LSP.
Relativistic axions from collapsing Bose stars
Levkov, D G; Tkachev, I I
2016-01-01
The substructures of light bosonic (axion-like) dark matter may condense into compact Bose stars. We study collapses of the critical-mass stars caused by attractive self-interaction of the axion-like particles and find that these processes proceed in an unexpected universal way. First, nonlinear self-similar evolution (similar to "wave collapse" in plasma physics) forces the particles to fall into the star center. Second, collisions in the dense center create an outgoing stream of mildly relativistic particles which carries away an essential part of the star mass. The collapse stops when the star remnant is no longer able to support the self-similar infall feeding the collisions. We shortly discuss possible astrophysical and cosmological implications of these phenomena.
Large volume axionic Swiss cheese inflation
Continuing with the ideas of (Section 4 of) [A. Misra, P. Shukla, Moduli stabilization, large-volume dS minimum without anti-D3-branes, (non-)supersymmetric black hole attractors and two-parameter Swiss cheese Calabi-Yau's, (arXiv: 0707.0105 [hep-th]), Nucl. Phys. B, in press], after inclusion of perturbative and non-perturbative α' corrections to the Kaehler potential and (D1- and D3-) instanton generated superpotential, we show the possibility of slow roll axionic inflation in the large volume limit of Swiss cheese Calabi-Yau orientifold compactifications of type IIB string theory. We also include one- and two-loop corrections to the Kaehler potential but find the same to be subdominant to the (perturbative and non-perturbative) α' corrections. The NS-NS axions provide a flat direction for slow roll inflation to proceed from a saddle point to the nearest dS minimum
Wilson, Fiona
2007-01-01
Using accounts of militant schoolteachers from a province in the central sierra of Peru, this article attempts to show how and why concepts of race and political commitment among teachers changed at three critical moments in Peruvian history: agrarian reform, mass unionisation, and Maoist...
Axion topological field theory of topological superconductors
Qi, Xiao-Liang; Witten, Edward; Zhang, Shou-Cheng
2012-01-01
Topological superconductors are gapped superconductors with gapless and topologically robust quasiparticles propagating on the boundary. In this paper, we present a topological field theory description of three-dimensional time-reversal invariant topological superconductors. In our theory the topological superconductor is characterized by a topological coupling between the electromagnetic field and the superconducting phase fluctuation, which has the same form as the coupling of "axions" with...
Conceptual design of the International Axion Observatory (IAXO)
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4–5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few × 10−12 GeV−1 and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling gae with sensitivity — for the first time — to values of gae not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20 m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x-ray optics, able to focus the signal photons into ∼ 0.2 cm2 spots that are imaged by ultra-low-background Micromegas x-ray detectors. The magnet is built into a structure with elevation and azimuth drives that will allow for solar tracking for ∼ 12 h each day
2009-01-01
Dating back nearly 2000 years, the ancient Chinese tradition of Dragon Boat Racing was originally a celebration that fell on the 5th day of the 5th lunar month as a gesture to please the Gods and bring forth necessary rains to cultivate the lands. Now the CERN Canoe and Kayak Club, too, participates in this tradition, though not so much to please the Gods on the ritualistic date, but to bring forth giant smiles on the faces of members. Dragon Boat Racing has been rising steadily in popularity in Europe since the mid nineties and with the great potential to host and promote Dragon Boat Racing in the Geneva area, the CERN Canoe and Kayak Club, has taken the initiative to bring the sport to the region. Some members of the Club traveled to Dole in June to participate in the Festival Dragon Boat 2009. Under perfect sunny conditions, the team triumphed in their first ever tournament, cruising to a convincing first place overall finish. T...
Multiverse Dark Matter: SUSY or Axions
D'Eramo, Francesco; Pappadopulo, Duccio
2014-01-01
The observed values of the cosmological constant {\\it and} the abundance of Dark Matter (DM) can be successfully understood, using certain measures, by imposing the anthropic requirement that density perturbations go non-linear and virialize to form halos. This requires a probability distribution favoring low amounts of DM, i.e. low values of the PQ scale $f$ for the QCD axion and low values of the superpartner mass scale $\\tilde{m}$ for LSP thermal relics. In theories with independent scanning of multiple DM components, there is a high probability for DM to be dominated by a single component. For example, with independent scanning of $f$ and $\\tilde{m}$, TeV-scale LSP DM and an axion solution to the strong CP problem are unlikely to coexist. With thermal LSP DM, the scheme allows an understanding of a Little SUSY Hierarchy with multi-TeV superpartners. Alternatively, with axion DM, PQ breaking before (after) inflation leads to $f$ typically below (below) the projected range of the current ADMX experiment of ...
Axion monodromy and the weak gravity conjecture
Axions with broken discrete shift symmetry (axion monodromy) have recently played a central role both in the discussion of inflation and the 'relaxion' approach to the hierarchy problem. We suggest a very minimalist way to constrain such models by the weak gravity conjecture for domain walls: While the electric side of the conjecture is always satisfied if the cosine-oscillations of the axion potential are sufficiently small, the magnetic side imposes a cutoff, Λ3∝mfMpl, independent of the height of these 'wiggles'. We compare our approach with the recent related proposal by Ibanez, Montero, Uranga and Valenzuela. We also discuss the non-trivial question which version, if any, of the weak gravity conjecture for domain walls should hold. In particular, we show that string compactifications with branes of different dimensions wrapped on different cycles lead to a 'geometric weak gravity conjecture' relating volumes of cycles, norms of corresponding forms and the volume of the compact space. Imposing this 'geometric conjecture', e.g. on the basis of the more widely accepted weak gravity conjecture for particles, provides at least some support for the (electric and magnetic) conjecture for domain walls.
Axion monodromy and the weak gravity conjecture
Hebecker, Arthur; Rompineve, Fabrizio; Westphal, Alexander
2016-04-01
Axions with broken discrete shift symmetry (axion monodromy) have recently played a central role both in the discussion of inflation and the `relaxion' approach to the hierarchy problem. We suggest a very minimalist way to constrain such models by the weak gravity conjecture for domain walls: while the electric side of the conjecture is always satisfied if the cosine-oscillations of the axion potential are sufficiently small, the magnetic side imposes a cutoff, Λ3 ˜ mf M pl, independent of the height of these `wiggles'. We compare our approach with the recent related proposal by Ibanez, Montero, Uranga and Valenzuela. We also discuss the non-trivial question which version, if any, of the weak gravity conjecture for domain walls should hold. In particular, we show that string compactifications with branes of different dimensions wrapped on different cycles lead to a `geometric weak gravity conjecture' relating volumes of cycles, norms of corresponding forms and the volume of the compact space. Imposing this `geometric conjecture', e.g. on the basis of the more widely accepted weak gravity conjecture for particles, provides at least some support for the (electric and magnetic) conjecture for domain walls.
Axion Monodromy and the Weak Gravity Conjecture
Hebecker, Arthur; Westphal, Alexander
2015-01-01
Axions with broken discrete shift symmetry (axion monodromy) have recently played a central role both in the discussion of inflation and the `relaxion' approach to the hierarchy problem. We suggest a very minimalist way to constrain such models by the weak gravity conjecture for domain walls: While the electric side of the conjecture is always satisfied if the cosine-oscillations of the axion potential are sufficiently small, the magnetic side imposes a cutoff, $\\Lambda^3 \\sim m f M_{pl}$, independent of the height of these `wiggles'. We compare our approach with the recent related proposal by Ibanez, Montero, Uranga and Valenzuela. We also discuss the non-trivial question which version, if any, of the weak gravity conjecture for domain walls should hold. In particular, we show that string compactifications with branes of different dimensions wrapped on different cycles lead to a `geometric weak gravity conjecture' relating volumes of cycles, norms of corresponding forms and the volume of the compact space. I...
Future cosmological sensitivity for hot dark matter axions
Archidiacono, Maria; Hamann, Jan; Hannestad, Steen; Raffelt, Georg; Wong, Yvonne Y Y
2015-01-01
We study the potential of a future, large-volume photometric survey to constrain the axion mass $m_a$ in the hot dark matter limit. Future surveys such as Euclid will have significantly more constraining power than current observations for hot dark matter. Nonetheless, the lowest accessible axion masses are limited by the fact that axions lighter than $\\sim 0.15$ eV decouple before the QCD epoch, assumed here to occur at a temperature $T_{\\rm QCD} \\sim 170$ MeV; this leaves an axion population of such low density that its late-time cosmological impact is negligible. For larger axion masses, $m_a \\gtrsim 0.15$ eV, where axions remain in equilibrium until after the QCD phase transition, we find that a Euclid-like survey combined with Planck CMB data can detect $m_a$ at very high significance. Our conclusions are robust against assumptions about prior knowledge of the neutrino mass. Given that the proposed IAXO solar axion search is sensitive to $m_a\\lesssim 0.2$ eV, the axion mass range probed by cosmology is n...
Black Hole Mergers and the QCD Axion at Advanced LIGO
Arvanitaki, Asimina; Dimopoulos, Savas; Dubovsky, Sergei; Lasenby, Robert
2016-01-01
In the next few years Advanced LIGO (aLIGO) may see gravitational waves (GWs) from thousands of black hole (BH) mergers. This marks the beginning of a new precision tool for physics. Here we show how to search for new physics beyond the standard model using this tool, in particular the QCD axion in the mass range ma ~ 10^-14 to 10^-10 eV. Axions (or any bosons) in this mass range cause rapidly rotating BHs to shed their spin into a large cloud of axions in atomic Bohr orbits around the BH, through the effect of superradiance. This results in a gap in the mass vs. spin distribution of BHs when the BH size is comparable to the axion's Compton wavelength. By measuring the spin and mass of the merging objects observed at LIGO, we could verify the presence and shape of the gap in the BH distribution produced by the axion. The axion cloud can also be discovered through the GWs it radiates via axion annihilations or level transitions. A blind monochromatic GW search may reveal up to 10^5 BHs radiating through axion ...
Cosmological problems with multiple axion-like fields
Incorporating the QCD axion and simultaneously satisfying current constraints on the dark matter density and isocurvature fluctuations requires non-minimal fine-tuning of inflationary parameters or the axion misalignment angle (or both) for Peccei-Quinn symmetry-breaking scales fa > 1012 GeV. To gauge the degree of tuning in models with many axion-like fields at similar symmetry-breaking scales and masses, as may occur in string theoretic models that include a QCD axion, we introduce a figure of merit F that measures the fractional volume of allowed parameter space: the product of the slow roll parameter ε and each of the axion misalignment angles, θ0. For a single axion, F∼−11 is needed to avoid conflict with observations. We show that the fine tuning of F becomes exponentially more extreme in the case of numerous axion-like fields. Anthropic arguments are insufficient to explain the fine tuning because the bulk of the anthropically allowed parameter space is observationally ruled out by limits on the cosmic microwave background isocurvature modes. Therefore, this tuning presents a challenge to the compatibility of string-theoretic models with light axions and inflationary cosmology
Cosmological problems with multiple axion-like fields
Mack, Katherine J.; Steinhardt, Paul J.
2011-05-01
Incorporating the QCD axion and simultaneously satisfying current constraints on the dark matter density and isocurvature fluctuations requires non-minimal fine-tuning of inflationary parameters or the axion misalignment angle (or both) for Peccei-Quinn symmetry-breaking scales fa > 1012 GeV. To gauge the degree of tuning in models with many axion-like fields at similar symmetry-breaking scales and masses, as may occur in string theoretic models that include a QCD axion, we introduce a figure of merit Script F that measures the fractional volume of allowed parameter space: the product of the slow roll parameter epsilon and each of the axion misalignment angles, θ0. For a single axion, Script Flesssim10-11 is needed to avoid conflict with observations. We show that the fine tuning of Script F becomes exponentially more extreme in the case of numerous axion-like fields. Anthropic arguments are insufficient to explain the fine tuning because the bulk of the anthropically allowed parameter space is observationally ruled out by limits on the cosmic microwave background isocurvature modes. Therefore, this tuning presents a challenge to the compatibility of string-theoretic models with light axions and inflationary cosmology.
Diluting the inflationary axion fluctuation by a stronger QCD in the early Universe
Kiwoon Choi
2015-11-01
Full Text Available We propose a new mechanism to suppress the axion isocurvature perturbation, while producing the right amount of axion dark matter, within the framework of supersymmetric axion models with the axion scale induced by supersymmetry breaking. The mechanism involves an intermediate phase transition to generate the Higgs μ-parameter, before which the weak scale is comparable to the axion scale and the resulting stronger QCD yields an axion mass heavier than the Hubble scale over a certain period. Combined with that the Hubble-induced axion scale during the primordial inflation is well above the intermediate axion scale at present, the stronger QCD in the early Universe suppresses the axion fluctuation to be small enough even when the inflationary Hubble scale saturates the current upper bound, while generating an axion misalignment angle of order unity.
Axion Haloscopes with Toroidal Geometry at CAPP/IBS
Ko, B R
2016-01-01
The present state of the art axion haloscope employs a cylindrical resonant cavity in a solenoidal field. We, the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) in Korea, are also pursuing halo axion discovery using this cylindrical geometry. However, the presence of end caps of cavities increases challenges as we explore higher frequency regions for the axion at above 2 GHz. To overcome these challenges we exploit a toroidal design of cavity and magnetic field. A toroidal geometry offers several advantages, two of which are a larger volume for a given space and greatly reduced fringe fields which interfere with our preamps, in particular the planned quantum-based devices. We introduce the concept of toroidal axion haloscopes and present ongoing research activities and plans at CAPP/IBS.
Detecting ultralight axion dark matter wind with laser interferometers
Aoki, Arata
2016-01-01
The ultralight axion with mass around $10^{-23}$ eV is known as a candidate of dark matter. A peculiar feature of the ultralight axion is oscillating pressure in time, which produces oscillation of gravitational potentials. Since the solar system moves through the dark matter halo at the velocity of about $v \\sim 300 \\, \\text{km} / \\text{s} = 10^{-3}$, there exists axion wind, which looks like scalar gravitational waves for us. Hence, there is a chance to detect ultralight axion dark matter with a wide mass range by using laser interferometer detectors. We calculate the detector signal induced by the oscillating pressure of the ultralight axion field, which would be detected by future laser interferometer experiments. We also argue that the detector signal can be enhanced due to the resonance in modified gravity theory explaining the dark energy.
Search for Solar Axions with the CCD Detector and X-ray Telescope at CAST Experiment
Rosu, Madalin-Mihai
2015-01-01
The CERN Axion Solar Telescope (CAST) is an experiment that uses the world’s highest sensitivity Helioscope to date for solar Axions searches. Axions are weakly interacting pseudoscalar particles proposed to solve the so-called Strong Charge-Parity Problem of the Standard Model. The principle of detection is the inverse Primakoff Effect, which is a mechanism for converting the Axions into easily detectable X-ray photons in a strong transverse magnetic field. The solar Axions are produced d...
Mixed axion/neutralino dark matter in the SUSY DFSZ axion model
Bae, Kyu Jung; Chun, Eung Jin
2013-01-01
We examine mixed axion/neutralino cold dark matter production in the SUSY DFSZ axion model where an axion superfield couples to Higgs superfields. We calculate a wide array of axino and saxion decay modes along with their decay temperatures, and thermal and non-thermal production rates. For a SUSY benchmark model with a standard underabundance (SUA) of Higgsino-like dark matter (DM), we find for the PQ scale f_a~ 10^{14} GeV, both neutralino dark matter and dark radiation are typically overproduced. For judicious parameter choices, these can be suppressed and the combined neutralino/axion abundance brought into accord with measured values. A SUSY benchmark model with a standard overabundance (SOA) of bino DM is also examined and typically remains excluded due at least to too great a neutralino DM abundance for f_a~ 10^{15} GeV and lower saxion masses, large entropy production from saxion decay can dilute all relics and the SOA model can be allowed by all constraints.
A New Target for Cosmic Axion Searches
Baumann, Daniel; Wallisch, Benjamin
2016-01-01
Future CMB experiments have the potential to probe the density of relativistic species at the sub-percent level. Sensitivity at this level allows light thermal relics to be detected up to arbitrarily high decoupling temperatures. Conversely, the absence of a detection would require extra light species never to have been in equilibrium with the Standard Model. In this paper, we exploit this feature to demonstrate the sensitivity of future cosmological observations to the couplings of axions to all of the Standard Model degrees of freedom. In many cases, the constraints achievable from cosmology will surpass existing bounds from laboratory experiments and astrophysical observations by orders of magnitude.
Electric and magnetic energy at axion haloscopes
Ko, B R; Jang, W; Choi, J; Kim, D; Lee, M J; Lee, J; Won, E; Semertzidis, Y K
2016-01-01
We review a recent letter published in Phys. Rev. Lett. $\\textbf{116}$, 161804 (2016) of which the main argument is that the mode dependent magnetic form factors at axion haloscopes depend on the position of the cavity inside the solenoid while the corresponding electric form factors do not. We, however, find no such dependence, which is also equivalent to the statement that the electric and corresponding magnetic energy stored in the cavity modes are the same regardless of the position of the cavity inside the solenoid. Furthermore, we extend the statement to the cases satisfying $\\vec{\
Solitonic axion condensates modeling dark matter halos
Castañeda Valle, David; Mielke, Eckehard W.
2013-09-01
Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose-Einstein type condensates could provide a viable soliton type interpretation of the DM 'bullets' observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein-Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two 'lump' type solitons.
CAST constraints on the axion-electron coupling
Barth, K.; Davenport, M.; Lella, L. Di [European Organization for Nuclear Research (CERN), Geneve (Switzerland); Belov, A. [Institute for Nuclear Research (INR), Russian Academy of Sciences, Moscow (Russian Federation); Beltran, B.; Carmona, J.M.; Dafni, T.; Galan, J.; García, J.A. [Laboratorio de Fisica Nuclear y Altas Energias, Universidad de Zaragoza, Zaragoza (Spain); Braeuninger, H.; Englhauser, J.; Friedrich, P. [Max-Planck-Institut fuer extraterrestrische Physik, Garching (Germany); Collar, J.I. [Enrico Fermi Institute and KICP, University of Chicago, Chicago, IL (United States); Eleftheriadis, C. [Aristoteles University of Thessaloniki, Thessaloniki (Greece); Fanourakis, G.; Geralis, T. [National Center for Scientific Research ' ' Demokritos' ' , Athens (Greece); Ferrer-Ribas, E.; Giomataris, I. [IRFU, Centre d' Etudes Nucleaires de Saclay (CEA-Saclay), Gif-sur-Yvette (France); Fischer, H.; Franz, J., E-mail: Jaime.Ruz@cern.ch, E-mail: Julia.Vogel@cern.ch, E-mail: redondo@mpp.mpg.de [Albert-Ludwigs-Universitaet Freiburg, Freiburg (Germany); and others
2013-05-01
In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces a strong axion flux by bremsstrahlung, Compton scattering, and axio-recombination, the ''BCA processes.'' Based on a new calculation of this flux, including for the first time axio-recombination, we derive limits on the axion-electron Yukawa coupling g{sub ae} and axion-photon interaction strength g{sub aγ} using the CAST phase-I data (vacuum phase). For m{sub a}∼<10 meV/c{sup 2} we find g{sub aγ} g{sub ae} < 8.1 × 10{sup −23} GeV{sup −1} at 95% CL. We stress that a next-generation axion helioscope such as the proposed IAXO could push this sensitivity into a range beyond stellar energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission.
Design for a practical laboratory detector for solar axions
We present a practical design for a detector sensitive to axions and other light particles with a two-photon interaction vertex. Such particles would be produced in the solar interior by Primakoff conversion of blackbody photons and could be detected by their reconversion into x rays (average energy about 4 keV) in a strong laboratory magnetic field. An existing large superconducting magnet would be suitable for this purpose. The transition rate is enhanced by filling the conversion region with a buffer gas (H2 or He). This induces an effective photon mass (plasma frequency) which can be adjusted to equal the axion mass being searched for. Axion-photon conversion is then coherent throughout the detector volume for all axion energies. Axions with mass in the range 0.1 eVapprox. < m/sub a/approx. <5 eV can be detected using gas pressures of 0.1--300 atm. Axions with the standard coupling strength to photons would give counting rates of 10/sup -5/--10 sec/sup -1/ over this mass range. The search would definitively test one of the only two regions of axion parameters not excluded by astrophysical constraints
Search for Solar Axions with the CAST-Experiment
Vogel, J.; Aune, S.; Autiero, D.; Barth, K.; Belov, A.; Beltran, B.; Borghi, S.; Bourlis, G.; Boydag, F. S.; Brauninger, H.; Carmona, J.; Cebrian, S.; Cetin, S. A.; Collar, J.I.; Dafni, T.; Davenport, M.; Di Lella, L.; Dogan, O. B.; Elefheriadis, C.; Elias, N.; Fanourakis, G.; Ferrer-Ribas, E.; Fisher, H.; Franz, J.; Galan, J.; Geralis, T.; Giomataris, I.; Gninenko, S.; Gomez, H.; Hasinoff, M.; Heinsius, H.; Hikmet, I.; Hoffmann, D. H. H.; Irastorza, I. G.; Jacoby, J.; Jakovcic, K.; Kang, D.; Konigsmann, K.; Kotthaus, R.; Krcmar, M.; Kousouris, K.; Kuster, M.; Lakic, B.; Lasseur, C.; Liolios, A.; Ljubicic, A.; Lutz, G.; Luzon, G.; Miller, D.; Morales, J.; Niinikoski, T.; Nordt, A.; Ortiz, A.; Papaevangelou, T.; Pivovaroff, M.; Placci, A.; Raffelt, G.; Riege, H.; Rodriguez, A.; Ruz, J.; Savvidis, I.; Semertzidis, Y.; Serpico, P.; Soufli, R.; Stewart, L.; Tzamarias, S.; Van Bibber, K.; Villar, J.; Walckiers, L.; Zioutas, K.; Morales, A.
2008-01-01
Solar axions can be produced in the Sun via the so-called Primakoff effect. The CERN Axion Solar Telescope (CAST) uses an LHC prototype magnet of about 9 T to reconvert these axions into photons. The magnet is able to follow the Sun for about 3 hours per day. Three different X-Ray detectors are mounted on its ends to detect photons from axion-to-photon conversion: a Time Projection Chamber (TPC), a MICROMEGAS (MICROMEsh GAseous Structure) and a Charge Coupled Device (CCD). For the CCD an X-ray focusing device is used to improve the signal-to-background ratio significantly. With the completion of CAST'S first phase, the current limits on the coupling constant gaγ for axion masses up to 0.02 eV have been improved. In its second phase, CAST extends the axion mass range by filling the magnet with a buffer gas. Masses up to about 0.4 eV have already been covered and thus the experiment is entering the regions favored by axion models. This paper will present the status of CAST'S second phase.
Hardimon, Michael O
2013-02-01
Confusions about the place of race in medicine result in part from a failure to recognize the plurality of race concepts. Recognition that the ordinary concept of race is not identical to the racialist concept of race makes it possible to ask whether there might be a legitimate place for the deployment of concepts of race in medical contexts. Two technical race concepts are considered. The concept of social race is the concept of a social group that is taken to be a racialist race. It is apt for use in examining and addressing the medical effects of discrimination. The populationist concept of race represents race as a kind of biological population. It makes it possible to frame the question whether biological race is a factor in disease susceptibility and drug responsiveness. It is apt for use in determining whether biological race is a medically significant category. PMID:23300217
Dilution of axion dark radiation by thermal inflation
Hattori, Hironori; Omoto, Naoya; Seto, Osamu
2015-01-01
Axion in the Peccei-Quinn (PQ) mechanism provides a promising solution to the strong CP problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would confront with the current dark radiation constraints. We study the possibility that a thermal inflation driven by a $U(1)$ gauged Higgs field dilutes such axions. A well motivated extra gauged $U(1)$ would be the local $B-L$ symmetry. We also discuss the implication for the case of $U(1)_{B-L}$ and available baryogenesis mechanism in such cosmology.
Searching for galactic axions through magnetized media: the QUAX proposal
Barbieri, R.; Braggio, C.; Carugno, G.; Gallo, C. S.; Lombardi, A; Ortolan, A.; Pengo, R.; Ruoso, G.; Speake, C. C.
2016-01-01
We present a proposal to search for QCD axions with mass in the 100 $\\mu$eV range, assuming that they make a dominant component of dark matter. Due to the axion-electron spin coupling, their effect is equivalent to the application of an oscillating rf field with frequency and amplitude fixed by the axion mass and coupling respectively. This equivalent magnetic field would produce spin flips in a magnetic sample placed inside a static magnetic field, which determines the resonant interaction a...
Constraining Axion Dark Matter with Big Bang Nucleosynthesis
Kfir Blum; Raffaele Tito D'Agnolo; Mariangela Lisanti; Benjamin R. Safdi
2014-01-01
We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD $\\theta$ angle that redshifts in the early universe, increasing the neutron-proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for time-varying ...
Active galaxies may harbour wormholes if dark matter is axionic
Dimopoulos, Konstantinos
2016-01-01
AGN jets carry helical magnetic fields, which can affect dark matter if the latter is axionic. This preliminary study shows that the nature of the axionic condensate may change and instead of dark matter may behave more like exotic matter, which violates the null energy condition. If the central supermassive black hole of an active galaxy is laced with exotic matter then it may become a wormhole. In general, the presence of exotic matter may affect galaxy formation and galactic dynamics, so this possibility should not be ignored when considering axionic dark matter.
Suppressing the QCD axion abundance by hidden monopoles
Kawasaki, Masahiro [Tokyo Univ., Chiba (Japan). Inst. for Cosmic Ray Research; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; Takahashi, Fuminobu [Tokyo Univ., Miyagi (Japan). Dept. of Physics; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; Yamada, Masaki [Tokyo Univ., Chiba (Japan). Inst. for Cosmic Ray Research; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; DESY Hamburg (Germany)
2015-11-15
We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than 10{sup 12} GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei-Quinn symmetry is spontaneously broken after inflation.
Axion cyclotron emissivity of magnetized white dwarfs and neutron stars
Kachelriess, M.; Wilke, C.; Wunner, G.
1997-01-01
The energy loss rate of a magnetized electron gas emitting axions a due to the process $e^- \\to e^- +a$ is derived for arbitrary magnetic field strength B. Requiring that for a strongly magnetized neutron star the axion luminosity is smaller than the neutrino luminosity we obtain the bound $g_{ae}\\lsim 10^{-10}$ for the axion electron coupling constant. This limit is considerably weaker than the bound derived earlier by Borisov and Grishina using the same method. Applying a similar argument t...
Axion Emission from Red Giants and White Dwarfs
Altherr, Tanguy; Gaztelurrutia, T R
1994-01-01
Using thermal field theory methods, we recalculate axion emission from dense plasmas. We study in particular the Primakoff and the bremsstrahlung processes. The Primakoff rate is significantly suppressed at high densities, when the electrons become relativistic. However, the bound on the axion-photon coupling, $G<10^{-10}$ GeV, is unaffected, as it is constrained by the evolution of HB stars, which have low densities. In contradistinction, the same relativistic effects enhance the bremsstrahlung processes. From the red giants and white dwarfs evolution, we obtain a conservative bound on the axion-electron coupling, $g_{ae} < 2\\times 10^{-13}$.
Accelerating dark-matter axion searches with quantum measurement technology
Zheng, Huaixiu; Brierley, R T; Girvin, S M; Lehnert, K W
2016-01-01
The axion particle, a consequence of an elegant hypothesis that resolves the strong-CP problem of quantum chromodynamics, is a plausible origin for cosmological dark matter. In searches for axionic dark matter that detect the conversion of axions to microwave photons, the quantum noise associated with microwave vacuum fluctuations will soon limit the rate at which parameter space is searched. Here we show that this noise can be partially overcome either by squeezing the quantum vacuum using recently developed Josephson parametric devices, or by using superconducting qubits to count microwave photons.
The cern axion solar telescope (CAST): an update
Andriamonje, S.; Arsov, V.; Aune, S.; Aune, T.; Avignone, F. T.; Barth, K.; Belov, A.; Beltran, B.; Bräuninger, H.; Carmona, J.; Cebrián, S.; Chesi, E.; Cipolla, G.; Collar, J.; Creswick, R.; Dafni, T.; Davenport, M.; Dedousis, S.; Delattre, M.; Delbart, A.; Deoliveira, R.; Dilella, L.; Eleftheriadis, C.; Engelhauser, J.; Fanourakis, G.; Farach, H.; Ferrer, E.; Fischer, H.; Formenti, F.; Franz, J.; Friedrich, P.; Geralis, T.; Giomataris, I.; Gninenko, S.; Golubev, N.; Hartmann, R.; Hasinoff, M.; Heinsius, F.-H.; Hoffmann, D. H. H.; Irastorza, I.; Jacoby, J.; Joux, J.-N.; Kang, D.; Königsmann, K.; Kotthaus, R.; Krcmar, M.; Kuster, M.; Lakic, B.; Lasseur, C.; Liolios, A.; Lippitsch, A.; Ljubicic, A.; Lutz, G.; Luzon, G.; Morales, A.; Morales, J.; Mutterer, M.; Nikolaidis, A.; de Solorzano, A. Ortiz; Papaevangelou, T.; Placci, A.; Raffelt, G.; Rammos, P.; Robert, J. P.; Ruz, J.; Sarsa, M.; Schill, C.; Serber, W.; Semertzidis, Y.; Vieira, J.; Villar, J.; Vullierme, B.; Walckiers, L.; Zioutas, K.
2005-01-01
The CERN Axion Solar Telescope (CAST), a 10 meter long LHC, 9 Tesla, test magnet is mounted on a moving platform that tracks the sun about 1.5 hours during sunrise, again during sunset. It moves ±80 vertically and ±400 horizontally. It has been taking data continuously since July 10, 2003. Data analyzed thus far yield an upper bound on the photon-axion coupling constant, gaγγ ⩽ 3 × 10-10 GeV-1 for axion masses less than 5 × 10-2 eV.
The CERN axion solar telescope (CAST): an update
The CERN Axion Solar Telescope (CAST), a 10 meter long LHC, 9 Tesla, test magnet is mounted on a moving platform that tracks the sun about 1.5 hours during sunrise, again during sunset. It moves ±80 vertically and ±400 horizontally. It has been taking data continuously since July 10, 2003. Data analyzed thus far yield an upper bound on the photon-axion coupling constant, g aγγ 3 x 10-10 GeV-1 for axion masses less than 5 x 10-2 eV
An argument that the dark matter is axions
Sikivie, P.
2012-01-01
An argument is presented that the dark matter is axions, at least in part. It has three steps. First, axions behave differently from the other forms of cold dark matter because they form a rethermalizing Bose-Einstein condensate (BEC). Second, there is a tool to distinguish axion BEC from the other dark matter candidates on the basis of observation, namely the study of the inner caustics of galactic halos. Third, the observational evidence for caustic rings of dark matter is consistent in eve...
Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas.
Arik, M; Aune, S; Barth, K; Belov, A; Borghi, S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Eleftheriadis, C; Elias, N; Ezer, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Gazis, E N; Geralis, T; Giomataris, I; Gninenko, S; Gómez, H; Gruber, E; Guthörl, T; Hartmann, R; Haug, F; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakovčić, K; Karuza, M; Königsmann, K; Kotthaus, R; Krčmar, M; Kuster, M; Lakić, B; Laurent, J M; Liolios, A; Ljubičić, A; Lozza, V; Lutz, G; Luzón, G; Morales, J; Niinikoski, T; Nordt, A; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Rashba, T; Riege, H; Rodríguez, A; Rosu, M; Ruz, J; Savvidis, I; Silva, P S; Solanki, S K; Stewart, L; Tomás, A; Tsagri, M; van Bibber, K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K
2011-12-23
The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV≲m(a)≲0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)≲2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)≲1.15 eV, comfortably overlapping with cosmological hot dark matter bounds. PMID:22243149
D6-branes and axion monodromy inflation
Escobar, Dagoberto; Marchesano, Fernando; Regalado, Diego
2015-01-01
We develop new scenarios of large field inflation in type IIA string compactifications in which the key ingredient is a D6-brane that creates a potential for a B-field axion. The potential has the multi-branched structure typical of F-term axion monodromy models and, near its supersymmetric minima, it is described by a 4d supergravity model of chaotic inflation with a stabiliser field. The same statement applies to the D6-brane Wilson line, which can also be considered as an inflaton candidate. We analyse both cases in the context of type IIA moduli stabilisation, finding an effective potential for the inflaton system and a simple mechanism to lower the inflaton mass with respect to closed string moduli stabilised by fluxes. Finally, we compute the B-field potential for trans-Planckian field values by means of the DBI action. The effect of Planck suppressed corrections is a flattened potential which, in terms of the compactification parameters, interpolates between linear and quadratic inflation. This renders...
Axion dark matter from topological defects
Kawasaki, Masahiro; Sekiguchi, Toyokazu
2014-01-01
The cosmological scenario where the Peccei-Quinn symmetry is broken after inflation is investigated. In this scenario, topological defects such as strings and domain walls produce a large amount of axions, which contribute to the cold dark matter of the universe. The previous estimations of the cold dark matter abundance are updated and refined based on the field-theoretic simulations with improved grid sizes. The possible uncertainties originated in the numerical calculations are also discussed. It is found that axions can be responsible for the cold dark matter in the mass range $m_a=(0.9$-$1.4)\\times 10^{-4}\\mathrm{eV}$ for the models with the domain wall number $N_{\\rm DW}=1$, and $m_a\\approx\\mathcal{O}(10^{-4}$-$10^{-2})\\mathrm{eV}$ with a mild tuning of parameters for the models with $N_{\\rm DW}>1$. Such higher mass ranges can be probed in the future experimental studies.
Non-gaussianity from axion monodromy inflation
Hannestad, Steen; Haugbolle, Troels; Jarnhus, Philip R. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Sloth, Martin S., E-mail: sth@phys.au.dk, E-mail: haugboel@nbi.ku.dk, E-mail: pjarn@phys.au.dk, E-mail: martin.sloth@cern.ch [CERN, Physics Department, Theory Unit, CH-1211 Geneva 23 (Switzerland)
2010-06-01
We study the primordial non-Gaussianity predicted from simple models of inflation with a linear potential and superimposed oscillations. This generic form of the potential is predicted by the axion monodromy inflation model, that has recently been proposed as a possible realisation of chaotic inflation in string theory, where the monodromy from wrapped branes extends the range of the closed string axions to beyond the Planck scale. The superimposed oscillations in the potential can lead to new signatures in the CMB spectrum and bispectrum. In particular the bispectrum will have a new distinct shape. We calculate the power spectrum and bispectrum of curvature perturbations in the model, as well as make analytic estimates in various limiting cases. From the numerical analysis we find that for a wide range of allowed parameters the model produces a feature in the bispectrum with f{sub NL} ∼ 5−50 or larger while the power spectrum is almost featureless. This model is therefore an example of a string inspired inflationary model which is testable mainly through its non-Gaussian features. Finally we provide a simple analytic fitting formula for the bispectrum which is accurate to approximately 5 % in all cases, and easily implementable in codes designed to provide non-Gaussian templates for CMB analyses.
Non-gaussianity from axion monodromy inflation
We study the primordial non-Gaussianity predicted from simple models of inflation with a linear potential and superimposed oscillations. This generic form of the potential is predicted by the axion monodromy inflation model, that has recently been proposed as a possible realisation of chaotic inflation in string theory, where the monodromy from wrapped branes extends the range of the closed string axions to beyond the Planck scale. The superimposed oscillations in the potential can lead to new signatures in the CMB spectrum and bispectrum. In particular the bispectrum will have a new distinct shape. We calculate the power spectrum and bispectrum of curvature perturbations in the model, as well as make analytic estimates in various limiting cases. From the numerical analysis we find that for a wide range of allowed parameters the model produces a feature in the bispectrum with fNL ∼ 5−50 or larger while the power spectrum is almost featureless. This model is therefore an example of a string inspired inflationary model which is testable mainly through its non-Gaussian features. Finally we provide a simple analytic fitting formula for the bispectrum which is accurate to approximately 5 % in all cases, and easily implementable in codes designed to provide non-Gaussian templates for CMB analyses
Vacuum statistics and stability in axionic landscapes
Masoumi, Ali; Vilenkin, Alexander
2016-03-01
We investigate vacuum statistics and stability in random axionic landscapes. For this purpose we developed an algorithm for a quick evaluation of the tunneling action, which in most cases is accurate within 10%. We find that stability of a vacuum is strongly correlated with its energy density, with lifetime rapidly growing as the energy density is decreased. On the other hand, the probability P(B) for a vacuum to have a tunneling action B greater than a given value declines as a slow power law in B. This is in sharp contrast with the studies of random quartic potentials, which found a fast exponential decline of P(B). Our results suggest that the total number of relatively stable vacua (say, with B>100) grows exponentially with the number of fields N and can get extremely large for Ngtrsim 100. The problem with this kind of model is that the stable vacua are concentrated near the absolute minimum of the potential, so the observed value of the cosmological constant cannot be explained without fine-tuning. To address this difficulty, we consider a modification of the model, where the axions acquire a quadratic mass term, due to their mixing with 4-form fields. This results in a larger landscape with a much broader distribution of vacuum energies. The number of relatively stable vacua in such models can still be extremely large.
Race and Gender Issues: Critical Race Feminism.
Wing, Adrien K.
1999-01-01
Introduces a new body of legal scholarship on race and gender: critical race feminism (CRF), examining critical legal studies, critical race theory, and feminism. Explains the term "global multiplicative identities" as it relates to CRF and concludes that CRF has the potential to benefit from more sustained interaction with human rights workers in…