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J I Collar - One of the best experts on this subject based on the ideXlab platform.
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search for solar Axions by the cern Axion solar telescope with 3he buffer gas closing the hot dark matter gap
Physical Review Letters, 2014Co-Authors: M Arik, S Aune, K Barth, A Belov, S Borghi, H Brauninger, G Cantatore, J M Carmona, S A Cetin, J I CollarAbstract:The CERN Axion Solar Telescope has finished its search for solar Axions with He-3 buffer gas, covering the search range 0.64 eV less than or similar to ma less than or similar to 1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. 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(a gamma) less than or similar to 3.3 x 10(-10) GeV-1 at 95% C.L., with the exact value depending on the pressure setting. Future direct solar Axion searches will focus on increasing the sensitivity to smaller values of g(a gamma), for example by the currently discussed next generation helioscope International Axion Observatory.
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search for sub ev mass solar Axions by the cern Axion solar telescope with 3he buffer gas
Physical Review Letters, 2011Co-Authors: M Arik, S Aune, K Barth, A Belov, S Borghi, H Brauninger, G Cantatore, J M Carmona, S A Cetin, J I CollarAbstract: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.
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an improved limit on the Axion photon coupling from the cast experiment
Journal of Cosmology and Astroparticle Physics, 2007Co-Authors: S Andriamonje, S Aune, K Barth, A Belov, H Brauninger, J M Carmona, D Autiero, B Beltran, S Cebrian, J I CollarAbstract:We have searched for solar Axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) set-up with improved conditions in all detectors. From the absence of excess x-rays when the magnet was pointing to the Sun, we set an upper limit on the Axion–photon coupling of gaγ<8.8 × 10−11 GeV−1 at 95% CL for . This result is the best experimental limit over a broad range of Axion masses and for also supersedes the previous limit derived from energy-loss arguments on globular cluster stars.
Sacha Davidson - One of the best experts on this subject based on the ideXlab platform.
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Axion absorption and the spin temperature of primordial hydrogen
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Adrien Auriol, Sacha Davidson, Georg G RaffeltAbstract:An absorption dip in the spectrum of the cosmic microwave background observed by the EDGES experiment suggests an unexplained reduction of the hydrogen spin temperature at cosmic redshift z ~ 17. The mass of dark-matter Axions could correspond to the hyperfine splitting of 5.9 micro-eV, between the triplet (H1) and singlet (H0) state. We calculate the rate for a+ H0 H1 in two ways, and find that it is orders of magnitude smaller than the CMB-mediated transition rate, so irrelevant. As a result, this process cannot be used to rule in or out dark matter Axions of mass = hyperfine splitting. The Axion rate nonetheless has interesting features, for example, on balance it heats the spin temperature, and the Axion couplings to protons and electrons contribute on equal footing.
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Axions bose einstein condensate or classical field
Astroparticle Physics, 2015Co-Authors: Sacha DavidsonAbstract:Abstract The Axion is a motivated dark matter candidate, so it would be interesting to find features in Large Scale Structures specific to Axion dark matter. Such features were proposed for a Bose Einstein condensate of Axions, leading to confusion in the literature (to which I contributed) about whether Axions condense due to their gravitational interactions. This note argues that the Bose Einstein condensation of Axions is a red herring: the Axion dark matter produced by the misalignment mechanism is already a classical field, which has the distinctive features attributed to the Axion condensate (BE condensates are described as classical fields). This note also estimates that the rate at which Axion particles condense to the field, or the field evaporates to particles, is negligible.
P Sikivie - One of the best experts on this subject based on the ideXlab platform.
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production and detection of an Axion dark matter echo
Physical Review Letters, 2019Co-Authors: Ariel Arza, P SikivieAbstract:Electromagnetic radiation with angular frequency equal to half the Axion mass stimulates the decay of cold dark matter Axions and produces an echo, i.e., faint electromagnetic radiation traveling in the opposite direction. We propose to search for Axion dark matter by sending out to space a powerful beam of microwave radiation and listening for its echo. We estimate the sensitivity of this technique in the isothermal and caustic ring models of the Milky Way halo and find it to be a promising approach to Axion, or Axionlike, dark matter detection.
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Axions and the galactic angular momentum distribution
Physical Review D, 2013Co-Authors: Nilanjan Banik, P SikivieAbstract:We analyze the behavior of Axion dark matter before it falls into a galactic gravitational potential well. The Axions thermalize sufficiently fast by gravitational self-interactions that almost all go to their lowest energy state consistent with the total angular momentum acquired from tidal torquing. That state is a state of rigid rotation on the turnaround sphere. It predicts the occurrence and detailed properties of the caustic rings of dark matter for which observational evidence had been found earlier. We show that the vortices in the Axion Bose-Einstein condensate (BEC) are attractive, unlike those in superfluid $^4$He and dilute gases. We expect that a large fraction of the vortices in the Axion BEC join into a single big vortex along the rotation axis of the galaxy. The resulting enhancement of caustic rings explains the typical size of the rises in the Milky Way rotation curve attributed to caustic rings. We show that baryons and ordinary cold dark matter particles are entrained by the Axion BEC and acquire the same velocity distribution. The resulting baryonic angular momentum distribution gives a good qualitative fit to the distributions observed in dwarf galaxies. We give estimates of the minimum fraction of dark matter that is Axions.
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Bose-einstein condensation of dark matter Axions
Physical Review Letters, 2009Co-Authors: P SikivieAbstract:We show that cold dark matter Axions thermalize and form a Bose-Einstein condensate (BEC). 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 nonlinear 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 microwave anisotropy multipoles.
Kyu Jung Bae - One of the best experts on this subject based on the ideXlab platform.
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light axinos from freeze in production processes phase space distributions and ly α forest constraints
Journal of Cosmology and Astroparticle Physics, 2018Co-Authors: Kyu Jung Bae, Ayuki Kamada, Seng Pei Liew, Keisuke YanagiAbstract:We consider the freeze-in production of 7 keV axino dark matter (DM) in the supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model in light of the 3.5 keV line excess. The warmness of such 7 keV DM produced from the thermal bath, in general, appears in tension with Ly-α forest data, although a direct comparison is not straightforward. This is because the Ly-α forest constraints are usually reported on the mass of the conventional warm dark matter (WDM), where large entropy production is implicitly assumed to occur in the thermal bath after WDM particles are decoupled. The phase space distribution of freeze-in axino DM varies depending on production processes and axino DM may alleviate the tension with the tight Ly-α forest constraints. By solving the Boltzmann equation, we first obtain the resultant phase space distribution of axinos produced by 2-body decay, 3-body decay, and 2-to-2 scattering respectively. The reduced collision term and resultant phase space distribution are useful for studying other freeze-in scenarios as well. We then calculate the resultant linear matter power spectra for such axino DM and directly compare them with the linear matter power spectra for the conventional WDM . In order to demonstrate realistic axino DM production, we consider benchmark points with Higgsino next-to-light supersymmetric particle (NLSP) and wino NLSP. In the case of Higgsino NLSP, the phase space distribution of axinos is colder than that in the conventional WDM case, so the most stringent Ly-α forest constraint can be evaded with mild entropy production from sAxion decay inherent in the supersymmetric DFSZ Axion model.
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coupled boltzmann computation of mixed Axion neutralino dark matter in the susy dfsz Axion model
Journal of Cosmology and Astroparticle Physics, 2014Co-Authors: Kyu Jung Bae, Howard Baer, Andre Lessa, Hasan SerceAbstract: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 ?-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 (?=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 (??=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.
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coupled boltzmann computation of mixed Axion neutralino dark matter in the susy dfsz Axion model
arXiv: High Energy Physics - Phenomenology, 2014Co-Authors: Kyu Jung Bae, Howard Baer, Andre Lessa, Hasan SerceAbstract: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 the SUA case with suppressed sAxion-Axion couplings (\xi=0) only admits solutions for PQ breaking scale f_a~< 5\times 10^{12} GeV where the bulk of parameter space tends to be Axion-dominated. For SUA with allowed sAxion-Axion couplings (\xi =1), then f_a values up to ~ 2\times 10^{14} 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 f_a~ 10^{15}-10^{16} GeV where large entropy dilution from CO-produced sAxions leads to allowed models.
K Van Bibber - One of the best experts on this subject based on the ideXlab platform.
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haystac Axion search analysis procedure
Physical Review D, 2017Co-Authors: B M Brubaker, L Zhong, S K Lamoreaux, K W Lehnert, K Van BibberAbstract:We describe in detail the analysis procedure used to derive the first limits from the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a microwave cavity search for cold dark matter (CDM) Axions with masses above $20\ \mu\text{eV}$. We have introduced several significant innovations to the Axion search analysis pioneered by the Axion Dark Matter eXperiment (ADMX), including optimal filtering of the individual power spectra that constitute the Axion search dataset and a consistent maximum likelihood procedure for combining and rebinning these spectra. These innovations enable us to obtain the Axion-photon coupling $|g_\gamma|$ excluded at any desired confidence level directly from the statistics of the combined data.
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haystac Axion search analysis procedure
Physical Review D, 2017Co-Authors: B M Brubaker, L Zhong, S K Lamoreaux, K W Lehnert, K Van BibberAbstract:We describe in detail the analysis procedure used to derive the first limits from the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a microwave cavity search for cold dark matter (CDM) Axions with masses above $20\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. We have introduced several significant innovations to the Axion search analysis pioneered by the Axion Dark Matter eXperiment (ADMX), including optimal filtering of the individual power spectra that constitute the Axion search data set and a consistent maximum likelihood procedure for combining and rebinning these spectra. These innovations enable us to obtain the Axion-photon coupling $|{g}_{\ensuremath{\gamma}}|$ excluded at any desired confidence level directly from the statistics of the combined data.
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the international Axion observatory iaxo letter of intent to the cern sps committee
2013Co-Authors: I G Irastorza, K Van Bibber, F T Avignone, A Liolios, S Russenschuck, T Geralis, O Limousin, J A Villar, H Gomez, Joerg JaeckelAbstract:This Letter of Intent describes IAXO, the International Axion Observatory, a proposed 4th 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 background ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, which means that this instrument will reach sensitivity to Axion-photon couplings down to a few ×10−12 GeV−1. IAXO has the potential for the discovery of Axions and other ALPs, since it will deeply enter into unexplored parameter space. At the very least it will firmly exclude a large region of this space of high cosmological and astrophysical relevance. In particular it will probe a large fraction of the high mass part (1 meV to 1 eV) of the QCD Axion allowed window. Additional physics cases for IAXO include the possibility of detecting 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. IAXO follows the conceptual layout of an enhanced Axion helioscope, with a purpose-built 8-coils toroidal superconducting magnet. All the eight 60-cm 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 the will allow for solar tracking for ∼12 h each day. All the enabling technologies exists, there is no need for development. All the needed know-how is present in the proponent groups. Potential additional physics cases for IAXO to be developed in the future are the search of Axionic dark radiation, relic cold dark matter Axions or the realization of microwave light-shining-through wall setups, as well as the search of more specific models of weakly interacting sub-eV particles (WISPs) at the low energy frontier of particle physics. IAXO has the potential to serve as a multi-purpose facility for generic Axion and ALP research in the next decade.
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squid based microwave cavity search for dark matter Axions
Physical Review Letters, 2010Co-Authors: S J Asztalos, K Van Bibber, M Hotz, G Carosi, C Hagmann, D Kinion, L J Rosenberg, G Rybka, J Hoskins, Jungseek HwangAbstract:Axions in the $\ensuremath{\mu}\mathrm{eV}$ mass range are a plausible cold dark-matter candidate and may be detected by their conversion into microwave photons in a resonant cavity immersed in a static magnetic field. We report the first result from such an Axion search using a superconducting first-stage amplifier (SQUID) replacing a conventional GaAs field-effect transistor amplifier. This experiment excludes KSVZ dark-matter Axions with masses between $3.3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ and $3.53\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ and sets the stage for a definitive Axion search utilizing near quantum-limited SQUID amplifiers.
