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Sample records for ilias-cast-cern axion training

  1. Axion cosmology

    NASA Astrophysics Data System (ADS)

    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

  2. Axions and SN 1987A: Axion trapping

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Ressell, M. Ted; Turner, Michael S.

    1990-01-01

    If an axion of mass between about 10(exp -3) and 10 eV exists, axion emission would have significantly affected the cooling of the nascent neutron star associated with SN 1987A. For an axion of mass greater than about 10(exp -2) eV axions would, like neutrinos, have a mean-free path that is smaller than the size of a neutron star, and thus would become trapped and radiated from an axion sphere. The trapping regime is treated by using numerical models of the initial cooling of a hot neutron star that incorporate a diffusion approximation for axion-energy transport. The axion opacity due to inverse nucleon-nucleon, axion bremsstrahlung is computed; and then the numerical models are used to calculate the integrated axion luminosity, the temperature of the axion sphere, and the effect of axion emission on the neutrino bursts detected by the Kamiokande II (KII) and Irvine-Michigan-Brookhaven (IMB) water-Cherenkov detectors. The larger the axion mass, the stronger the trapping and the smaller the axion luminosity. The estimate of the axion mass is confirmed above which trapping is so strong that axion emission does not significantly affect the neutrino burst. Based upon the neutrino-burst duration - the most sensitive barometer of axion cooling - it is concluded that for an axion mass greater than about 3 eV axion emission would not have had a significant effect on the neutrino bursts detected by KII and IMB. It is strongly suggested that an axion with mass in the interval 10(exp -3) to 3 eV is excluded by the observation of neutrinos from SN 1987A.

  3. Axions and SN 1987A: Axion trapping

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Ressell, M. Ted; Turner, Michael S.

    1990-01-01

    If an axion of mass between about 10(exp -3) eV and 1 eV exists, axion emission would have significantly affected the cooling of the nascent neutron star associated with SN 1987A. For an axion of mass less than about 10(exp -2) eV, axions produced deep inside the neutron star simply stream out; in a previous paper this case has been addressed. Remarkably, for an axion of mass greater than about 10(exp -2) eV axions would, like neutrinos, have a mean-free path that is smaller than the size of a neutron star, and thus would become 'trapped' and radiated from an axion sphere. In this paper the trapping regime is treated by using numerical models of the initial cooling of a hot neutron star that incorporate a leakage approximation scheme for axion-energy transport. The axion opacity is computed due to inverse nucleon-nucleon, axion bremsstrahlung, and numerical models are used to calculate the integrated axion luminosity, the temperature of the axion sphere, and the effect of axion emission on the neutrino bursts detected by the Kamiokande 2 (K2) and Irvine-Michigan-Brookhaven (IMB) water-Cherenkov detectors. The larger the axion mass, the stronger the trapping and the smaller the axion luminosity. The earlier estimate is confirmed and refined of the axion mass above which trapping is so strong that axion emission does not significantly affect the neutrino burst. Based upon the neutrino-burst duration--the most sensitive barometer of axion cooling--it is concluded that for an axion mass of greater than about 0.3 eV, axion emission would not have had a significant effect on the neutrino bursts detected by K2 and IMB. The present work, together with the previous work, strongly suggests that an axion with mass in the interval 10(exp -3) eV to 0.3 eV is excluded by SN 1987A.

  4. Experimental probes of axions

    SciTech Connect

    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.

  5. Dark matter axions

    SciTech Connect

    Sikivie, P. |

    1992-09-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  6. Dark matter axions

    SciTech Connect

    Sikivie, P. . Inst. for Theoretical Physics Florida Univ., Gainesville, FL . Dept. of Physics)

    1992-01-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  7. Axions from string decay

    SciTech Connect

    Hagmann, C., LLNL

    1998-07-09

    We have studied numerically the evolution and decay of axion strings. These global defects decay mainly by axion emission and thus contribute to the cosmological axion energy density. The relative importance of this source relative to misalignment production of axions depends on the spectrum. Radiation spectra for various string loop configurations are presented. They support the contention that the string decay contribution is of the same order of magnitude as the contribution from misalignment.

  8. Inflationary axion cosmology

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Wilczek, Frank

    1991-01-01

    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 to the -6th 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. Consideration of fluctuations induced during inflation severely constrains the latter alternative is shown.

  9. Inflationary Axion Cosmology

    DOE R&D Accomplishments Database

    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.

  10. (Mainly) axion dark matter

    NASA Astrophysics Data System (ADS)

    Baer, Howard

    2016-06-01

    The strong CP problem of QCD is at heart a problem of naturalness: why is the FF ˜ 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 fa ˜ 1011 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 dark matter. Ultimately we would expect detection of both an axion and a WIMP while signals for light higgsinos may show up at LHC and must show up at ILC.

  11. Axion dark matter searches

    SciTech Connect

    Stern, Ian P.; Collaboration: ADMX Collaboration; ADMX-HF Collaboration

    2014-06-24

    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 μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV 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.

  12. Axion dark matter searches

    SciTech Connect

    Stern, Ian P.

    2014-01-01

    We report 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 μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV 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.

  13. Dark matter axions revisited

    NASA Astrophysics Data System (ADS)

    Visinelli, Luca; Gondolo, Paolo

    2009-08-01

    We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae, and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma=(85±3)μeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma<15meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

  14. Windows on the axion

    SciTech Connect

    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.

  15. Axions from wall decay

    SciTech Connect

    Chang, S; Hagmann, C; Sikivie, P

    2001-01-08

    The authors discuss the decay of axion walls bounded by strings and present numerical simulations of the decay process. In these simulations, the decay happens immediately, in a time scale of order the light travel time, and the average energy of the radiated axions is {approx_equal} 7m{sub a} for v{sub a}/m{sub a} {approx_equal} 500. is found to increase approximately linearly with ln(v{sub a}/m{sub a}). Extrapolation of this behavior yields {approx_equal} 60 m{sub a} in axion models of interest.

  16. UV Completion of Axion

    SciTech Connect

    Choi, Kang-Sin

    2008-11-23

    A multiple number of global U(1)s, arising from accidental symmetries up to a certain order of the potential, enjoy lowering the axion decay constant from UV-scale and evading supersymmetric Fayet-Illiopoulos term constraints.

  17. Axion dark matter searches

    DOE PAGESBeta

    Stern, Ian P.

    2014-01-01

    We report 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 μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axionsmore » 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.« less

  18. Hierarchical axion inflation.

    PubMed

    Ben-Dayan, Ido; Pedro, Francisco Gil; Westphal, Alexander

    2014-12-31

    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 nonperturbative 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. PMID:25615300

  19. The QCD axion from aligned axions and diphoton excess

    NASA Astrophysics Data System (ADS)

    Higaki, Tetsutaro; Jeong, Kwang Sik; Kitajima, Naoya; Takahashi, Fuminobu

    2016-04-01

    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.

  20. Inflationary axion cosmology.

    NASA Astrophysics Data System (ADS)

    Lyth, D. H.

    The author has revisited inflationary axion cosmology. The treatment involves fewer assumptions than in the past, and he arrives at a scenario specified by the values of three parameters fa/N, Nθ¯, and Nσθ (√2fa is the vacuum value of the modulus of the Peccei-Quinn field, θ and σθ are the mean and rms dispersion of its phase θ just before the axion mass switches on, and N is the number of distinct vacuum values of θ once the mass has turned on). The following conclusions are presented: first, axionic domain walls can be cosmologically interesting only if fa/N is within an order of magnitude of its extreme astrophysical lower bound 2×108GeV. Second, the axion density perturbation can be either Gaussian or of the χ2type, but the latter case is likely only if fa/N ≤ 1010GeV. Third, at least in the absence of walls the axion density perturbation can probably not become big enough to be the cause of the observed structure, though the non-Gaussian case requires further investigation. Finally, the author makes the additional assumption that interactions of the Peccei-Quinn field do not alter the effective value of fa, while relevant scales leave the horizon during inflation. This leads to the strong bound on the inflationary energy density.

  1. Axion domain wall baryogenesis

    SciTech Connect

    Daido, Ryuji; Kitajima, Naoya; Takahashi, Fuminobu

    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.

  2. Search for solar axions

    NASA Astrophysics Data System (ADS)

    Newman, Seth Aaron

    Peccei and Quinn proposed an elegant solution for restoring CP symmetry to the QCD Lagrangian [37]. This method includes an additional global U(1) symmetry included in the QCD Lagrangian which is spontaneously broken at a high energy scale, fa. Breaking the symmetry generates a Nambu-Goldstone boson called the axion. Although there are various detection mechanisms that search for the axion, this thesis focuses on the the axio-electric effect. The axio-electric is similar to the photo-electric effect in that an axion is absorbed by an atom which subsequently emits an electron. The electron's energy is equivalent to the incoming axion energy minus the binding energy. The higher shell electrons immediately replenish the missing binding energy yielding a single energy peak at the incoming axion's energy. The 14.4 keV M1 transition of 57Fe is one possible axion source. The development of an optimum trigger algorithm has lowered the threshold for analysis in TeO2 bolometers to a few keV making an axion signature accessible to CUORE related R&D experiments such as the Chinese Crystal Validation Runs (CCVR) and Three Towers Test (TTT). These TeO2 crystal detectors have masses 750 and 790 grams, respectively. Each crystal has a stabilization heater and a germanium thermometer attached to its surface by an epoxy glue. The two previous experiments are R&D tests for the upcoming larger experiment, CUORE. CUORE will be made of 988 TeO2 crystals arranged in 19 towers with 13 floors each, each floor with 4 detectors. This thesis examined 87.01 kg·days of Three Towers data for an axion signal. A peak is observed in the region of interest with a statistical significance less than 1sigma over the expected background fluctuations, yielding a total background rate of 0.185 +/- 0.001 (Stat.) +/- 0.006 (Syst.) Counts/kg/day at 95% C.L. This places an experimental limit on the coupling constant fa of f a (S = 0.50) ≥ 1.16 x 106 GeV at 95% C.L. Projecting the TTT result to the CUORE

  3. Composite accidental axions

    NASA Astrophysics Data System (ADS)

    Redi, Michele; Sato, Ryosuke

    2016-05-01

    We present several models where the QCD axion arises accidentally. Confining gauge theories can generate axion candidates whose properties are uniquely determined by the quantum numbers of the new fermions under the Standard Model. The Peccei-Quinn symmetry can emerge accidentally if the gauge theory is chiral. We generalise previous constructions in a unified framework. In some cases these models can be understood as the deconstruction of 5-dimensional gauge theories where the Peccei-Quinn symmetry is protected by locality but more general constructions are possible.

  4. The lifetime of axion stars

    NASA Astrophysics Data System (ADS)

    Eby, Joshua; Suranyi, Peter; Wijewardhana, L. C. R.

    2016-05-01

    We investigate the decay of condensates of scalars in a field theory defined by V (𝒜) = m2f2[1 ‑cos(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, 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 δx ˜ R ˜ 1/(maΔ), where R is the radius of the star and Δ = 1 ‑ E0 2/ma 2. Here ma and E0 are the mass, and the ground state energy of the bound axion. Then the momentum distribution of axions has a width of δp ˜ maΔ. At strong binding, Δ = 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 transition rate Γ ˜ ma. However, when Δ ≪ 1, the momentum distribution is more restricted, and as shown in this paper, the transition rate for creating a free axion decreases as exp(‑pδx) ˜exp(‑Δ‑1). Then sufficiently large, weakly bound axion stars, produced after the Big Bang, survive until the present time. We plot the region of their stability, limited by decay through axion loss and by gravitational instability, as a function of the mass of the axion and the mass of the star.

  5. Cosmological Consequences of String Axions

    SciTech Connect

    Kain, Ben

    2005-12-15

    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 H{sub inf} {approx}> 10{sup 13} 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 {approx}< {Lambda}{sub QCD}.

  6. Mississippi State Axion Search

    NASA Astrophysics Data System (ADS)

    Madsen, Kris; Mississippi State Axion Search Collaboration

    2013-10-01

    Ever since the Peccei-Quinn Theory was proposed in 1977 as a possible solution to the strong CP problem, the therein postulated Axion, a weakly interacting boson, has been much sought after. The Mississippi State Axion Search is an attempt to improve the limit in the mass-coupling parameter space by using a variation of the Light Shining Through a Wall (LSW) technique. A vacuum sealed and RF shielded cavity is partitioned by a lead wall. EM waves at a frequency between 420 and 430 MHz are amplified by SR-550 and SR-510 amplifiers, broadcast from an antenna on one side of the lead wall and pass through an intense magnetic field. Theory predicts that in the presence of such a magnetic field, axions can be produced from photons via the Primakoff effect. Any axions generated will pass unimpeded to the other half of the cavity, regenerate into photons, and be detected as an excess in the signal picked up by the antenna on the far side. The Data Acquisition is handled by LABView based software running Measurement Computing drivers for two PCI DAQ cards: the DAS-08 handles the analog signals from the receiving antenna and monitors vital statistics in the cavity, while the DIO-24 provides the 1 kHz timing TTL pulse and allows remote control of the experiment's systems.

  7. Axion inflation with cross-correlated axion isocurvature perturbations

    NASA Astrophysics Data System (ADS)

    Kadota, Kenji; Kobayashi, Tatsuo; Otsuka, Hajime

    2016-01-01

    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.

  8. Solar axion flux from the axion-electron coupling

    SciTech Connect

    Redondo, Javier

    2013-12-01

    In non-hadronic axion models, where axions couple to electrons at tree level, the solar axion flux is completely dominated by the ABC reactions (Atomic recombination and deexcitation, Bremsstrahlung and Compton). In this paper the ABC flux is computed from available libraries of monochromatic photon radiative opacities (OP, LEDCOP and OPAS) by exploiting the relations between axion and photon emission cross sections. These results turn to be ∼ 30% larger than previous estimates due to atomic recombination (free-bound electron transitions) and deexcitation (bound-bound), which where not previously taken into account.

  9. Axions in astrophysics and cosmology

    SciTech Connect

    Sikivie, P.

    1984-07-01

    Axion models often have a spontaneously broken exact discrete symmetry. In that case, they have discretely degenerate vacua and hence domain walls. The properties of the domain walls, the cosmological catastrophe they produce and the ways in which this catastrophe may be avoided are explained. Cosmology and astrophysics provide arguments that imply the axion decay constant should lie in the range 10/sup 8/ GeV less than or equal to f/sub a/ less than or equal to 10/sup 12/ GeV. Reasons are given why axions are an excellent candidate to constitute the dark matter of galactic halos. Using the coupling of the axions to the electromagnetic field, detectors are described to look for axions floating about in the halo of our galaxy and for axions emitted by the sun. (LEW)

  10. Axions and SN1987A

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Turner, Michael S.; Brinkmann, R. P.

    1988-01-01

    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.

  11. Axion Bounds from Precision Cosmology

    SciTech Connect

    Raffelt, G. G.; Hamann, J.; Hannestad, S.; Mirizzi, A.; Wong, Y. Y. Y.

    2010-08-30

    Depending on their mass, axions produced in the early universe can leave different imprints in cosmic structures. If axions have masses in the eV-range, they contribute a hot dark matter fraction, allowing one to constrain m{sub a} in analogy to neutrinos. In the more favored scenario where axions play the role of cold dark matter and if reheating after inflation does not restore the Peccei-Quinn symmetry, the axion field provides isocurvature fluctuations that are severely constrained by precision cosmology. There remains a small sliver in parameter space where isocurvature fluctuations could still show up in future probes.

  12. Axions in String Theory

    SciTech Connect

    Svrcek, Peter; Witten, Edward; /Princeton, Inst. Advanced Study

    2006-06-09

    In the context of string theory, axions appear to provide the most plausible solution of the strong CP problem. However, as has been known for a long time, in many string-based models, the axion coupling parameter Fa is several orders of magnitude higher than the standard cosmological bounds. We re-examine this problem in a variety of models, showing that Fa is close to the GUT scale or above in many models that have GUT-like phenomenology, as well as some that do not. On the other hand, in some models with Standard Model gauge fields supported on vanishing cycles, it is possible for Fa to be well below the GUT scale.

  13. Cosmological limits on axions and axion-like particles

    NASA Astrophysics Data System (ADS)

    Cadamuro, Davide

    2012-10-01

    The axion is a pseudo-Nambu-Goldstone boson. It appears after the spontaneous breaking of the Peccei-Quinn symmetry, which was proposed to solve the strong-CP problem. Other pseudo-Nambu-Goldstone bosons, postulated in some extensions of the standard model of particle physics, are called axion-like particles (ALPs) if they share certain characteristics with the axion, in particular a coupling to two photons. Thus far, axion and ALP searches have been unsuccessful, indicating that their couplings have to be extremely weak. However, axions and ALPs could be responsible for some observable effects in astrophysics and cosmology, which can also be exploited to constrain the parameter space of these particles. We focus on limits coming from cosmology, which is an optimal field for studying axions and ALPs. In particular, we first investigate the possibility of a primordial population of axions and ALPs arising during the earliest epochs of the universe. The importance of this analysis lies on the fact that axions and ALPs are ideal dark matter candidates because of their faint interactions and their peculiar production mechanisms. Finally, we consider the consequences of the decay of such a population on specific cosmological observables, namely the photon spectrum of galaxies, the cosmic microwave background, the effective number of neutrino species, and the abundance of primordial elements. Our bounds constitute the most stringent probes of early decays and exclude a part of the ALP parameter space that is otherwise very difficult to test experimentally.

  14. Mississippi State Axion Search

    NASA Astrophysics Data System (ADS)

    Madsen, John

    2014-03-01

    The Mississippi State Axion Search (MASS) is an attempt to improve the limit on the mass coupling parameter of the Axion. The design features a sealed cavity partitioned by a lead wall into which RF power is transmitted. Another antenna on the far end of the cavity serves as the detector. The signal acquired by this antenna is fed through an integrator and a series of pre-amps and lock-ins before reaching the data acquisition system. The data acquisition system, written in the LabView front end DASYLab, operates at 1 kHz in synchronicity with a TTL pulse that resets the integrator. The value recorded by the DAQ is, therefore, the maximum voltage of integration in the millisecond period. The Axion signal would appear in the data as a voltage excess. Several measures have been implemented with more being developed to ensure the validity of detections. Large excesses are cut by an electronics system, and smaller anomalies will be excised in the data analysis. Results will also compared to a complete Monte Carlo simulation currently in development. Prajwal Mohanmurthy*, Dipangkar Dutta, Nicholas Fowler, Mikhail Gaerlan, Kris Madsen, Adam Powers, Amy Ray, David Reed, Robertsen Riehle, Mitra Shabestari, Zachary Windham, Zach Short.

  15. Electromagnetic detector for relic axions

    SciTech Connect

    Morris, D.E.

    1984-05-01

    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/c/sup 2//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 10/sup 6/, 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 4/sup 0/K, with noise temperature between 20/sup 0/K and 200/sup 0/K. 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/sup -6/ eV to 4x10/sup -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.

  16. Cosmological Constant and Axions in String Theory

    SciTech Connect

    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.

  17. Experimental Searches for the Axion and Axion-Like Particles

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Irastorza, Igor G.; Lamoreaux, Steven K.; Lindner, Axel; van Bibber, Karl A.

    2015-10-01

    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 article reviews the experimental situation on several fronts. The microwave cavity experiment is making excellent progress in the search for dark matter axions in the μeV range and may plausibly be extended up to 100 μeV. Within the past several years, however, researchers have realized that axions are pervasive throughout string theories, but with masses that fall naturally in the neV range, for which an NMR-based search is under development. Both searches for axions emitted from the Sun's burning core and purely laboratory experiments based on photon regeneration have recently made great progress, with ambitious projects proposed for the coming decade. Each of these campaigns has pushed the state of the art in technology, enabling large gains in sensitivity and mass reach. Furthermore, each modality has been exploited in order to search for more generalized axion-like particles, which we also discuss in this review. We are hopeful, even optimistic, that the next review of the subject will concern the discovery of the axion, its properties, and its exploitation as a probe of early universe cosmology and structure formation.

  18. Axionic mirage mediation

    SciTech Connect

    Nakamura, Shuntaro; Okumura, Ken-ichi; Yamaguchi, Masahiro

    2008-06-01

    Although 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 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 10{sup 10} GeV to 10{sup 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 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.

  19. Axion cold dark matter revisited

    NASA Astrophysics Data System (ADS)

    Visinelli, L.; Gondolo, P.

    2010-01-01

    We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae [1], and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma = (85 ± 3) μeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma < 15 meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

  20. Axion Isocurvature and Magnetic Monopoles.

    PubMed

    Nomura, Yasunori; Rajendran, Surjeet; Sanches, Fabio

    2016-04-01

    We propose a simple mechanism to suppress axion isocurvature fluctuations using hidden sector magnetic monopoles. This allows for the Peccei-Quinn scale to be of the order of the unification scale consistently with high scale inflation. PMID:27104700

  1. Axion Isocurvature and Magnetic Monopoles

    NASA Astrophysics Data System (ADS)

    Nomura, Yasunori; Rajendran, Surjeet; Sanches, Fabio

    2016-04-01

    We propose a simple mechanism to suppress axion isocurvature fluctuations using hidden sector magnetic monopoles. This allows for the Peccei-Quinn scale to be of the order of the unification scale consistently with high scale inflation.

  2. FUN with monopoles and axions

    NASA Astrophysics Data System (ADS)

    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.

  3. No axions from the Sun

    NASA Astrophysics Data System (ADS)

    Roncadelli, M.; Tavecchio, F.

    2015-06-01

    Preliminary evidence of solar axions in XMM-Newton observations has quite recently been claimed by Fraser et al. as an interpretation of their detection of a seasonally-modulated excess of the X-ray background. Within such an interpretation, these authors also estimate the axion mass to be ma ≃ 2.3 × 10-6 eV. Since an axion with this mass behaves as a cold dark matter particle, according to the proposed interpretation the considered detection directly concerns cold dark matter as well. So, the suggested interpretation would lead to a revolutionary discovery if confirmed. Unfortunately, we have identified three distinct problems in this interpretation of the observed result of Fraser et al. which ultimately imply that the detected signal - while extremely interesting in itself - cannot have any relation with hypothetical axions produced by the Sun. Thus, a physically consistent interpretation of the observed seasonally-modulated X-ray excess still remains an exciting challenge.

  4. Axion dynamics in wormhole background

    SciTech Connect

    Rey, S.

    1989-05-15

    When axions are coupled to gravity, it is known that wormholes exist asgravitational instantons. These wormholes break global U(1) symmetry explicitlythus giving rise to the wormhole-induced low-energy effective Lagrangian. Wederive systematically this effective Lagrangian to lower orders in thederivative expansion. The role of U(1) symmetry to the third-quantized fieldtheory of topology change and the invisible-axion phenomenology in the wormholebackground are also discussed.

  5. Ultrasensitive Searches for the Axion

    SciTech Connect

    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.

  6. Two applications of axion electrodynamics

    NASA Technical Reports Server (NTRS)

    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.

  7. Properties of noncommutative axionic electrodynamics

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Schmidt, Iván

    2007-07-01

    Using the gauge-invariant but path-dependent variables formalism, we compute the static quantum potential for noncommutative axionic electrodynamics, and find a radically different result than the corresponding commutative case. We explicitly show that the static potential profile is analogous to that encountered in both non-Abelian axionic electrodynamics and in Yang-Mills theory with spontaneous symmetry breaking of scale symmetry.

  8. Isocurvature bounds on axions revisited

    SciTech Connect

    Beltran, Maria; Garcia-Bellido, Juan; Lesgourgues, Julien

    2007-05-15

    The axion is one of the best motivated candidates for particle dark matter. We study and update the constraints imposed by the recent CMB and LSS experiments on the mass of axions produced by the misalignment mechanism, as a function of both the inflationary scale and the reheating temperature. Under some particular although not unconventional assumptions, the axion induces isocurvature perturbations with an amplitude too large to be compatible with observations. Specifically, for inflation taking place at intermediate energy scales, we derive some restrictive limits which can only be evaded by assuming an efficient reheating mechanism, with T{sub rh}>10{sup 11} GeV. Chaotic inflation with a quadratic potential is still compatible with the axion scenario, provided that the Peccei-Quinn scale f{sub a} is close to 10{sup 10} or 10{sup 11} GeV. Isocurvature bounds eliminate the possibility of a larger f{sub a} and a small misalignment angle. We find that isocurvature constraints on the axion scenario must be taken into account whenever the scale of inflation is above 10{sup 12} GeV; below this scale, axionic isocurvature modes are too small to be probed by current observations.

  9. Dark matter axions and caustic rings

    SciTech Connect

    Sikivie, P.

    1997-11-01

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

  10. Axions: Bose Einstein condensate or classical field?

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha

    2015-05-01

    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.

  11. New atomic probes for dark matter detection: Axions, axion-like particles and topological defects

    NASA Astrophysics Data System (ADS)

    Stadnik, Yevgeny V.; Flambaum, Victor V.

    2014-11-01

    We present a brief overview of recently proposed detection schemes for axion, axion-like pseudoscalar particle and topological defect dark matter. We focus mainly on the possibility of using atomic and molecular systems for dark matter detection. For axions and axion-like particles, these methods are complementary probes to ongoing photon-axion interconversion experiments and astrophysical observations. For topological defects, these methods are complementary to conventional astrophysical search schemes based on gravitational signatures.

  12. Axion cooling of neutron stars

    NASA Astrophysics Data System (ADS)

    Sedrakian, Armen

    2016-03-01

    Cooling simulations of neutron stars and their comparison with the data from thermally emitting x-ray sources put constraints on the properties of axions, and by extension, of any light pseudoscalar dark matter particles, whose existence has been postulated to solve the strong-C P 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 formulas 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 nonaccreted iron and accreted light-element envelopes, and a range of nucleon-axion couplings. The models are based on an equation state predicting conservative physics of superdense nuclear matter that does not allow for the onset of fast cooling processes induced by phase transitions to non-nucleonic forms of matter or high proton concentration. The cooling tracks in the temperature vs age plane were confronted with the (time-averaged) measured surface temperature of the central compact object in the Cas A supernova remnant as well as surface temperatures of three nearby middle-aged thermally emitting pulsars. We find that the axion coupling is limited to fa/107 GeV ≥(5 - 10 ) , which translates into an upper bound on axion mass ma≤(0.06 - 0.12 ) eV for Peccei-Quinn charges of the neutron |Cn|˜0.04 and proton |Cp|˜0.4 characteristic for hadronic models of axions.

  13. Interaction of axions with relativistic spinning particles

    NASA Astrophysics Data System (ADS)

    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.

  14. Planckian axions in string theory

    NASA Astrophysics Data System (ADS)

    Bachlechner, Thomas C.; Long, Cody; McAllister, Liam

    2015-12-01

    We argue that super-Planckian diameters of axion fundamental domains can arise in Calabi-Yau compactifications of string theory. In a theory with N axions θ i , the fundamental domain is a polytope defined by the periodicities of the axions, via constraints of the form - π < Q i j θ j < π. We compute the diameter of the fundamental domain in terms of the eigenvalues f 1 2 ≤ … ≤ f N 2 of the metric on field space, and also, crucially, the largest eigenvalue of ( QQ ⊤)-1. At large N, QQ ⊤ approaches a Wishart matrix, due to universality, and we show that the diameter is at least Nf N , exceeding the naive Pythagorean range by a factor > √{N} . This result is robust in the presence of P > N constraints, while for P = N the diameter is further enhanced by eigenvector delocalization to N 3/2 f N . We directly verify our results in explicit Calabi-Yau compactifications of type IIB string theory. In the classic example with h 1,1 = 51 where parametrically controlled moduli stabilization was demonstrated by Denef et al. in [1], the largest metric eigenvalue obeys f N ≈ 0.013 M pl. The random matrix analysis then predicts, and we exhibit, axion diameters ≈ M pl for the precise vacuum parameters found in [1]. Our results provide a framework for pursuing large-field axion inflation in well-understood flux vacua.

  15. Axion landscape and natural inflation

    NASA Astrophysics Data System (ADS)

    Higaki, Tetsutaro; Takahashi, Fuminobu

    2015-05-01

    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.

  16. Axion as a cold dark matter candidate: analysis to third order perturbation for classical axion

    NASA Astrophysics Data System (ADS)

    Noh, Hyerim; Hwang, Jai-chan; Park, Chan-Gyung

    2015-12-01

    We investigate aspects of axion as a coherently oscillating massive classical scalar field by analyzing third order perturbations in Einstein's gravity in the axion-comoving gauge. The axion fluid has its characteristic pressure term leading to an axion Jeans scale which is cosmologically negligible for a canonical axion mass. Our classically derived axion pressure term in Einstein's gravity is identical to the one derived in the non-relativistic quantum mechanical context in the literature. We present the general relativistic continuity and Euler equations for an axion fluid valid up to third order perturbation. Equations for axion are exactly the same as that of a zero-pressure fluid in Einstein's gravity except for an axion pressure term in the Euler equation. Our analysis includes the cosmological constant.

  17. Resonantly-enhanced axion-photon regeneration

    SciTech Connect

    Mueller, Guido; Sikivie, Pierre; Tanner, David B.; Bibber, Karl van

    2010-08-30

    A resonantly-enhanced photon-regeneration experiment to search for the axion or axion-like particles is discussed. Photons enter a strong magnetic field and some are converted to axions; the axions can pass through an opaque wall and some may convert back to photons in a second high-field region. The photon regeneration is enhanced by employing matched Fabry-Perot optical cavities, with one cavity within the axion generation magnet and the second within the photon regeneration magnet. The optics for this experiment are discussed, with emphasis on the alignment of the two cavities.

  18. Axion dark matter detection using atomic transitions.

    PubMed

    Sikivie, P

    2014-11-14

    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 to be an appropriate approach to axion dark matter detection in the 10^{-4}  eV mass range. PMID:25432034

  19. Theory of Light Scattering in Axion Electrodynamics

    NASA Astrophysics Data System (ADS)

    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.

  20. Axion dark matter: strings and their cores

    NASA Astrophysics Data System (ADS)

    Fleury, Leesa; Moore, Guy D.

    2016-01-01

    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.

  1. Axions and inflation: Vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Lyth, D. H.

    1992-05-01

    Cosmological consequences of the Peccei-Quinn field ψ=reiθ/ √2 are explored. It has a Mexican-hat potential W=1/4λ(r2-f2a)2. During inflation the potential may be modified so that fa has a different effective value fa1; it is assumed that r sits in the vacuum at r=fa1. After inflation the temperature is supposed to be less than fa so that r=fa, and the only degree of freedom is the axion field faθ. It has a Gaussian inhomogeneity coming from the vacuum fluctuation of θ during inflation. When the axion mass ma(T) becomes significant at T~1 GeV, θ has dispersion σθ~=(4/2π)(H1/fa1) and some mean θ¯ (in the observable Universe). The axion potential is U(θ)=(79 MeV)4(1-cosNθ), and the ensuing cosmology is determined by the three parameters fa/N, Nθ¯, and Nσθ. The entire domain of parameter space is considered, including the regime where the axion density perturbation is non-Gaussian and the regime where axionic domain walls are produced. Observational constraints on the parameters are established. At the end of the paper the additional assumption is made that during inflation the vacuum is at r=fa. Unless fa/N is near the Planck scale and axions make up only a small fraction of the dark matter, this leads to the bound V1/41<2×1015 GeV, where V1 is the energy density during inflation, at the epoch when the observable Universe leaves the horizon.

  2. Backreacted axion field ranges in string theory

    NASA Astrophysics Data System (ADS)

    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.

  3. Cosmological constraints on axionic dark radiation from axion-photon conversion in the early Universe

    SciTech Connect

    Higaki, Tetsutaro; Nakayama, Kazunori; Takahashi, Fuminobu E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp

    2013-09-01

    Axions seem ubiquitous in string theories and some of them may be produced non-thermally by heavy scalar decays, contributing to dark radiation. We study various cosmological effects of photons produced from the axionic dark radiation through axion-photon conversion in the presence of primordial magnetic fields, and derive tight constraints on the combination of the axion-photon coupling and the primordial magnetic field.

  4. Rotating drops of axion dark matter

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha; Schwetz, Thomas

    2016-06-01

    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 10-13M⊙ (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 . 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.

  5. R-axion detection at LHC

    SciTech Connect

    Goh, Hock-Seng; 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.

  6. Axion induced oscillating electric dipole moments

    SciTech Connect

    Hill, Christopher T.

    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 ma 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.

  7. Searching for Dark-Matter Axions

    NASA Astrophysics Data System (ADS)

    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 <10-3 eV/c2) would have extraordinarily feeble interactions with normal matter and radiation, and these axions have the properties of an ideal dark-matter candidate. Axions have been searched for since their inception. However, light axions constituting dark matter are so feebly coupled that it is only recently that detection 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.

  8. Search for Axions with the CDMS Experiment

    SciTech Connect

    Ahmed, Z.; Akerib, D.S.; Arrenberg, S.; Bailey, C.N.; Balakishiyeva, D.; Baudis, L.; Bauer, D.A.; Beaty, J.; Brink, P.L.; Bruch, T.; Bunker, R.; /UC, Santa Barbara /Stanford U., Phys. Dept.

    2009-02-01

    We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local Galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling g{sub a{gamma}{gamma}} of 2.4 x 10{sup ?9} GeV{sup -1} at the 95% confidence level for an axion mass less than 0.1 keV/c{sup 2}. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The Galactic axion search analysis sets a world-leading experimental upper limit on the axio-electric coupling g{sub a{bar e}e} of 1.4 x 10{sup -12} at the 90% confidence level for an axion mass of 2.5 keV/c{sup 2}. This analysis excludes an interpretation of the DAMA annual modulation result in terms of Galactic axion interactions for axion masses above 1.4 keV/c{sup 2}.

  9. A microwave cavity search for axions

    NASA Astrophysics Data System (ADS)

    Tanner, D. B.

    2007-04-01

    The mass of the axion, a hypothetical elementary particle proposed as a solution to the ``strong-CP'' problem, is constrained by experimental and astrophysical considerations to a range where the axion is a very plausible cold dark matter candidate. This weakly-interacting dark matter particle could constitute the halo of our galaxy. In the Axion Dark Matter eXperiment (ADMX), halo axions flow through a microwave resonant cavity permeated by a static magnetic field, where some convert into microwave photons. These photons are detected by an ultralow-noise receiver. The ADMX Collaboration has set limits on the axion-to-photon coupling and/or local axion halo mass density for axion mass between 1.9 and 3.3 μeV. Consideration of phase-space structure of the axion flow, which predicts extremely sharp peaks in the axion kinetic-energy spectrum, improves the limit. Presently underway is an upgrade to the experiment, using SQUID RF amplifiers, which will improve the performance by more than a factor of 10.Work done with L.D. Duffy, P. Sikivie, University of Florida, S.J. Asztalos, G. Carosi, D. Carter, C. Hagmann, D. Kinion, L.J. Rosenberg, K. van Bibber, LLNL, D.B. Yu, MIT, and R.F. Bradley, NRAO.

  10. Neutrino-axion-dilaton interconnection

    NASA Astrophysics Data System (ADS)

    Bertolini, Stefano; Di Luzio, Luca; Kolešová, Helena; Malinský, Michal; Vasquez, Juan Carlos

    2016-01-01

    We show that a recently proposed framework that provides a simple connection between Majorana neutrinos and an invisible axion in minimal scalar extensions of the standard electroweak model can be naturally embedded in a classically scale-invariant setup. The explicit breaking of the scale invariance à la Coleman-Weinberg generates the Peccei-Quinn and electroweak scales. The spontaneous breaking of the chiral U (1 )PQ triggers the generation of neutrino masses via Type-II seesaw and, at the same time, provides a dynamical solution to the strong C P problem as well as the axion as a dark matter candidate. The electroweak and neutrino mass scales are obtained via a technically natural ultraweak limit of the singlet scalar interactions. Accordingly, a realistic and perturbatively stable scalar spectrum, possibly in the reach of the LHC, is naturally obtained. A very light pseudodilaton characterizes such a setting. The vacuum stability of the extended setup is discussed.

  11. Vacuum selection on axionic landscapes

    NASA Astrophysics Data System (ADS)

    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.

  12. Some Considerations about Podolsky-Axionic Electrodynamics

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio

    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 θ.

  13. Axion string dynamics I: 2+1D

    NASA Astrophysics Data System (ADS)

    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.

  14. Fermion production during and after axion inflation

    SciTech Connect

    Adshead, Peter; Sfakianakis, Evangelos I.

    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.

  15. Axion BEC: A model beyond CDM

    NASA Astrophysics Data System (ADS)

    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

  16. Large field inflation from axion mixing

    NASA Astrophysics Data System (ADS)

    Shiu, Gary; Staessens, Wieland; Ye, Fang

    2015-06-01

    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 Stückelberg 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 intersecting D6-brane models on and Type IIB intersecting D7-brane models on Swiss-Cheese Calabi-Yau orientifolds.

  17. Axion mass estimates from resonant Josephson junctions

    NASA Astrophysics Data System (ADS)

    Beck, Christian

    2015-03-01

    Recently it has been proposed that dark matter axions from the galactic halo can produce a small Shapiro step-like signal in Josephson junctions whose Josephson frequency resonates with the axion mass (Beck, 2013). Here we show that the axion field equations in a voltage-driven Josephson junction environment allow for a nontrivial solution where the axion-induced electrical current manifests itself as an oscillating supercurrent. The linear change of phase associated with this nontrivial solution implies the formal existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. We derive a condition for the design of Josephson junction experiments so that they can act as optimum axion detectors. Four independent recent experiments are discussed in this context. The observed Shapiro step anomalies of all four experiments consistently point towards an axion mass of (110±2) μeV. This mass value is compatible with the recent BICEP2 results and implies that Peccei-Quinn symmetry breaking was taking place after inflation.

  18. Experimental searches for galactic halo axions.

    PubMed

    van Bibber, Karl A; Kinion, S Darin

    2003-11-15

    A very light axion would be copiously produced during the Big Bang as a zero-temperature Bose gas, and it would possess vanishingly small couplings to matter and radiation. It thus represents an ideal cold dark matter candidate. Galactic halo axions may be detected by their resonant conversion to microwave photons in a high-Q cavity permeated by a strong magnetic field. A large-scale search for the axion is ongoing in the US with sufficient sensitivity to see axions of plausible model couplings. Dramatic breakthroughs in the development of near-quantum limited superconducting quantum interference device amplifiers promise to improve the sensitivity of the experiment by a factor of 30 in the near future. In Japan, a group has been developing a Rydberg atom single-quantum detector as an alternative to linear amplifiers for a microwave-cavity axion experiment. Should the axion be discovered, the predicted fine structure in the axion signal would be rich in information about the history of galactic formation. PMID:14667317

  19. CAST: An Inspiring Axion Helioscope ala Sikivie

    SciTech Connect

    Zioutas, K.; Anastassopoulos, V.; Tsagri, M.; Semertzidis, Y.; Papaevangelou, T.

    2010-08-30

    CAST is a data taking axion helioscope using a recycled LHC test magnet, CERN's detector technology and cryogenics expertise. An imaging X-ray telescope improves substantially the detection sensitivity and axion-ID. Massive axion-like particles of the Kaluza-Klein type were first introduced to explain the paradox of the hot corona, which is even hotter at locations overlying magnetic spots. This is suggesting that the CAST detection principle might be at work there, but being somehow modified and performing better. Remarkably, the density profile of the Sun allows for resonance crossing (m{sub axion}c{sup 2{approx_equal}}h{omega}{sub plasma}), which axion helioscopes are aiming to reach. The restless Sun favours this occasionally even further. Then, such processes can give rise to a chimera of converted axions or the like, making the Sun appear, within known physics, as mysterious and unpredictable as it is. CAST axion limits were used to conclude also for the hidden sector paraphotons. This is then suggestive for novel helioscopes for exotica like paraphotons, chameleons, etc. Pierre Sikivie's pioneering idea was to use a magnetic field as a catalyst to transform particles from the dark sector to ours, and vice versa.

  20. The next generation of axion helioscopes: The international axion observatory (IAXO)

    DOE PAGESBeta

    Vogel, J. K.; Armengaud, E.; Avignone, F. T.; Betz, M.; Brax, P.; Brun, P.; Cantatore, G.; Carmona, J. M.; Carosi, G. P.; Caspers, F.; et al

    2015-03-24

    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 ~ 0.25 eV. 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 ~ 20more » 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 60 cm diameter magnet bores is equipped with x-ray optics focusing the signal photons into ~ 0.2 cm² spots that are imaged by very low background x-ray detectors. The magnet will be built into a structure with elevation and azimuth drives that will allow solar tracking for 12 hours each day. This contribution is a summary of our papers [1, 2, 3] and we refer to these for further details.« less

  1. The next generation of axion helioscopes: The international axion observatory (IAXO)

    SciTech Connect

    Vogel, J. K.; Armengaud, E.; Avignone, F. T.; 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.; ten Kate, H.; Tomas, A.; Troitsky, S.; Vafeiadis, T.; van Bibber, K.; Vedrine, P.; Villar, J. A.; Walckiers, L.; Weltman, A.; Wester, W.; Yildiz, S. C.; Zioutas, K.

    2015-03-24

    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 g down to a few ×10⁻¹² GeV⁻¹ for a wide range of axion masses up to ~ 0.25 eV. 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 60 cm diameter magnet bores is equipped with x-ray optics focusing the signal photons into ~ 0.2 cm² spots that are imaged by very low background x-ray detectors. The magnet will be built into a structure with elevation and azimuth drives that will allow solar tracking for 12 hours each day. This contribution is a summary of our papers [1, 2, 3] and we refer to these for further details.

  2. Recent constraints on axion-photon and axion-electron coupling with the CAST experiment

    DOE PAGESBeta

    Ruz, J.; Vogel, J. K.; Pivovaroff, M. J.

    2015-03-24

    The CERN Axion Solar Telescope (CAST) is a helioscope looking for axions arising from the solar core plasma and arriving to Earth. The experiment, located in Geneva (Switzerland) is able to follow the Sun during sunrise and sunset. Four x-ray detectors mounted on both ends of the magnet wait for photons from axion-to-photon conversion due to the Primakoff effect. Up to date, with the completion of Phases I and II, CAST has been looking for axions that could be produced in the Sun by both, hadronic and non-hadronic mechanisms.

  3. New potentials for string axion inflation

    NASA Astrophysics Data System (ADS)

    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.

  4. Wormhole effect on the superstring axion

    SciTech Connect

    Kim, J.E.

    1989-04-15

    Wormhole solutions can arise from the third-rank field strength H/sub ..mu..//sub ..nu..//sub rho/ which has a gluon anomaly. The superstring axion has this property. The effect of these wormholes on axion cosmology is studied. To save the superstring axion energy-density problem, theta-bar is /similar to/10/sup -3/ or ..lambda../sub 0//sup 1/4/ is /similar to/10 keV at the QCD chiral-symmetry-breaking scale.

  5. The emerging case for axion dark matter

    NASA Astrophysics Data System (ADS)

    Sikivie, P.

    2011-01-01

    Dark matter axions form a rethermalizing Bose-Einstein condensate. This provides an opportunity to distinguish axions from other forms of dark matter on observational grounds. I show that if the dark matter is axions, tidal torque theory predicts a specific structure for the phase space distribution of the halos of isolated disk galaxies, such as the Milky Way. This phase space structure is precisely that of the caustic ring model, for which observational support had been found earlier. The other dark matter candidates predict a different phase space structure for galactic halos.

  6. Is the relaxion an axion?

    NASA Astrophysics Data System (ADS)

    Gupta, Rick S.; Komargodski, Zohar; Perez, Gilad; Ubaldi, Lorenzo

    2016-02-01

    We consider the recently proposed cosmological relaxation mechanism where the hierarchy problem is ameliorated, and the electroweak (EW) scale is dynamically selected by a slowly rolling axion field. We argue that, in its simplest form, the construction breaks a gauge symmetry that always exists for pseudo-Nambu-Goldstone bosons (in particular the axion). The small parameter in the relaxion model is therefore not technically natural as it breaks a gauge symmetry rather than global symmetries only. The consistency of the theory generically implies that the cutoff must lie around the electroweak scale, but not qualitatively higher. We discuss several ways to evade the above conclusion. Some of them may be sufficient to increase the cutoff to the few-TeV range (and therefore may be relevant for the little-hierarchy problem). To demonstrate the ideas in a concrete setting we consider a model with a familon, the Nambu-Goldstone boson of a spontaneously broken chiral flavor symmetry. The model has some interesting collider-physics aspects and contains a viable weakly interacting dark matter candidate.

  7. Axion stars and fast radio bursts

    NASA Astrophysics Data System (ADS)

    Iwazaki, Aiichi

    2015-01-01

    We show a possible origin of fast radio bursts. They arise from the collisions between axion stars and neutron stars. The bursts are emitted in atmospheres of the neutron stars. The observed frequencies of the bursts are given by the axion mass ma such as ma/2 π ≃2.4 GHz (ma/10-5 eV ) . By the comparison of the theoretical with observed event rate ˜10-3 per year in a galaxy, we can determine the mass ˜10-12M⊙ of the axion stars. The mass is identical to the one estimated as the masses of axion miniclusters. Using these values, we can explain short durations (˜ms ) and amount of radiation energies (˜1043 GeV ) of the bursts.

  8. Axions as hot and cold dark matter

    SciTech Connect

    Jeong, Kwang Sik; Kawasaki, Masahiro; Takahashi, Fuminobu E-mail: kawasaki@icrr.u-tokyo.ac.jp

    2014-02-01

    The presence of a hot dark matter component has been hinted at 3σ by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu-Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f{sub a}∼axions, pseudo Nambu-Goldstone bosons coupled to the standard model sector through the Higgs portal, and axions produced by modulus decay.

  9. Axions from cosmic string and wall decay

    SciTech Connect

    Hagmann, Chris

    2010-08-30

    If inflation occurred with a reheat temperature > T{sub PQ}, axions from the decay of global axion strings and domain walls would make an important contribution to the cosmological energy density, comparable to that from vacuum misalignment. Several groups have numerically studied the evolution of axion strings and walls in the past, however substantial uncertainties remain in their contribution to the present density {Omega}{sub a,string+wall{approx}}1-100(f{sub a}/10{sup 12} GeV){sup 7/6}, where f{sub a} is the axion decay constant. I will describe the numerical methods used in our simulations and show results for several string and wall configurations.

  10. Axions from cosmic string and wall decay

    SciTech Connect

    Hagmann, C A

    2010-03-10

    If inflation occurred with a reheat temperature > T{sub PQ}, axions from the decay of global axion strings and domain walls would make an important contribution to the cosmological energy density, comparable to that from vacuum misalignment. Several groups have numerically studied the evolution of axion strings and walls in the past, however substantial uncertainties remain in their contribution to the present density {Omega}{sub a,string+wall} {approx} 1-100 (f{sub a}/10{sup 12} GeV){sup 7/6}, where f{sub a} is the axion decay constant. I will describe the numerical methods used in our simulations and show results for several string and wall configurations.

  11. Dark-matter QCD-axion searches

    PubMed Central

    Rosenberg, Leslie J

    2015-01-01

    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

  12. Dark-matter QCD-axion searches.

    PubMed

    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

  13. Update of axion CDM energy density

    SciTech Connect

    Huh, Ji-Haeng

    2008-11-23

    We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale {lambda}{sub QCD}, the current quark masses m{sub q}'s and the Peccei-Quinn scale F{sub a}, including firstly introduced 1.85 factor which is from the initial overshoot.

  14. Axion Research at CAPP/IBS

    NASA Astrophysics Data System (ADS)

    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.

  15. Planckian axions and the Weak Gravity Conjecture

    NASA Astrophysics Data System (ADS)

    Bachlechner, Thomas C.; Long, Cody; McAllister, Liam

    2016-01-01

    Several recent works [1-3] have claimed that the Weak Gravity Conjecture (WGC) excludes super-Planckian displacements of axion fields, and hence large-field axion inflation, in the absence of monodromy. We argue that in theories with N ≫ 1 axions, super-Planckian axion diameters D are readily allowed by the WGC. We clarify the non-trivial relationship between the kinetic matrix K — unambiguously defined by its form in a Minkowski-reduced basis — and the diameter of the axion fundamental domain, emphasizing that in general the diameter is not solely determined by the eigenvalues f 1 2 ≤ ṡ ṡ ṡ ≤ f N 2 of K: the orientations of the eigenvectors with respect to the identifications imposed by instantons must be incorporated. In particular, even if one were to impose the condition f N < M pl, this would imply neither D < M pl nor D < √{N}{M}_{pl} . We then estimate the actions of instantons that fulfill the WGC. The leading instanton action is bounded from below by S≥ {S}{M}_{pl}/{f}_N , with {S} a fixed constant, but in the universal limit S≳ S√{N} {M}_{pl}/{f}_N . Thus, having f N > M pl does not immediately imply the existence of unsuppressed higher harmonic contributions to the potential. Finally, we argue that in effective axion-gravity theories, the zero-form version of the WGC can be satisfied by gravitational instantons that make negligible contributions to the potential.

  16. Axions and the galactic angular momentum distribution

    NASA Astrophysics Data System (ADS)

    Banik, N.; Sikivie, P.

    2013-12-01

    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 He4 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 composed of axions.

  17. Windows on the axion. [quantum chromodynamics (QCD)

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1989-01-01

    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(-12)eV is approx. less than m(a) which is approx. less than 10(6)eV, some 18 orders-of-magnitude. Laboratory experiments have excluded masses greater than 10(4)eV, leaving unprobed some 16 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 producting 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(-6)eV is approx. less than m(a) is approx. less than 10(-3)eV and 1eV is approx. less than m(a) is approx. less than 5eV (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.

  18. Large-scale search for dark-matter axions

    SciTech Connect

    Hagmann, C.A., LLNL; Kinion, D.; Stoeffl, W.; Van Bibber, K.; Daw, E.J.; McBride, J.; Peng, H.; Rosenberg, L.J.; Xin, H.; Laveigne, J.; Sikivie, P.; Sullivan, N.S.; Tanner, D.B.; Moltz, D.M.; Powell, J.; Clarke, J.; Nezrick, F.A.; Turner, M.S.; Golubev, N.A.; Kravchuk, L.V.

    1998-01-01

    Early results from a large-scale search for dark matter axions are presented. In this experiment, axions constituting our dark-matter halo may be resonantly converted to monochromatic microwave photons in a high-Q microwave cavity permeated by a strong magnetic field. Sensitivity at the level of one important axion model (KSVZ) has been demonstrated.

  19. Lattice QCD input for axion cosmology

    NASA Astrophysics Data System (ADS)

    Berkowitz, Evan; Buchoff, Michael I.; Rinaldi, Enrico

    2015-08-01

    One intriguing beyond-the-Standard-Model particle is the QCD axion, which could simultaneously provide a solution to the Strong C P Problem and account for some, if not all, of the dark matter density in the Universe. This particle is a pseudo-Nambu-Goldstone boson of the conjectured Peccei-Quinn symmetry of the Standard Model. Its mass and interactions are suppressed by a heavy symmetry-breaking scale, fa, the value of which is roughly greater than 109 GeV (or, conversely, the axion mass, ma, is roughly less than 104 μ 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 temperature-dependent QCD free energy with respect to the C P -violating phase, θ . However, this quantity is generically nonperturbative, and previous calculations have only employed instanton models at the high temperatures of interest (roughly 1 GeV). In this and future works, we aim to calculate the temperature-dependent axion mass at small θ from first-principle lattice calculations, with controlled statistical and systematic errors. Once calculated, this temperature-dependent axion mass is input for the classical evolution equations of the axion density of the Universe, which is required to be less than or equal to the dark matter density. Due to a variety of lattice systematic effects at the very high temperatures required, we perform a calculation of the leading small-θ cumulant of the theta vacua on large volume lattices for SU(3) Yang-Mills with high statistics as a first proof of concept, before attempting a full QCD calculation in the future. From these pure glue results, the misalignment mechanism yields the axion mass bound ma≥(14.6 ±0.1 ) μ eV when Peccei-Quinn breaking occurs

  20. Dynamical axion string, screw dislocation in Weyl semimetals and Axion insulators

    NASA Astrophysics Data System (ADS)

    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.

  1. Response properties of axion insulators and Weyl semimetals driven by screw dislocations and dynamical axion strings

    NASA Astrophysics Data System (ADS)

    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.

  2. Axions and the strong CP problem

    SciTech Connect

    Kim, Jihn E.; Carosi, Gianpaolo

    2010-01-15

    Current upper bounds on the neutron electric dipole moment constrain the physically observable quantum chromodynamic (QCD) vacuum angle |{theta}|(less-or-similar sign)10{sup -11}. Since QCD explains a great deal of experimental data from the 100 MeV to the TeV scale, it is desirable to explain this smallness of |{theta}| in the QCD framework; this is the strong CP problem. There now exist two plausible solutions to this problem, one of which leads to the existence of a very light axion. The axion decay constant window, 10{sup 9}(less-or-similar sign)F{sub a}(less-or-similar sign)10{sup 12} GeV for an O(1) initial misalignment angle {theta}{sub 1}, has been obtained from astrophysical and cosmological data. For F{sub a}(greater-or-similar sign)10{sup 12} GeV with {theta}{sub 1}axions may constitute a significant fraction of the dark matter of the universe. The supersymmetrized axion solution of the strong CP problem introduces its superpartner the axino, which might have affected the evolution of the Universe significantly. The very light axion (theory, supersymmetrization, and models) using recent particle, astrophysical, and cosmological data, and present prospects for its discovery is reviewed here.

  3. Coupled Boltzmann computation of mixed axion neutralino dark matter in the SUSY DFSZ axion model

    NASA Astrophysics Data System (ADS)

    Bae, Kyu Jung; Baer, Howard; Lessa, Andre; Serce, Hasan

    2014-10-01

    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 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 falesssim 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.

  4. Resonance detection of dark matter axions using a DC SQUID

    NASA Astrophysics Data System (ADS)

    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.

  5. Bose-Einstein Condensation of Dark Matter Axions

    SciTech Connect

    Sikivie, P.; Yang, Q.

    2009-09-11

    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.

  6. Solitonic axion condensates modeling dark matter halos

    SciTech Connect

    Castañeda Valle, David Mielke, Eckehard W.

    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.

  7. Axion cold dark matter in nonstandard cosmologies

    SciTech Connect

    Visinelli, Luca; Gondolo, Paolo

    2010-03-15

    We study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these nonstandard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before big bang nucleosynthesis.

  8. Isocurvature forecast in the anthropic axion window

    SciTech Connect

    Hamann, J.; Hannestad, S.; Raffelt, G.G.; Wong, Y.Y.Y. E-mail: sth@phys.au.dk E-mail: yvonne.wong@cern.ch

    2009-06-01

    We explore the cosmological sensitivity to the amplitude of isocurvature fluctuations that would be caused by axions in the ''anthropic window'' where the axion decay constant f{sub a} >> 10{sup 12} GeV and the initial misalignment angle Θ{sub i} << 1. In a minimal ΛCDM cosmology extended with subdominant scale-invariant isocurvature fluctuations, existing data constrain the isocurvature fraction to α < 0.09 at 95% C.L. If no signal shows up, Planck can improve this constraint to 0.042 while an ultimate CMB probe limited only by cosmic variance in both temperature and E-polarisation can reach 0.017, about a factor of five better than the current limit. In the parameter space of f{sub a} and H{sub I} (Hubble parameter during inflation) we identify a small region where axion detection remains within the reach of realistic cosmological probes.

  9. Discrete Abelian gauge symmetries and axions

    NASA Astrophysics Data System (ADS)

    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.

  10. Self-gravitating system made of axions

    SciTech Connect

    Barranco, J.; Bernal, A.

    2011-02-15

    We show that the inclusion of an axionlike effective potential in the construction of a self-gravitating system of scalar fields decreases its compactness when the value of the self-interaction coupling constant is increased. By including the current values for the axion mass m and decay constant f{sub a}, we have computed the mass and the radius for self-gravitating systems made of axion particles. It is found that such objects will have asteroid size masses and radii of a few meters, thus a self-gravitating system made of axions could play the role of scalar mini-MACHOs and mimic a cold dark matter model for the galactic halo.

  11. Detecting Solar Axions Using Earth's Magnetic Field

    SciTech Connect

    Davoudiasl, Hooman; Huber, Patrick

    2006-10-06

    We show that solar axion conversion to photons in the Earth's magnetosphere can produce an x-ray flux, with average energy <{omega}>{approx_equal}4 keV, which is measurable on the dark side of the Earth. The smallness of the Earth's magnetic field is compensated by a large magnetized volume. For axion masses m{sub a}(less-or-similar sign)10{sup -4} eV, a low-Earth-orbit x-ray detector with an effective area of 10{sup 4} cm{sup 2}, pointed at the solar core, can probe the photon-axion coupling down to 10{sup -11} GeV{sup -1}, in 1 yr. Thus, the sensitivity of this new approach will be an order of magnitude beyond current laboratory limits.

  12. Axions as quintessence in string theory

    SciTech Connect

    Panda, Sudhakar; Sumitomo, Yoske; Trivedi, Sandip P.

    2011-04-15

    We construct a model of quintessence in string theory based on the idea of axion monodromy as discussed by McAllister, Silverstein and Westphal [L. McAllister, E. Silverstein, and A. Westphal, Phys. Rev. D 82, 046003 (2010)]. In the model, the quintessence field is an axion whose shift symmetry is broken by the presence of 5-branes which are placed in highly warped throats. This gives rise to a potential for the axion field which is slowly varying, even after incorporating the effects of moduli stabilization and supersymmetry breaking. We find that the resulting time dependence in the equation of state of dark energy is potentially detectable, depending on the initial conditions. The model has many very light extra particles which live in the highly warped throats, but these are hard to detect. A signal in the rotation of the CMB polarization can also possibly arise.

  13. New results in searching for axions by astronomical methods

    NASA Astrophysics Data System (ADS)

    Gnedin, Yu. N.; Piotrovich, M. Yu.

    2016-01-01

    We discuss the astronomical methods of searching for light Goldstone bosons (axions and arions). The basic idea is to use processes of coupling between axions and photons: a) the axion decay into two photons; b) the transformation process of photons into axions (arions) in the magnetic fields of stars and also of interstellar and intergalactic media; c) the inverse process of transformations of axions (arions) which are generated into cores of stars into X-ray photons. The decaying axions affect upon the diffuse extragalactic background radiation, the brightness of the night sky and especially on the intergalactic light of clusters of galaxies due to generation of the axion radiative decay emission line. The processes (b) and (c) are strongly dependent on polarization state of photon and may produce a noticeable amount of linear polarization.

  14. CAST constraints on the axion-electron coupling

    DOE PAGESBeta

    None, None

    2013-05-09

    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 gae and axion-photon interaction strength gaγ using the CAST phase-I data (vacuum phase). For ma ≲ 10 meV/c2 we find gaγ gae < 8.1 × 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 stellarmore » energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission.« less

  15. Cosmological perturbations of axion with a dynamical decay constant

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takeshi; Takahashi, Fuminobu

    2016-08-01

    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.

  16. Axion dark matter and cosmological parameters.

    PubMed

    Erken, O; Sikivie, P; Tam, H; Yang, Q

    2012-02-10

    We observe that photon cooling after big bang nucleosynthesis but before recombination can remove the conflict between the observed and theoretically predicted value of the primordial abundance of ^{7}Li. Such cooling is ordinarily difficult to achieve. However, the recent realization that dark matter axions form a Bose-Einstein condensate provides a possible mechanism because the much colder axions may reach thermal contact with the photons. This proposal predicts a high effective number of neutrinos as measured by the cosmic microwave anisotropy spectrum. PMID:22401054

  17. Axion decay constants away from the lamppost

    NASA Astrophysics Data System (ADS)

    Conlon, Joseph P.; Krippendorf, Sven

    2016-04-01

    It is unknown whether a bound on axion field ranges exists within quantum gravity. We study axion field ranges using extended supersymmetry, in particular allowing an analysis within strongly coupled regions of moduli space. We apply this strategy to Calabi-Yau compactifications with one and two Kähler moduli. We relate the maximally allowable decay constant to geometric properties of the underlying Calabi-Yau geometry. In all examples we find a maximal field range close to the reduced Planck mass (with the largest field range being 3.25 M P ). On this perspective, field ranges relate to the intersection and instanton numbers of the underlying Calabi-Yau geometry.

  18. The pooltable analogy to axion physics

    SciTech Connect

    Sikivie, P.

    1996-01-01

    An imaginary character named TSP finds himself in a playroom whose floor is tilted to one side. However, the pooltable in the playroom is horizontal. TSP wonders how this can be. In doing so, he embarks upon an intellectual journey which parallels that which has been travelled during the past two decades by physicists interested in the Strong CP Problem and axion physics.

  19. The cern axion solar telescope (CAST)

    SciTech Connect

    Aalseth, C. E.; Arik, E.; Autiero, D.; Avignone, F. T.; Barth, K.; Bowyer, S. M.; Brauninger, H.; Brodzinski, R. L.; Carmona, J. M.; Cebrian, S.; Celebi, G.; Cetin, S.; Collar, J. I.; Creswick, R.; Delbart, A.; Delattre, M.; DiLella, L.; De Oliveira, R.; Eleftheriadis, Ch.; Erdutan, N.; Fanourakis, G.; Farach, H. A.; Fiorini, C.; Geralis, Th.; Giomataris, I.; Girard, T. A.; Gninenko, S. N.; Golubev, N. A.; Hasinoff, M.; Hoffmann, D.; Irastorza, I. G.; Jacoby, J.; Jeanneau, F.; Knopf, M. A.; Kovzelev, A. V.; Kotthaus, R.; Krčmar, M.; Krečak, Z.; Lakić, B.; Liolios, A.; Ljubičić, A.; Lutz, G.; Longoni, A.; Luzon, 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.; Sampieto, M.; Sarsa, M.; Savvidis, I.; Stipčević, M.; Thomas, C. W.; Thompson, R. C.; Valco, P.; Villar, J. A.; Villierme, B.; Walckiers, L.; Wilcox, W.; Zachariadou, K.; Zioutas, K.

    2002-07-01

    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 plus or minus 8 to the sixth power vertically and plus or minus 45 to the sixth power, horizontally.

  20. In search of the cleansing axion

    SciTech Connect

    Watson, A.

    1997-04-11

    Physicists` description of nature`s fundamental particles and forces (the Standard Model) may be clarified by the axion, which also could solve the mystery of the universe`s missing mass. However, it must be discovered first. This article summarizes both the optimism and the sceptic view points, along with recent experiments which could add information or fuel to the fire.

  1. Axion hot dark matter bounds after Planck

    SciTech Connect

    Archidiacono, Maria; Hannestad, Steen; Mirizzi, Alessandro; Raffelt, Georg; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk E-mail: raffelt@mpp.mpg.de

    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.

  2. Observational evidence for axion(-like) particles

    NASA Astrophysics Data System (ADS)

    DiLella, L.; Zioutas, K.

    2002-04-01

    Several unexpected astrophysical observations can be explained by gravitationally captured massive axions or axion-like particles produced inside the Sun or other stars. Their radiative decay in solar outer space would give rise to a `self-irradiation' of the whole star, providing the missing corona heating source. In analogy with the Sun-irradiated Earth atmosphere, the temperature and density gradient in the corona/-chromosphere transition region is suggestive for an omnipresent irradiation of the Sun, which is the strongest evidence for the generic axion-like scenario. The radiative decay of a population of such elusive particles mimics a hot gas. The recently reconstructed quiet solar X-ray spectrum supports this work, since it covers the expected energy range, and it is consistent with the result of a simulation based on Kaluza-Klein axions above /~1 keV. At lower energies, using also a ROSAT observation, only /~3% of the solar X-ray intensity is explained. Data from orbiting X-ray Telescopes provide upper limits for particle decay rates 1 AU from the Sun, and suggest new types of searches on Earth or in space. In particular, X-ray observatories, with an unrivalled equivalent fiducial volume of ~103 m3 for the 0.1-10 keV range, can search for the radiative decay of new particles even from existing data.

  3. Axion models with high scale inflation

    NASA Astrophysics Data System (ADS)

    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.

  4. Cavity Microwave Searches for Cosmological Axions

    SciTech Connect

    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.

  5. Review of dark-matter axion experiments

    SciTech Connect

    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.

  6. Constraints on the axion-electron coupling for solar axions produced by a Compton process and bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Derbin, A. V.; Kayunov, A. S.; Muratova, V. V.; Semenov, D. A.; Unzhakov, E. V.

    2011-01-01

    The search for solar axions produced by Compton (γ+e-→e-+A) and bremsstrahlunglike (e-+Z→Z+e-+A) processes has been performed. The axion flux in both cases depends on the axion-electron coupling constant. The resonant excitation of the low-lying nuclear level of Tm169 was looked for: A+Tm169→Tm*169→Tm169+γ (8.41 keV). The Si(Li) detector and Tm169 target installed inside the low-background setup were used to detect 8.41 keV γ rays. As a result, a new model-independent restriction on the axion-electron and the axion-nucleon couplings was obtained: gAe×|gAN0+gAN3|≤2.1×10-14. In the model of the hadronic axion this restriction corresponds to the upper limit on the axion-electron coupling and on the axion mass gAe×mA≤3.1×10-7eV (90% C.L.). The limits on the axion mass are mA≤105eV and mA≤1.3keV for the Dine-Fischler-Srednicki-Zhitnitskii- and Kim-Shifman-Vainstein-Zakharov-axion models, correspondingly (90% C.L.).

  7. Dynamical Axion Field in a Magnetic Topological Insulator Superlattice

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    We propose that the dynamical axion field can be realized in a magnetic topological insulator superlattice or a topological paramagnetic insulator. The magnetic fluctuations of these systems produce a pseudoscalar field which has an axionic coupling to the electromagnetic field, and thus it gives a condensed-matter realization of the axion electrodynamics. Compared to the previously proposed dynamical axion materials where a long range antiferromagnetic order is required, the systems proposed here have the advantage that only an uniform magnetization or a paramagnetic state is needed for the dynamic axion. We further propose several experiments to detect such a dynamical axion field. This work is supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515.

  8. The evolution of structure in the universe from axions

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Shafi, Q.

    1982-01-01

    A scenario where axions provide the dark matter in the universe is considered. Fluctuations in the axion field density produced by domain walls and strings cause the appearance of axion clumps of masses of order 10 to the 6th power solar mass which most likely collapse to black holes by or at the time that the universe becomes axion dominated at T is approximately 10 eV. These objects form the building blocks for a clustering hierarchy theory of galaxy and supercluster formation on scales up to approximately 10 Mpc and approximately 10 to the 15th power solar mass.

  9. Axions and the evolution of structure in the universe

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Shafi, Q.

    1983-01-01

    A cosmological scenario where axions provide the dark matter in the universe is considered. Fluctuations in the axion-field energy denisty produced by domain walls and strings cause the appearance of 'axion clumps' of masses of order 10 to the 6th solar masses which most likely collapse to black holes by or at the time that the universe becomes axion dominated at T approximately 10 eV. These objects form the building blocks for the clustering hierarchy theory of galaxy and supercluster formation on scales up to about 10 Mpc and 10 to the 15th solar masses.

  10. On the possibility of large axion moduli spaces

    SciTech Connect

    Rudelius, Tom

    2015-04-28

    We study the diameters of axion moduli spaces, focusing primarily on type IIB compactifications on Calabi-Yau three-folds. In this case, we derive a stringent bound on the diameter in the large volume region of parameter space for Calabi-Yaus with simplicial Kähler cone. This bound can be violated by Calabi-Yaus with non-simplicial Kähler cones, but additional contributions are introduced to the effective action which can restrict the field range accessible to the axions. We perform a statistical analysis of simulated moduli spaces, finding in all cases that these additional contributions restrict the diameter so that these moduli spaces are no more likely to yield successful inflation than those with simplicial Kähler cone or with far fewer axions. Further heuristic arguments for axions in other corners of the duality web suggest that the difficulty observed in http://dx.doi.org/10.1088/1475-7516/2003/06/001 of finding an axion decay constant parametrically larger than M{sub p} applies not only to individual axions, but to the diagonals of axion moduli space as well. This observation is shown to follow from the weak gravity conjecture of http://dx.doi.org/10.1088/1126-6708/2007/06/060, so it likely applies not only to axions in string theory, but also to axions in any consistent theory of quantum gravity.

  11. Limits to the radiative decay of the axion

    NASA Technical Reports Server (NTRS)

    Ressell, M. Ted

    1991-01-01

    An axion with a mass greater than 1 eV should be detectable through its decay into two photons. The astrophysical and cosmological limits which define a small window of allowed axion mass above 3 eV are discussed. A firm upper bound to the axion's mass of M(sub a) less than or equal to 8 eV is derived by considering the effect of decaying axions upon the diffuse extragalactic background radiation and the brightness of the night sky due to axions in the halo of the Milky Way galaxy. The intergalactic light of clusters of galaxies is shown to be an ideal place to search for an emission line arising from the radiative decay of axions. An unsuccessful search for this emission line in three clusters of galaxies is then detailed. Limits to the presence of any intracluster line emission are derived with the result that axions with masses between 3 and 8 eV are excluded by the data, effectively closing this window of axion mass, unless a severe cancellation of axionic decay amplitudes occurs. The intracluster flux limits are then used to constrain the amplitude of any such model dependence.

  12. Axion cold dark matter in view of BICEP2 results.

    PubMed

    Gondolo, Paolo; Visinelli, Luca

    2014-07-01

    The properties of axions that constitute 100% of cold dark matter (CDM) depend on the tensor-to-scalar ratio r at the end of inflation. If r=0.20(-0.05)(+0.07) as reported by the BICEP2 Collaboration, then "half" of the CDM axion parameter space is ruled out. Namely, in the context of single-field slow-roll inflation, for axions to be 100% of the CDM, the Peccei-Quinn symmetry must be broken after the end of inflation, so that axion nonadiabatic primordial fluctuations are compatible with observational constraints. The cosmic axion density is then independent of the tensor-to-scalar ratio r, and the axion mass is expected to be in a narrow range that, however, depends on the cosmological model before primordial nucleosynthesis. In the standard Lambda CDM cosmology, the CDM axion mass range is ma=(71±2  μeV)(αdec+1)6/7, where αdec is the fractional contribution to the cosmic axion density from decays of axionic strings and walls. PMID:25032919

  13. New solar axion search using the CERN Axion Solar Telescope with 4He filling

    NASA Astrophysics Data System (ADS)

    Arik, M.; Aune, S.; Barth, K.; Belov, A.; Bräuninger, H.; Bremer, J.; Burwitz, V.; Cantatore, G.; Carmona, J. M.; Cetin, S. A.; Collar, J. I.; Da Riva, E.; Dafni, T.; Davenport, M.; Dermenev, A.; Eleftheriadis, C.; Elias, N.; Fanourakis, G.; Ferrer-Ribas, E.; Galán, J.; García, J. A.; Gardikiotis, A.; Garza, J. G.; Gazis, E. N.; Geralis, T.; Georgiopoulou, E.; Giomataris, I.; Gninenko, S.; Gómez Marzoa, M.; Hasinoff, M. D.; Hoffmann, D. H. H.; Iguaz, F. J.; Irastorza, I. G.; Jacoby, J.; Jakovčić, K.; Karuza, M.; Kavuk, M.; Krčmar, M.; Kuster, M.; Lakić, B.; Laurent, J. M.; Liolios, A.; Ljubičić, A.; Luzón, G.; Neff, S.; Niinikoski, T.; Nordt, A.; Ortega, I.; Papaevangelou, T.; Pivovaroff, M. J.; Raffelt, G.; Rodríguez, A.; Rosu, M.; Ruz, J.; Savvidis, I.; Shilon, I.; Solanki, S. K.; Stewart, L.; Tomás, A.; Vafeiadis, T.; Villar, J.; Vogel, J. K.; Yildiz, S. C.; Zioutas, K.; CAST Collaboration

    2015-07-01

    The CERN Axion Solar Telescope (CAST) searches for a →γ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the x-ray refractive mass mγ to the axion search mass ma. After the vacuum phase (2003-2004), which is optimal for ma≲0.02 eV , we used 4He in 2005-2007 to cover the mass range of 0.02-0.39 eV and 3He in 2009-2011 to scan from 0.39 to 1.17 eV. After improving the detectors and shielding, we returned to 4He in 2012 to investigate a narrow ma range around 0.2 eV ("candidate setting" of our earlier search) and 0.39-0.42 eV, the upper axion mass range reachable with 4He, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to ga γ<1.47 ×10-10 GeV-1 (95% C.L.), depending on the pressure settings. Since 2013, we have returned to the vacuum and aim for a significant increase in sensitivity.

  14. Minimal models for axion and neutrino

    NASA Astrophysics Data System (ADS)

    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.

  15. Large volume axionic Swiss cheese inflation

    NASA Astrophysics Data System (ADS)

    Misra, Aalok; Shukla, Pramod

    2008-09-01

    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 Kähler 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 Kähler 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.

  16. Supersymmetry and Cosmology: Inflation, gravitino and axion

    SciTech Connect

    Kawasaki, Masahiro

    2008-05-13

    We discuss some cosmological problems in supersymmetry and supergravity. First, we present (chaotic, hybrid and new) inflation models based on supergravity. Then we consider the serious problem due to thermally and non-thermally produced gravitinos and show that it gives severe constraints on the reheating temperature and the inflaton properties. Finally the supersymmetric axion model is studied and it is shown that overproduction of saxions and axinos sets more stringent upper limit on the reheating temperature than overproduction of the gravitinos.

  17. Axion isocurvature fluctuations with extremely blue spectrum

    SciTech Connect

    Kasuya, Shinta; Kawasaki, Masahiro

    2009-07-15

    We construct an axion model for generating isocurvature fluctuations with blue spectrum, n{sub iso}=2-4, which is suggested by recent analyses of admixture of adiabatic and isocurvature perturbations with independent spectral indices, n{sub ad}{ne}n{sub iso}. The distinctive feature of the model is that the spectrum is blue at large scales while scale invariant at small scales. This is naturally realized by the dynamics of the Peccei-Quinn scalar field.

  18. Cosmological properties of a gauged axion

    SciTech Connect

    Coriano, Claudio; Mariano, Antonio; Guzzi, Marco; Lazarides, George

    2010-09-15

    We analyze the most salient cosmological features of axions in extensions of the standard model with a gauged anomalous extra U(1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axionlike interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a nonperturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stueckelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stueckelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U(1)-SU(3) anomalies.

  19. Axion monodromy and the weak gravity conjecture

    NASA Astrophysics Data System (ADS)

    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.

  20. Multiverse dark matter: SUSY or axions

    NASA Astrophysics Data System (ADS)

    D'Eramo, Francesco; Hall, Lawrence J.; Pappadopulo, Duccio

    2014-11-01

    The observed values of the cosmological constant 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 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 , 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 f = (3 - 30) × 1011 GeV, providing strong motivation to develop experimental techniques for probing lower f.

  1. Non-Gaussianity from axionic curvaton

    SciTech Connect

    Kawasaki, Masahiro; Kobayashi, Takeshi; Takahashi, Fuminobu E-mail: takeshi@cita.utoronto.ca

    2013-03-01

    We study non-Gaussianity of density perturbations generated by an axionic curvaton, focusing on the case that the curvaton sits near the hilltop of the potential during inflation. Such hilltop curvatons can generate a red-tilted density perturbation spectrum without invoking large-field inflation. We show that, even when the curvaton dominates the Universe, the non-Gaussianity parameter f{sub NL} is positive and mildly increases towards the hilltop of the curvaton potential, and that f{sub NL} = O(10) is a general and robust prediction of such hilltop axionic curvatons. In particular, we find that the non-Gaussianity parameter is bounded as f{sub NL}∼<30–40 for a range of the scalar spectral index, n{sub s} = 0.94–0.99, and that f{sub NL} = 20–40 is realized for the curvaton mass m{sub σ} = 10–10{sup 6} GeV and the decay constant f = 10{sup 12}–10{sup 17} GeV. One of the plausible candidates for the axionic curvaton is an imaginary component of a modulus field with mass of order 10–100 TeV and decay constant of 10{sup 16–17}GeV. We also discuss extreme cases where the curvaton drives a second inflation and find that f{sub NL} is typically smaller compared to non-inflating cases.

  2. Cosmological problems with multiple axion-like fields

    NASA Astrophysics Data System (ADS)

    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.

  3. Search For Hadronic Axions Emitted From The Sun

    SciTech Connect

    Ljubicic, A.; Kekez, D.; Krecak, Z.

    2007-10-26

    We made a search for hadronic axions, which could be emitted from the Sun in the axiobremsstrahlung process and absorbed in the HPGe detector by axioelectric effect. An upper limit on hadronic axion mass of 100 eV is obtained at the 95% confidence level.

  4. 3D lumped LC resonators as low mass axion haloscopes

    NASA Astrophysics Data System (ADS)

    McAllister, Ben T.; Parker, Stephen R.; Tobar, Michael E.

    2016-08-01

    The axion is a hypothetical particle considered to be the most economical solution to the strong C P problem. It can also be formulated as a compelling component of dark matter. The haloscope, a leading axion detection scheme, relies on the conversion of galactic halo axions into real photons inside a resonant cavity structure in the presence of a static magnetic field, where the generated photon frequency corresponds to the mass of the axion. For maximum sensitivity it is key that the central frequency of the cavity mode structure coincides with the frequency of the generated photon. As the mass of the axion is unknown, it is necessary to perform searches over a wide range of frequencies. Currently there are substantial regions of the promising preinflationary low-mass axion range without any viable proposals for experimental searches. We show that three-dimensional resonant LC circuits with separated magnetic and electric fields, commonly known as reentrant cavities, can be sensitive dark matter haloscopes in this region, with frequencies inherently lower than those achievable in the equivalent size of empty resonant cavity. We calculate the sensitivity and accessible axion mass range of these experiments, designing geometries to exploit and maximize the separated magnetic and electric coupling of the axion to the cavity mode.

  5. Probing a QCD String Axion with Precision Cosmological Measurements

    SciTech Connect

    Fox, P

    2004-09-21

    String and M-theory compactifications generically have compact moduli which can potentially act as the QCD axion. However, as demonstrated here, such a compact modulus can not play the role of a QCD axion and solve the strong CP problem if gravitational waves interpreted as arising from inflation with Hubble constant H{sub inf} {approx}> 10{sup 13} GeV are observed by the PLANCK polarimetry experiment. In this case axion fluctuations generated during inflation would leave a measurable isocurvature and/or non-Gaussian imprint in the spectrum of primordial temperature fluctuations. This conclusion is independent of any assumptions about the initial axion misalignment angle, how much of the dark matter is relic axions, or possible entropy release by a late decaying particle such as the saxion; it relies only on the mild assumption that the Peccei-Quinn symmetry remains unbroken in the early universe.

  6. Possible resonance effect of axionic dark matter in Josephson junctions.

    PubMed

    Beck, Christian

    2013-12-01

    We provide theoretical arguments that dark-matter axions from the galactic halo that pass through Earth may generate a small observable signal in resonant S/N/S Josephson junctions. The corresponding interaction process is based on the uniqueness of the gauge-invariant axion Josephson phase angle modulo 2π and is predicted to produce a small Shapiro steplike feature without externally applied microwave radiation when the Josephson frequency resonates with the axion mass. A resonance signal of so far unknown origin observed by C. Hoffmann et al. [Phys. Rev. B 70, 180503(R) (2004)] is consistent with our theory and can be interpreted in terms of an axion mass m(a)c2=0.11  meV and a local galactic axionic dark-matter density of 0.05  GeV/cm3. We discuss future experimental checks to confirm the dark-matter nature of the observed signal. PMID:24476255

  7. Searching for low mass axions with an LC-circuit

    NASA Astrophysics Data System (ADS)

    Crisosto, N.; Sikivie, P.; Sullivan, N. S.; Tanner, D. B.; ADMX Collaboration

    2016-03-01

    Axions are a promising cold dark matter candidate. Axion haloscopes such as ADMX, which use the conversion of axions to photons in the presence of a magnetic field, are used to search for axions which decay into microwave photons. To search for lighter, low frequency axions in the unexplored sub 107 eV (50 MHz) range a tunable LC circuit has been proposed. Progress in the development of such an LC circuit based search will be presented. The use of both electrical and mechanical tuning mechanisms will be included. Supported by DOE Grants DE-SC0010280, DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, and the Livermore LDRD program.

  8. Domain wall and isocurvature perturbation problems in axion models

    NASA Astrophysics Data System (ADS)

    Kawasaki, Masahiro; Yanagida, Tsutomu T.; Yoshino, Kazuyoshi

    2013-11-01

    Axion models have two serious cosmological problems, domain wall and isocurvature perturbation problems. In order to solve these problems we investigate the Linde's model in which the field value of the Peccei-Quinn (PQ) scalar is large during inflation. In this model the fluctuations of the PQ field grow after inflation through the parametric resonance and stable axionic strings may be produced, which results in the domain wall problem. We study formation of axionic strings using lattice simulations. It is found that in chaotic inflation the axion model is free from both the domain wall and the isocurvature perturbation problems if the initial misalignment angle θa is smaller than O(10-2). Furthermore, axions can also account for the dark matter for the breaking scale v simeq 1012-16 GeV and the Hubble parameter during inflation Hinflesssim1011-12 GeV in general inflation models.

  9. Search for axioelectric effect of solar axions using BGO scintillating bolometer

    NASA Astrophysics Data System (ADS)

    Derbin, A. V.; Gironi, L.; Nagorny, S. S.; Pattavina, L.; Beeman, J. W.; Bellini, F.; Biassoni, M.; Capelli, S.; Clemenza, M.; Drachnev, I. S.; Ferri, E.; Giachero, A.; Gotti, C.; Kayunov, A. S.; Maiano, C.; Maino, M.; Muratova, V. N.; Pavan, M.; Pirro, S.; Semenov, D. A.; Sisti, M.; Unzhakov, E. V.

    2014-09-01

    A search for axioelectric absorption of solar axions produced in the reaction has been performed with a BGO detector placed in a low-background setup. A model-independent limit on the combination of axion-nucleon and axion-electron coupling constants has been obtained: for 90 % confidence level. The constraint of the axion-electron coupling constant has been obtained for hadronic axion with masses of (0.1-1) MeV:.

  10. Constraints on the axion-electron coupling for solar axions produced by a Compton process and bremsstrahlung

    SciTech Connect

    Derbin, A. V.; Kayunov, A. S.; Muratova, V. V.; Semenov, D. A.; Unzhakov, E. V.

    2011-01-15

    The search for solar axions produced by Compton ({gamma}+e{sup -}{yields}e{sup -}+A) and bremsstrahlunglike (e{sup -}+Z{yields}Z+e{sup -}+A) processes has been performed. The axion flux in both cases depends on the axion-electron coupling constant. The resonant excitation of the low-lying nuclear level of {sup 169}Tm was looked for: A+{sup 169}Tm{yields}{sup 169}Tm{sup *}{yields}{sup 169}Tm+{gamma} (8.41 keV). The Si(Li) detector and {sup 169}Tm target installed inside the low-background setup were used to detect 8.41 keV {gamma} rays. As a result, a new model-independent restriction on the axion-electron and the axion-nucleon couplings was obtained: g{sub Ae}x|g{sub AN}{sup 0}+g{sub AN}{sup 3}|{<=}2.1x10{sup -14}. In the model of the hadronic axion this restriction corresponds to the upper limit on the axion-electron coupling and on the axion mass g{sub Ae}xm{sub A{<=}}3.1x10{sup -7} eV (90% C.L.). The limits on the axion mass are m{sub A{<=}}105 eV and m{sub A{<=}}1.3 keV for the Dine-Fischler-Srednicki-Zhitnitskii- and Kim-Shifman-Vainstein-Zakharov-axion models, correspondingly (90% C.L.).

  11. Solitonic axion condensates modeling dark matter halos

    NASA Astrophysics Data System (ADS)

    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.

  12. CAST constraints on the axion-electron coupling

    SciTech Connect

    Barth, K.; Davenport, M.; Lella, L. Di; Belov, A.; Beltran, B.; Carmona, J.M.; Dafni, T.; Galan, J.; García, J.A.; Braeuninger, H.; Englhauser, J.; Friedrich, P.; Collar, J.I.; Eleftheriadis, C.; Fanourakis, G.; Geralis, T.; Ferrer-Ribas, E.; Giomataris, I.; Fischer, H.; Franz, J. E-mail: Julia.Vogel@cern.ch; 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.

  13. CAST constraints on the axion-electron coupling

    SciTech Connect

    None, None

    2013-05-09

    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 gae and axion-photon interaction strength g using the CAST phase-I data (vacuum phase). For ma ≲ 10 meV/c2 we find gaγ gae < 8.1 × 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.

  14. Axion searches with the EDELWEISS-II experiment

    SciTech Connect

    Armengaud, E.; Boissière, T. de; Arnaud, Q.; Augier, C.; Benoit, A.; Cazes, A.; Censier, B.; Charlieux, F.; Jesus, M. De; Bergé, L.; Broniatowski, A.; Chapellier, M.; Couëdo, F.; Bergmann, T.; Blümer, J.; Cox, G.A.; Brudanin, V.; Coulter, P. E-mail: thibault.main-de-boissiere@cea.fr; and others

    2013-11-01

    We present new constraints on the couplings of axions and more generic axion-like particles using data from the EDELWEISS-II experiment. The EDELWEISS experiment, located at the Underground Laboratory of Modane, primarily aims at the direct detection of WIMPs using germanium bolometers. It is also sensitive to the low-energy electron recoils that would be induced by solar or dark matter axions. Using a total exposure of up to 448 kg.d, we searched for axion-induced electron recoils down to 2.5 keV within four scenarios involving different hypotheses on the origin and couplings of axions. We set a 95 % CL limit on the coupling to photons g{sub Aγ} < 2.15 × 10{sup −9} GeV{sup −1} in a mass range not fully covered by axion helioscopes. We also constrain the coupling to electrons, g{sub Ae} < 2.59 × 10{sup −11}, similar to the more indirect solar neutrino bound. Finally we place a limit on g{sub Ae} × g{sub AN}{sup eff} < 4.82 × 10{sup −17}, where g{sub AN}{sup eff} is the effective axion-nucleon coupling for {sup 57}Fe. Combining these results we fully exclude the mass range 0.92 eV < m{sub A} < 80 keV for DFSZ axions and 5.78 eV < m{sub A} < 40 keV for KSVZ axions.

  15. The cern axion solar telescope (CAST): an update

    NASA Astrophysics Data System (ADS)

    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.

  16. Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas.

    PubMed

    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

  17. Vacuum statistics and stability in axionic landscapes

    NASA Astrophysics Data System (ADS)

    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.

  18. Cosmic axion background propagation in galaxies

    NASA Astrophysics Data System (ADS)

    Day, Francesca V.

    2016-02-01

    Many extensions of the Standard Model include axions or axion-like particles (ALPs). Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB) analogous to the CMB, whose existence is suggested by string models of inflation. ALP-photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP-photon conversion in the Milky Way would be unobservably small. The ALP-photon conversion probability in galaxy clusters is 3 orders of magnitude higher than that in the Milky Way. Furthermore, the morphology of the unresolved cosmic X-ray background is incompatible with a significant component from ALP-photon conversion. We also consider ALP-photon conversion in starburst galaxies, which host much higher magnetic fields. By considering the clumpy structure of the galactic plasma, we find that conversion probabilities comparable to those in clusters may be possible in starburst galaxies.

  19. Periodic signatures for the detection of cosmic axions

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1990-01-01

    In a Sikivie-type cosmic-axion detector, both the width and position of the microwave signal due to axion-photon conversion depend upon the motions of the earth. Due to the orbital and rotational motions of the earth they will be modulated with periods of 1 sidereal day and 1 sidereal year, with amplitudes of about 0.1 percent and 5 percent respectively. Because of the intrinsically-high energy resolution of Sikivie-type detectors such periodic variations should be detectable. Such modulations would not only aid in confirming the detection of cosmic axions, but, if found, would also provide important information about the distribution of axions in the halo.

  20. A dark matter solution from the supersymmetric axion model

    SciTech Connect

    Chang, Sanghyeon; Kim, Hang Bae

    1996-05-01

    We study the effect of the late decaying saxino (the scalar superpartner of the axion) and find out that there is a possible dark matter solution from a class of supersymmetric extensions of the invisible axion model. In this class of models, the saxino which decays into two axions acts as the late decaying particle which reconciles the cold dark matter model with high values of the Hubble constant. Recent observations of the Hubble constant are converging to H{sub 0} = 70--80 km sec{sup {minus}1} Mpc{sup {minus}1}, which would be inconsistent with the standard mixed dark matter model. This class of models provides a plausible framework for the alternative cold dark matter plus late decaying particle model, with the interesting possibility that both cold dark matter and the extra radiation consist of axion. 15 refs.

  1. High-scale axions without isocurvature from inflationary dynamics

    NASA Astrophysics Data System (ADS)

    Kearney, John; Orlofsky, Nicholas; Pierce, Aaron

    2016-05-01

    Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation HI . If the scale of Peccei-Quinn (PQ) breaking fa is greater than H/I 2 π , CMB constraints on isocurvature naively rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation fI require either late-time dilution of the axion abundance or highly super-Planckian fI that somehow does not dominate the inflationary energy density. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow fa close to the Planck scale. Avoiding disruption of inflationary dynamics provides important limits on the parameter space.

  2. The electroweak axion, dark energy, inflation and baryonic matter

    SciTech Connect

    McLerran, L.

    2015-03-15

    In a previous paper [1], the standard model was generalized to include an electroweak axion which carries baryon plus lepton number, B + L. It was shown that such a model naturally gives the observed value of the dark energy, if the scale of explicit baryon number violation A was chosen to be of the order of the Planck mass. In this paper, we consider the effect of the modulus of the axion field. Such a field must condense in order to generate the standard Goldstone boson associated with the phase of the axion field. This condensation breaks baryon number. We argue that this modulus might be associated with inflation. If an additional B − L violating scalar is introduced with a mass similar to that of the modulus of the axion field, we argue that decays of particles associated with this field might generate an acceptable baryon asymmetry.

  3. N-flation with hierarchically light axions in string compactifications

    SciTech Connect

    Cicoli, Michele; Dutta, Koushik

    2014-08-01

    We propose a possible embedding of axionic N-flation in type IIB string compactifications where most of the Kähler moduli are stabilised by perturbative effects, and so are hierarchically heavier than the corresponding N>> 1 axions whose collective dynamics drives inflation. This is achieved in the framework of the LARGE Volume Scenario for moduli stabilisation. Our set-up can be used to realise a model of either large field inflation or quintessence, just by varying the volume of the internal space which controls the scale of the axionic potential. Both cases predict a very high scale of supersymmetry breaking. A fully explicit stringy embedding of N-flation would require control over dangerous back-reaction effects due to a large number of species. A viable reheating of the Standard Model degrees of freedom can be achieved after the end of inflation due to the perturbative decay of the N light axions which drive inflation.

  4. The spectral index and its running in axionic curvaton

    SciTech Connect

    Takahashi, Fuminobu

    2013-06-01

    We show that a sizable running spectral index suggested by the recent SPT data can be explained in the axionic curvaton model with a potential that consists of two sinusoidal contributions of different height and period. We find that the running spectral index is generically given by dn{sub s}/dln k ∼ 2π/ΔN (n{sub s}−1), where ΔN is the e-folds during one period of modulations. In the string axiverse, axions naturally acquire a mass from multiple contributions, and one of the axions may be responsible for the density perturbations with a sizable running spectral index via the curvaton mechanism. We note that the axionic curvaton model with modulations can also accommodate the red-tilted spectrum with a negligible running, without relying on large-field inflation.

  5. Constraints on axion inflation from the weak gravity conjecture

    NASA Astrophysics Data System (ADS)

    Rudelius, Tom

    2015-09-01

    We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and `anti-alignment' of C4 axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the `generalized' weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C4 axions in type IIB compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.

  6. Constraints on axion inflation from the weak gravity conjecture

    SciTech Connect

    Rudelius, Tom

    2015-09-08

    We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and ‘anti-alignment’ of C{sub 4} axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the ‘generalized’ weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C{sub 4} axions in type IIB compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.

  7. Axion cosmology with long-lived domain walls

    SciTech Connect

    Hiramatsu, Takashi; Kawasaki, Masahiro; Saikawa, Ken'ichi; Sekiguchi, Toyokazu E-mail: kawasaki@icrr.u-tokyo.ac.jp E-mail: sekiguti@a.phys.nagoya-u.ac.jp

    2013-01-01

    We investigate the cosmological constraints on axion models where the domain wall number is greater than one. In these models, multiple domain walls attached to strings are formed, and they survive for a long time. Their annihilation occurs due to the effects of explicit symmetry breaking term which might be raised by Planck-scale physics. We perform three-dimensional lattice simulations and compute the spectra of axions and gravitational waves produced by long-lived domain walls. Using the numerical results, we estimated relic density of axions and gravitational waves. We find that the existence of long-lived domain walls leads to the overproduction of cold dark matter axions, while the density of gravitational waves is too small to observe at the present time. Combining the results with other observational constraints, we find that the whole parameter region of models are excluded unless an unacceptable fine-tuning exists.

  8. High-scale axions without isocurvature from inflationary dynamics

    DOE PAGESBeta

    Kearney, John; Orlofsky, Nicholas; Pierce, Aaron

    2016-05-31

    Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation HI. If the scale of Peccei-Quinn (PQ) breaking fa is greater than HI/2π, CMB constraints on isocurvature naively rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation fI require either late-time dilution of the axion abundance or highly super-Planckian fI that somehowmore » does not dominate the inflationary energy density. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow fa close to the Planck scale. Lastly, avoiding disruption of inflationary dynamics provides important limits on the parameter space.« less

  9. New bounds for axions and axion-like particles with keV-GeV masses

    NASA Astrophysics Data System (ADS)

    Millea, Marius; Knox, Lloyd; Fields, Brian D.

    2015-07-01

    We give updated constraints on hypothetical light bosons with a two-photon coupling such as axions or axion-like particles (ALPs). We focus on masses and lifetimes where decays happen near big bang nucleosynthesis (BBN), thus altering the baryon-to-photon ratio and number of relativistic degrees of freedom between the BBN epoch and the cosmic microwave background's (CMB) last scattering epoch, in particular such that NeffCMBaxion arising from a symmetry breaking near the electroweak scale, is now ruled out at >3 σ by the combination of CMB +D /H measurements if only ALPs and three thermalized neutrino species contribute to Neff . The bound relaxes if there are additional light degrees of freedom present which, in this scenario, have their contribution limited to Δ Neff=1.1 ±0.3 . We give forecasts showing that a number of experiments are expected to reach the sensitivity needed to further test this region, such as Stage-IV CMB and SUPER-KEKB, the latter a direct test insensitive to any extra degrees of freedom.

  10. Dark radiation constraints on mixed Axion/Neutralino dark matter

    SciTech Connect

    Bae, Kyu Jung; Baer, Howard; Lessa, Andre E-mail: baer@nhn.ou.edu

    2013-04-01

    Recent analyses of CMB data combined with the measurement of BAO and H{sub 0} show that dark radiation — parametrized by the apparent number of additional neutrinos ΔN{sub eff} contributing to the cosmic expansion — is bounded from above by about ΔN{sub eff}∼<1.6 at 95% CL. We consider the mixed axion/neutralino cold dark matter scenario which arises in R-parity conserving supersymmetric (SUSY) models wherein the strong CP problem is solved by hadronic axions with a concommitant axion(a)/saxion(s)/axino(ã) supermultiplet. Our new results include improved calculations of thermal axion and saxion production and include effects of saxion decay to axinos and axions. We show that the above bound on ΔN{sub eff} is easily satisfied if saxions are mainly thermally produced and m{sub LSP} < m{sub ã}∼axions. Furthermore we show that scenarios with mixed neutralino/axion dark matter are highly constrained by combined CMB, BBN and Xe-100 constraints. In particular, supersymmetric models with a standard overabundance of neutralino dark matter are excluded for all values of the Peccei-Quinn breaking scale. Next generation WIMP direct detection experiments may be able to discover or exclude mixed axion-neutralino CDM scenarios where s → aa is the dominant saxion decay mode.

  11. Towards universal axion inflation and reheating in string theory

    NASA Astrophysics Data System (ADS)

    Blumenhagen, Ralph; Plauschinn, Erik

    2014-09-01

    The recent BICEP2 measurements of B-modes indicate a large tensor-to-scalar ratio in inflationary cosmology, which points towards trans-Planckian evolution of the inflaton. We propose possible string-theory realizations thereof. Schemes for natural and axion monodromy inflation are presented in the framework of the type IIB large volume scenario. The inflaton in both cases is given by the universal axion and its potential is generated by F-terms. Our models are shown to feature a natural mechanism for inflaton decay into predominantly Standard Model particles. We assume that the (flux) landscape admits points where the masses of the saxions (including the dilaton) are hierarchically different from the mass of C0. In particular, apart from the nearly massless axion of the big four-cycle in a LVS, C0 can be the lightest closed-string modulus, making it a good candidate for the inflaton. For natural inflation, the potential of the axion is generated by non-perturbative effects from fluxed E3-instantons, whereas for axion monodromy inflation the axion C0 can appear quadratically in the flux induced scalar potential. There exists a mechanism guaranteeing that inflaton decay at the end of inflation predominantly goes into standard model (SM) degrees of freedom. This last point is one of the very interesting aspects of the models considered in this Letter. Note furthermore that the relevant axion potentials are F-terms in an effective spontaneously-broken supergravity theory, which is in the same spirit as [18].Finally, note that an axion decay constant f>Mpl corresponds to the non-perturbative (F-theory) regime gs>1 of the type IIB superstring. We collect some indications that the LVS scenario might be trustable even for string coupling constants slightly larger than one, but of course conclusive evidence requires the parametric control over infinitely many perturbative corrections to the Kähler potential.

  12. Class of Einstein-Maxwell-dilaton-axion space-times

    SciTech Connect

    Matos, Tonatiuh; Miranda, Galaxia; Sanchez-Sanchez, Ruben; Wiederhold, Petra

    2009-06-15

    We use the harmonic maps ansatz to find exact solutions of the Einstein-Maxwell-dilaton-axion (EMDA) equations. The solutions are harmonic maps invariant to the symplectic real group in four dimensions Sp(4,R){approx}O(5). We find solutions of the EMDA field equations for the one- and two-dimensional subspaces of the symplectic group. Specially, for illustration of the method, we find space-times that generalize the Schwarzschild solution with dilaton, axion, and electromagnetic fields.

  13. Proposal for Axion Dark Matter Detection Using an LC Circuit

    DOE PAGESBeta

    Sikivie, P.; Sullivan, N.; Tanner, D. B.

    2014-03-01

    Here, we show that dark matter axions cause an oscillating electric current to flow along magnetic field lines. The oscillating current induced in a strong magnetic field B→ 0 produces a small magnetic field B→ a. We propose to amplify and detect B→ a using a cooled LC circuit and a very sensitive magnetometer. This appears to be a suitable approach to searching for axion dark matter in the 10–7 to 10–9 eV mass range.

  14. Second-generation dark-matter axion search

    SciTech Connect

    Sikivie, P.; Sullivan, N.S.; Tanner, D.B.

    1996-12-01

    This research project is a collaboration with the axion search experiment at Lawrence Livermore National Laboratory. The axion is a particle that affects two important issues in particle physics and astrophysics: the origin of CP symmetry in the strong interactions, and the composition of the dark-matter of the universe. First predicted in 1978, present laboratory, astrophysical, and cosmological constraints suggest axions have a mass in the 1 {mu}eV-1 meV range. Axions are especially significant as dark matter if their mass is in the range 1-10 {mu}eV. These dark matter axions may be detected by their coupling to photons through the E - B interaction in a tunable high-Q microwave cavity permeated by a strong external magnetic field. The present experiment is the first cavity experiment with the sensitivity to possibly observe cosmic axions. It has recently begun taking data and will operate for the next several years. The University of Florida plans to contribute to the operation of this detector and to the design and prototyping of cavities for the experiment.

  15. Direct detection of dark matter axions with directional sensitivity

    SciTech Connect

    Irastorza, Igor G.; García, Juan A. E-mail: jagarpas@unizar.es

    2012-10-01

    We study the directional effect of the expected axion dark matter signal in a resonant cavity of an axion haloscope detector, for cavity geometries not satisfying the condition that the axion de Broglie wavelength λ{sub a} is sufficiently larger than the cavity dimensions L for a fully coherent conversion, i.e. λ{sub a}∼>2πL. We focus on long thin cavities immersed in dipole magnets and find, for appropriately chosen cavity lengths, an O(1) modulation of the signal with the cavity orientation with respect the momentum distribution of the relic axion background predicted by the isothermal sphere model for the galactic dark matter halo. This effect can be exploited to design directional axion dark matter detectors, providing an unmistakable signature of the extraterrestrial origin of a possible positive detection. Moreover, the precise shape of the modulation may give information of the galactic halo distribution and, for specific halo models, give extra sensitivity for higher axion masses.

  16. Searching for Axion Dark Matter with Atoms and Ultracold Neutrons

    NASA Astrophysics Data System (ADS)

    Stadnik, Yevgeny; Dzuba, Vladimir; Flambaum, Victor; Roberts, Benjamin; Rawlik, Michal; the nEDM collaboration at PSI Collaboration

    2016-05-01

    We propose new schemes to directly search for axion dark matter with atoms and ultracold neutrons. Axions are an excellent candidate for the observed cold dark matter; their low mass and weak-strength interactions with ordinary matter mean that axions can readily form an oscillating classical field that survives to reside in the observed galactic dark matter haloes. The oscillating nature of the axion field gives rise to a number of oscillating effects in atoms and neutrons, which include oscillating electric dipole moments, and the precession of polarised spins about Earth's direction of motion through galactic axions. Importantly, these effects scale as the first power of the underlying interaction constant (whereas traditionally-sought effects of dark matter scale as the second or fourth power). First-power effects may thus provide a very strong advantage, since the interaction constant is extremely small. We present an overview of ongoing efforts of the nEDM collaboration at PSI to search for axion dark matter via these effects using a dual neutron/Hg-199 co-magnetometer.

  17. On the Relaxation of Superstring Axion Mini-Clusters

    NASA Astrophysics Data System (ADS)

    Pollock, M. D.

    The cosmological axion theory leads to the prediction of axionic mini-clusters of mass M 10-9Msolar, which form at the time te of equipartition of matter and radiation. By applying the two-body relaxation formula of Spitzer and Hart, we show, for the heterotic superstring theory of Gross et al., that these mini-clusters, considered as point masses, themselves cluster into axion mini-stars of mass M0≈ 10-2 (1 + λ 2)3/4 g3sMsun within the age of the Universe t0 only if they are located within a distance R 0.1 pc of the Galactic Center. Here, λ ≡ fB/fA is the ratio of the second to model-independent axion decay constants, assuming the QCD decay constant to be in the range 2.18 x 1016 g2s <= fa ≡ (1)/(2)(1+λ 2)1/2 fA/GeV< ˜ 2.4x 1018, and g2s ≈ 1.4 is the strong-interaction coupling parameter. Thus, if axion mini-stars are to explain the microlensing observations by the EROS and MACHO groups towards the Galactic Bulge and the Large and Small Magellanic Clouds, then a collisionless relaxation mechanism is required, as proposed by Seidel and Suen (essentially the violent relaxation of Lynden-Bell), or the four-axion self-interaction effect considered by Tkachev.

  18. Astrophysical hints of axion-like particles

    NASA Astrophysics Data System (ADS)

    Roncadelli, M.; Galanti, G.; Tavecchio, F.; Bonnoli, G.

    2015-01-01

    After reviewing three astrophysical hints of the existence of axion-like particles (ALPs), we describe in more detail a new similar hint involving flat spectrum radio quasars (FSRQs). Detection of FSRQs above about 20GeV pose a challenge to very-high-energy (VHE) astrophysics, because at those energies the ultraviolet emission from their broad line region should prevent photons produced by the central engine to leave the source. Although a few astrophysical explanations have been put forward, they are totally ad hoc. We show that a natural explanation instead arises within the conventional models of FSRQs provided that photon-ALP oscillations occur inside the source. Our analysis takes the FSRQ PKR 1222+206 as an example, and it looks tantalizing that basically the same choice of the free model parameters adopted in this case is consistent with those that provide the other three hints of the existence of ALPs.

  19. Bifid throats for axion monodromy inflation

    NASA Astrophysics Data System (ADS)

    Retolaza, Ander; Uranga, Angel M.; Westphal, Alexander

    2015-07-01

    We construct a simple explicit local geometry providing a `bifid throat' for 5-brane axion monodromy. A bifid throat is a throat that splits into two daughter throats in the IR, containing a homologous 2-cycle family reaching down into each daughter throat. Our example consists of a deformed ℤ 3 × ℤ 2 orbifold of the conifold, which provides us with an explicit holographic dual of the bifid throat including D3-branes and fractional 5-branes at the toric singularities of our setup. Having the holographic description in terms of the dual gauge theory allows us to address the effect of 5-brane-antibrane pair backreaction including the warping effects. This leads to the size of the backreaction being small and controllable after imposing proper normalization of the inflaton potential and hence the warping scales.

  20. GammeV: Fermilab axion-like particle photon regeneration results

    SciTech Connect

    Wester, William; /Fermilab

    2008-09-01

    GammeV is an axion-like particle photon regeneration experiment conducted at Fermilab that employs the light shining through a wall technique. They obtain limits on the coupling of a photon to an axion-like particle that extend previous limits for both scalar and pseudoscalar axion-like particles in the milli-eV mass range. They are able to exclude the axion-like particle interpretation of the anomalous PVLAS 2006 result by more than 5 standard deviations.

  1. Axion cold dark matter: Status after Planck and BICEP2

    NASA Astrophysics Data System (ADS)

    Di Valentino, Eleonora; Giusarma, Elena; Lattanzi, Massimiliano; Melchiorri, Alessandro; Mena, Olga

    2014-08-01

    We investigate the axion dark matter scenario (ADM), in which axions account for all of the dark matter in the Universe, in light of the most recent cosmological data. In particular, we use the Planck temperature data, complemented by WMAP E-polarization measurements, as well as the recent BICEP2 observations of B-modes. Baryon acoustic oscillation data, including those from the baryon oscillation spectroscopic survey, are also considered in the numerical analyses. We find that, in the minimal ADM scenario and for ΛQCD=200 MeV, the full data set implies that the axion mass ma=82.2±1.1 μeV [corresponding to the Peccei-Quinn symmetry being broken at a scale fa=(7.54±0.10)×1010 GeV], or ma=76.6±2.6 μeV [fa=(8.08±0.27)×1010 GeV] when we allow for a nonstandard effective number of relativistic species Neff. We also find a 2σ preference for Neff>3.046. The limit on the sum of neutrino masses is ∑mν<0.25 eV at 95% C.L. for Neff=3.046, or ∑mν<0.47 eV when Neff is a free parameter. Considering extended scenarios where either the dark energy equation-of-state parameter w, the tensor spectral index nt, or the running of the scalar index dns/dlnk is allowed to vary does not change significantly the axion mass-energy density constraints. However, in the case of the full data set exploited here, there is a preference for a nonzero tensor index or scalar running, driven by the different tensor amplitudes implied by the Planck and BICEP2 observations. We also study the effect on our estimates of theoretical uncertainties, in particular the imprecise knowledge of the QCD scale ΛQCD, in the calculation of the temperature-dependent axion mass. We find that in the simplest ADM scenario the Planck +WP data set implies that the axion mass ma=63.7±1.2 μeV for ΛQCD=400 MeV. We also comment on the possibility that axions do not make up for all the dark matter, or that the contribution of string-produced axions has been grossly underestimated; in that case, the values

  2. Axion dark matter, solitons and the cusp-core problem

    NASA Astrophysics Data System (ADS)

    Marsh, David J. E.; Pop, Ana-Roxana

    2015-08-01

    Self-gravitating bosonic fields can support stable and localized (solitonic) field configurations. Such solitons should be ubiquitous in models of axion dark matter, with their characteristic mass and size depending on some inverse power of the axion mass, ma. Using a scaling symmetry and the uncertainty principle, the soliton core size can be related to the central density and axion mass in a universal way. Solitons have a constant central density due to pressure support, unlike the cuspy profile of cold dark matter (CDM). Consequently, solitons composed of ultralight axions (ULAs) may resolve the `cusp-core' problem of CDM. In dark matter (DM) haloes, thermodynamics will lead to a CDM-like Navarro-Frenk-White (NFW) profile at large radii, with a central soliton core at small radii. Using Monte Carlo techniques to explore the possible density profiles of this form, a fit to stellar kinematical data of dwarf spheroidal galaxies is performed. The data favour cores, and show no preference concerning the NFW part of the halo. In order for ULAs to resolve the cusp-core problem (without recourse to baryon feedback, or other astrophysical effects) the axion mass must satisfy ma < 1.1 × 10-22 eV at 95 per cent C.L. However, ULAs with ma ≲ 1 × 10-22 eV are in some tension with cosmological structure formation. An axion solution to the cusp-core problem thus makes novel predictions for future measurements of the epoch of reionization. On the other hand, improved measurements of structure formation could soon impose a Catch 22 on axion/scalar field DM, similar to the case of warm DM.

  3. Weak gravity strongly constrains large-field axion inflation

    NASA Astrophysics Data System (ADS)

    Heidenreich, Ben; Reece, Matthew; Rudelius, Tom

    2015-12-01

    Models of large-field inflation based on axion-like fields with shift symmetries can be simple and natural, and make a promising prediction of detectable primordial gravitational waves. The Weak Gravity Conjecture is known to constrain the simplest case in which a single compact axion descends from a gauge field in an extra dimension. We argue that the Weak Gravity Conjecture also constrains a variety of theories of multiple compact axions including N-flation and some alignment models. We show that other alignment models entail surprising consequences for how the mass spectrum of the theory varies across the axion moduli space, and hence can be excluded if further conjectures hold. In every case that we consider, plausible assumptions lead to field ranges that cannot be parametrically larger than M Pl. Our results are strongly suggestive of a general inconsistency in models of large-field inflation based on compact axions, and possibly of a more general principle forbidding super-Planckian field ranges.

  4. Hunting for axion dark matter with the ADMX project

    NASA Astrophysics Data System (ADS)

    Carosi, Gianpaolo; ADMX Collaboration

    2016-03-01

    The axion is a hypothetical particle that explains why the strong force is CP invariant and could also account for the cold dark matter in the universe. The Axion Dark Matter eXperiment (ADMX) directly searches for dark-matter axions by looking for their resonant conversion into detectable photons in a microwave cavity permeated by a strong magnetic field. This experiment, currently a ``Generation 2'' DOE Dark Matter Project, is now preparing for operations with enough sensitivity to either detect the ``QCD axion'' or reject that hypothesis at high confidence over a large range of potential axion masses. This talk will give an overview of the ADMX project and technology, its search plan and some of the various R&D projects that are being undertaken to extend its sensitivity. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, and the Livermore LDRD program.

  5. Neutrino and axion hot dark matter bounds after WMAP-7

    SciTech Connect

    Hannestad, Steen; Mirizzi, Alessandro; Raffelt, Georg G.; Wong, Yvonne Y.Y. E-mail: alessandro.mirizzi@desy.de E-mail: yvonne.wong@physik.rwth-aachen.de

    2010-08-01

    We update cosmological hot dark matter constraints on neutrinos and hadronic axions. Our most restrictive limits use 7-year data from the Wilkinson Microwave Anisotropy Probe for the cosmic microwave background anisotropies, the halo power spectrum (HPS) from the 7th data release of the Sloan Digital Sky Survey, and the Hubble constant from Hubble Space Telescope observations. We find 95% CL upper limits of Σm{sub ν} < 0.44 eV (no axions), m{sub a} < 0.91 eV (assuming Σm{sub ν} = 0), and Σm{sub ν} < 0.41 eV and m{sub a} < 0.72 eV for two hot dark matter components after marginalising over the respective other mass. CMB data alone yield Σm{sub ν} < 1.19 eV (no axions), while for axions the HPS is crucial for deriving m{sub a} constraints. This difference can be traced to the fact that for a given hot dark matter fraction axions are much more massive than neutrinos.

  6. Domain wall and isocurvature perturbation problems in axion models

    SciTech Connect

    Kawasaki, Masahiro; Yoshino, Kazuyoshi; Yanagida, Tsutomu T. E-mail: tsutomu.tyanagida@ipmu.jp

    2013-11-01

    Axion models have two serious cosmological problems, domain wall and isocurvature perturbation problems. In order to solve these problems we investigate the Linde's model in which the field value of the Peccei-Quinn (PQ) scalar is large during inflation. In this model the fluctuations of the PQ field grow after inflation through the parametric resonance and stable axionic strings may be produced, which results in the domain wall problem. We study formation of axionic strings using lattice simulations. It is found that in chaotic inflation the axion model is free from both the domain wall and the isocurvature perturbation problems if the initial misalignment angle θ{sub a} is smaller than O(10{sup −2}). Furthermore, axions can also account for the dark matter for the breaking scale v ≅ 10{sup 12−16} GeV and the Hubble parameter during inflation H{sub inf}∼<10{sup 11−12} GeV in general inflation models.

  7. Cosmic D-strings as axionic D-term strings

    SciTech Connect

    Blanco-Pillado, Jose J.; Dvali, Gia; Redi, Michele

    2005-11-15

    In this work we derive nonsingular BPS string solutions from an action that captures the essential features of a D-brane-anti-D-brane system compactified to four dimensions. The model we consider is a supersymmetric Abelian Higgs model with a D-term potential coupled to an axion-dilaton multiplet. The strings in question are axionic D-term strings which we identify with the D-strings of type II string theory. In this picture the Higgs field represents the open string tachyon of the D-D pair and the axion is dual to a Ramond-Ramond form. The crucial term allowing the existence of nonsingular BPS strings is the Fayet-Iliopoulos term, which is related to the tensions of the D-string and of the parent branes. Despite the presence of the axion, the strings are BPS and carry finite energy, due to the fact that the space gets very slowly decompactified away from the core, screening the long range axion field (or equivalently the theory approaches an infinitely weak 4D coupling). Within our 4D effective action we also identify another class of BPS string solutions (s-strings) which have no ten-dimensional analog, and can only exist after compactification.

  8. A SQUID-based microwave cavity search for dark-matter axions

    SciTech Connect

    Asztalos, S J; Carosi, G; Hagmann, C; Kinion, D; van Bibber, K; Hotz, M; Rosenberg, L; Rybka, G; Hoskins, J; Hwang, J; Sikivie, P; Tanner, D B; Bradley, R; Clarke, J

    2009-10-21

    Axions in the {mu}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. The first result from such an axion search using a superconducting first-stage amplifier (SQUID) is reported. The SQUID amplifier, replacing a conventional GaAs field-effect transistor amplifier, successfully reached axion-photon coupling sensitivity in the band set by present axion models and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.

  9. Cosmological bounds on sub-MeV mass axions

    SciTech Connect

    Cadamuro, Davide; Raffelt, Georg; Redondo, Javier; Hannestad, Steen E-mail: sth@phys.au.dk E-mail: redondo@mppmu.mpg.de

    2011-02-01

    Axions with mass m{sub a} ∼> 0.7 eV are excluded by cosmological precision data because they provide too much hot dark matter. While for m{sub a} ∼> 20 eV the a → 2γ lifetime drops below the age of the universe, we show that the cosmological exclusion range can be extended to 0.7eV ∼< m{sub a} ∼< 300 keV, primarily by the cosmic deuterium abundance: axion decays would strongly modify the baryon-to-photon ratio at BBN relative to the one at CMB decoupling. Additional arguments include neutrino dilution relative to photons by axion decays and spectral CMB distortions. Our new cosmological constraints complement stellar-evolution and laboratory bounds.

  10. Couplings between QCD axion and photon from string compactification

    NASA Astrophysics Data System (ADS)

    Kim, Jihn E.; Nam, Soonkeon

    2016-08-01

    The QCD axion couplings of various invisible axion models are presented. In particular, the exact global symmetry U(1)PQ in the superpotential is possible for the anomalous U(1) from string compactification, broken only by the gauge anomalies at one loop level, and is shown to have the resultant invisible axion coupling to photon, caγγ ≥8/3 - caγγch br where caγγch br ≃ 2. However, this bound is not applicable in approximate U(1)PQ models with sufficiently suppressed U(1)PQ-breaking superpotential terms. We also present a simple method to obtain caγγ0 which is the value obtained above the electroweak scale.

  11. Leptogenesis from Left-Handed Neutrino Production during Axion Inflation

    NASA Astrophysics Data System (ADS)

    Adshead, Peter; Sfakianakis, Evangelos I.

    2016-03-01

    We propose that the observed matter-antimatter asymmetry can be naturally produced as a by-product of axion-driven slow-roll inflation by coupling the axion to standard model neutrinos. We assume that grand unified theory scale right-handed neutrinos are responsible for the masses of the standard model neutrinos and that the Higgs field is light during inflation and develops a Hubble-scale root-mean-square value. In this setup, the rolling axion generates a helicity asymmetry in standard model neutrinos. Following inflation, this helicity asymmetry becomes equal to a net lepton number as the Higgs condensate decays and is partially reprocessed by the S U (2 )L sphaleron into a net baryon number.

  12. Gravity waves and linear inflation from axion monodromy

    SciTech Connect

    McAllister, Liam; Silverstein, Eva; Westphal, Alexander

    2010-08-15

    Wrapped branes in string compactifications introduce a monodromy that extends the field range of individual closed-string axions to beyond the Planck scale. Furthermore, approximate shift symmetries of the system naturally control corrections to the axion potential. This suggests a general mechanism for chaotic inflation driven by monodromy-extended closed-string axions. We systematically analyze this possibility and show that the mechanism is compatible with moduli stabilization and can be realized in many types of compactifications, including warped Calabi-Yau manifolds and more general Ricci-curved spaces. In this broad class of models, the potential is linear in the canonical inflaton field, predicting a tensor to scalar ratio r{approx_equal}0.07 accessible to upcoming cosmic microwave background observations.

  13. Leptogenesis from Left-Handed Neutrino Production during Axion Inflation.

    PubMed

    Adshead, Peter; Sfakianakis, Evangelos I

    2016-03-01

    We propose that the observed matter-antimatter asymmetry can be naturally produced as a by-product of axion-driven slow-roll inflation by coupling the axion to standard model neutrinos. We assume that grand unified theory scale right-handed neutrinos are responsible for the masses of the standard model neutrinos and that the Higgs field is light during inflation and develops a Hubble-scale root-mean-square value. In this setup, the rolling axion generates a helicity asymmetry in standard model neutrinos. Following inflation, this helicity asymmetry becomes equal to a net lepton number as the Higgs condensate decays and is partially reprocessed by the SU(2)_{L} sphaleron into a net baryon number. PMID:26991168

  14. Pulsar timing signal from ultralight axion in f (R ) theory

    NASA Astrophysics Data System (ADS)

    Aoki, Arata; Soda, Jiro

    2016-04-01

    An ultralight axion around 1 0-23 eV is known as a viable dark matter candidate. A distinguished feature of such a dark matter is the oscillating pressure which produces the oscillation of the gravitational potential with frequency in the nano-Hz range. Recently, Khmelnitsky and Rubakov pointed out that this time dependent potential induces the pulse arrival residual and could be observed by the Square Kilometre Array (SKA) experiment. In this paper, we study the detectability of the oscillating pressure of the axion in the framework of f (R ) theory, and show that the amplitude of the gravitational potential can be enhanced or suppressed compared to that in Einstein's theory depending on the parameters of the f (R ) model and mass of the axion. In particular, we investigate the Hu-Sawicki model and find the condition that the Hu-Sawicki model is excluded.

  15. Level crossing between the QCD axion and an axionlike particle

    NASA Astrophysics Data System (ADS)

    Daido, Ryuji; Kitajima, Naoya; Takahashi, Fuminobu

    2016-04-01

    We study a level crossing between the QCD axion and an axionlike particle, focusing on the recently found phenomenon, the axion roulette, where the axionlike 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 charge parity problem.

  16. Gravity Waves and Linear Inflation From Axion Monodromy

    SciTech Connect

    McAllister, Liam; Silverstein, Eva; Westphal, Alexander; /SLAC /Stanford U., Phys. Dept.

    2010-08-26

    Wrapped branes in string compactifications introduce a monodromy that extends the field range of individual closed-string axions to beyond the Planck scale. Furthermore, approximate shift symmetries of the system naturally control corrections to the axion potential. This suggests a general mechanism for chaotic inflation driven by monodromy-extended closed-string axions. We systematically analyze this possibility and show that the mechanism is compatible with moduli stabilization and can be realized in many types of compactifications, including warped Calabi-Yau manifolds and more general Ricci-curved spaces. In this broad class of models, the potential is linear in the canonical inflaton field, predicting a tensor to scalar ratio r {approx} 0.07 accessible to upcoming cosmic microwave background (CMB) observations.

  17. Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

    NASA Astrophysics Data System (ADS)

    Higaki, Tetsutaro; Jeong, Kwang Sik; Kitajima, Naoya; Takahashi, Fuminobu

    2016-06-01

    We show that the required high quality of the Peccei-Quinn symmetry can be naturally explained in the aligned QCD axion models where the QCD axion arises from multiple axions with decay constants much smaller than the axion window, e.g., around the weak scale. Even in the presence of general Planck-suppressed Peccei-Quinn symmetry breaking operators, the effective strong CP phase remains sufficiently small in contrast to the standard axion models without the alignment. The QCD axion potential has small or large modulations due to the symmetry breaking operators, which can significantly affect the axion cosmology. When the axions are trapped in different minima, domain walls appear and their scaling behavior suppresses the axion isocurvature perturbations at super-horizon scales. Our scenario predicts many axions and saxions coupled to gluons, and they may be searched for at collider experiments. In particular, the recently found diphoton excess at 750 GeV could be due to one of such (s)axions.

  18. Constraining axion coupling constants from measuring the Casimir interaction between polarized test bodies

    NASA Astrophysics Data System (ADS)

    Bezerra, V. B.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Romero, C.

    2016-08-01

    We propose an experiment for measuring the effective Casimir pressure between two parallel silicon carbide (SiC) plates with aligned nuclear spins. The prospective constraints on an axion-neutron coupling constant for both hadronic and grand unified theory (GUT) axions are calculated using the process of one-axion exchange. For this purpose, a general expression for the additional pressure arising between two polarized plates due to the exchange of one axion between their constituent fermions is derived. We demonstrate that only the polarization component perpendicular to the plates contributes to the pressure. The obtained pressure can be both repulsive and attractive depending on whether the polarizations of both plates are unidirectional or directed in opposite directions. It is shown that although the constraints on an axion-electron coupling obtained in the case of magnetized plates are not competitive, the constraints on an axion-neutron coupling found for plates with polarized nuclear spins are of the same order of magnitude as those obtained previously for the GUT axions alone using the process of two-axion exchange. The proposed experiment allows us also to strengthen the presently known constraints on the axion-neutron coupling constants of GUT axions by using both processes of one- and two-axion exchange.

  19. Testing the ultra-light axion hypothesis using cosmic microwave background and galaxy clustering data

    NASA Astrophysics Data System (ADS)

    Grin, Daniel

    2015-08-01

    Ultra-light axions emerge from string theory and are attractive dark matter and dark energy candidates. After reviewing the motivation for ultra-light axions, I will discuss the cosmological observables in ultra-light axion cosmological scenarios, and then lay forth the methods and results of a recent search for such axions using CMB anisotropies and the clustering of galaxies, calling on Planck CMB data and the WiggleZ galaxy survey, respectively. I will then explain how isocurvature fluctuations in the CMB lead to an interesting tension between ultra-light axion dark matter and high-scale inflation, leading to interesting connections between the hunt for primordial CMB B-mode polarization and the ultra-light axion hypothesis. I will then survey the range of interesting future observational probes of the ultra-light axion dark matter hypothesis..

  20. Widening the Axion Window via Kinetic and Stückelberg Mixings

    NASA Astrophysics Data System (ADS)

    Shiu, Gary; Staessens, Wieland; Ye, Fang

    2015-10-01

    We point out that kinetic and Stückelberg mixings that are generically present in the low energy effective action of axions can significantly widen the window of axion decay constants. We show that an effective super-Planckian decay constant can be obtained even when the axion kinetic matrix has only sub-Planckian entries. Our minimal model involves only two axions, a Stückelberg U (1 ) and a modest rank instanton generating non-Abelian group. Below the mass of the Stückelberg U (1 ), there is only a single axion with a nonperturbatively generated potential. In contrast to previous approaches, the enhancement of the axion decay constant is not tied to the number of degrees of freedom introduced. We also discuss how kinetic mixings can lower the decay constant to the desired axion dark matter window. String theory embeddings of this scenario and their phenomenological features are briefly discussed.

  1. Widening the Axion Window via Kinetic and Stückelberg Mixings.

    PubMed

    Shiu, Gary; Staessens, Wieland; Ye, Fang

    2015-10-30

    We point out that kinetic and Stückelberg mixings that are generically present in the low energy effective action of axions can significantly widen the window of axion decay constants. We show that an effective super-Planckian decay constant can be obtained even when the axion kinetic matrix has only sub-Planckian entries. Our minimal model involves only two axions, a Stückelberg U(1) and a modest rank instanton generating non-Abelian group. Below the mass of the Stückelberg U(1), there is only a single axion with a nonperturbatively generated potential. In contrast to previous approaches, the enhancement of the axion decay constant is not tied to the number of degrees of freedom introduced. We also discuss how kinetic mixings can lower the decay constant to the desired axion dark matter window. String theory embeddings of this scenario and their phenomenological features are briefly discussed. PMID:26565455

  2. Constraints on neutrinos and axions from cosmology

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.

    1981-01-01

    A review is made of the astrophysical arguments with regard to neutrino properties. It is shown that the best fit to the present baryon density and He-4 abundance is obtained with three neutrino species. It is also shown that astrophysical constraints on neutrino and axion lifetime-mass combinations rule out weakly interacting particles with lifetimes between 1/1000 to 10 to the 23rd sec for M up to 10 MeV. There is an allowed astrophysical window for neutrinos with M up to 10 MeV and tau less than 1000 sec. The possible role of massive neutrinos in the dark mass of galaxies is discussed. It is shown that the baryon density in the universe is comparable to the density obtained from the dynamics of binary galaxies. Therefore, massive neutrinos are only required if the cosmological mass density is greater than that implied by binaries and small groups of galaxies. The only objects which might imply such high densities are large clusters. For neutrinos to cluster with these large clusters requires a neutrino mass of at least 3 eV.

  3. Solitons of axion-dilaton gravity

    SciTech Connect

    Bakas, I. |

    1996-11-01

    We use soliton techniques of the two-dimensional reduced {beta}-function equations to obtain nontrivial string backgrounds from flat space. These solutions are characterized by two integers ({ital n},{ital m}) referring to the soliton numbers of the metric and axion-dilaton sectors, respectively. We show that the Nappi-Witten universe associated with the SL(2){times}SU(2)/SO(1,1){times}U(1) CFT coset arises as a (1,1) soliton in this fashion for certain values of the moduli parameters, while for other values of the soliton moduli we arrive at the SL(2)/SO(1,1){times}SO(1,1){sup 2} background. Ordinary four-dimensional black holes arise as two-dimensional (2,0) solitons, while the Euclidean wormhole background is described as a (0,2) soliton on flat space. The soliton transformations correspond to specific elements of the string Geroch group. These could be used as a starting point for exploring the role of {ital U} dualities in string compactifications to two dimensions. {copyright} {ital 1996 The American Physical Society.}

  4. Axion-photon propagation in magnetized universe

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Lai, Dong

    2016-06-01

    Oscillations between photons and axion-like particles (ALP) travelling in intergalactic magnetic fields have been invoked to explain a number of astrophysical phenomena, or used to constrain ALP properties using observations. One example is the anomalous transparency of the universe to TeV gamma rays. The intergalactic magnetic field is usually modeled as patches of coherent domains, each with a uniform magnetic field, but the field orientation changes randomly from one domain to the next (``discrete-varphi model''). We show in this paper that in more realistic situations, when the magnetic field direction varies continuously along the propagation path, the photon-to-ALP conversion probability P can be significantly different from the discrete-varphi model. In particular, P has a distinct dependence on the photon energy and ALP mass, and can be as large as 100%. This result can affect previous constraints on ALP properties based on ALP-photon propagation in intergalactic magnetic fields, such as TeV photons from distant Active Galactic Nucleus.

  5. Mixed axion/neutralino cold dark matter in supersymmetric models

    SciTech Connect

    Baer, Howard; Lessa, Andre; Rajagopalan, Shibi; Sreethawong, Warintorn E-mail: lessa@nhn.ou.edu E-mail: wstan@nhn.ou.edu

    2011-06-01

    We consider supersymmetric (SUSY) models wherein the strong CP problem is solved by the Peccei-Quinn (PQ) mechanism with a concommitant axion/axino supermultiplet. We examine R-parity conserving models where the neutralino is the lightest SUSY particle, so that a mixture of neutralinos and axions serve as cold dark matter (a Z-tilde {sub 1} CDM). The mixed a Z-tilde {sub 1} CDM scenario can match the measured dark matter abundance for SUSY models which typically give too low a value of the usual thermal neutralino abundance, such as models with wino-like or higgsino-like dark matter. The usual thermal neutralino abundance can be greatly enhanced by the decay of thermally-produced axinos (ã) to neutralinos, followed by neutralino re-annihilation at temperatures much lower than freeze-out. In this case, the relic density is usually neutralino dominated, and goes as ∼ (f{sub a}/N)/m{sub ã}{sup 3/2}. If axino decay occurs before neutralino freeze-out, then instead the neutralino abundance can be augmented by relic axions to match the measured abundance. Entropy production from late-time axino decays can diminish the axion abundance, but ultimately not the neutralino abundance. In a Z-tilde {sub 1} CDM models, it may be possible to detect both a WIMP and an axion as dark matter relics. We also discuss possible modifications of our results due to production and decay of saxions. In the appendices, we present expressions for the Hubble expansion rate and the axion and neutralino relic densities in radiation, matter and decaying-particle dominated universes.

  6. Axion-like particle searches with sub-THz photons

    NASA Astrophysics Data System (ADS)

    Capparelli, L. M.; Cavoto, G.; Ferretti, J.; Giazotto, F.; Polosa, A. D.; Spagnolo, P.

    2016-06-01

    We propose a variation, based on very low energy and extremely intense photon sources, on the well established technique of Light-Shining-through-Wall (LSW) experiments for axion-like particle searches. With radiation sources at 30 GHz, we compute that present laboratory exclusion limits on axion-like particles might be improved by at least four orders of magnitude, for masses ma ≲ 0.01 meV. This could motivate research and development programs on dedicated single-photon sub-THz detectors.

  7. Finite axionic electrodynamics from a new non-commutative approach

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Spallucci, Euro

    2012-02-01

    Using the gauge-invariant but path-dependent variable formalism, we compute the static quantum potential for non-commutative axionic electrodynamics (or axionic electrodynamics in the presence of a minimal length). Accordingly, we obtain an ultraviolet finite static potential that is the sum of a Yukawa-type potential and a linear potential, leading to the confinement of static charges. Interestingly, it should be noted that this calculation involves no θ expansion at all. The present result manifests the key role played by the new quantum of length in our analysis.

  8. Quantized scalar field as DM: the axion's case

    SciTech Connect

    Barranco, J.; Bernal, A.

    2008-12-04

    We derive a rough estimation of the radius and the mass of a self-gravitating system made of axions. The system is a stationary solution of the Einstein-Klein-Gordon equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. We found that such system would have masses of the order of asteroids ({approx}10{sup -10} M{sub {center_dot}}) and radius of the order of few centimeters. Some implications of such type of objects are discussed.

  9. Axionic extension of the Einstein-aether theory

    NASA Astrophysics Data System (ADS)

    Balakin, Alexander B.

    2016-07-01

    We extend the Einstein-aether theory to take into account the interaction between a pseudoscalar field, which describes the axionic dark matter, and a timelike dynamic unit vector field, which characterizes the velocity of the aether motion. The Lagrangian of the Einstein-aether-axion theory includes cross terms based on the axion field and its gradient four-vector, on the covariant derivative of the aether velocity four-vector, and on the Riemann tensor and its convolutions. We follow the principles of the effective field theory, and include in the Lagrangian of interactions all possible terms up to the second order in the covariant derivative. The interpretation of new couplings is given in terms of irreducible parts of the covariant derivative of the aether velocity—namely, the acceleration four-vector, the shear and vorticity tensors, and the expansion scalar. A spatially isotropic and homogeneous cosmological model with a dynamic unit vector field and axionic dark matter is considered as an application of the established theory; new exact solutions are discussed, which describe models with big rip, pseudo-rip, and de Sitter-type asymptotic behavior.

  10. Axions, SN 1987A, and one pion exchange

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Kang, Ho-Shik; Steigman, Gary

    1988-01-01

    Nucleon-nucleon, axion bremsstrahlung is the primary mechanism for axion emission from the nascent neutron star associated with SN 1987A, and the rate for this process has been calculated in the one pion exchange approximation (OPE). The axion mass limit which follows from SN 1987A, m sub a less than or approx equal to 10 to the -3 eV, is the most stringent astrophysical bound, and has received much scrutiny. It has been suggested that by using OPE to calculate the cross section for the analog process, pp yields pp + pi sup o, and comparing the result of the experimental data one can test the validity of this approximation, and further, that such a comparison indicates that OPE leads to a value for this cross section which is a factor of 30 to 40 too large. If true, this would suggest that the axion mass limit should be revised upward by a factor of approximately 6. The cross section for pp yields pp + pi sup o using OPE is carefully evaluated, and excellent agreement found (to better than a factor of 2) with the experimental data.

  11. The Axion Dark Matter eXperiment Cryogenic System

    NASA Astrophysics Data System (ADS)

    Letourneau, Hannah; ADMX Collaboration

    2016-03-01

    The Axion Dark Matter eXperiment (ADMX) searches for dark matter axions by looking for their resonant conversion to photons in a microwave cavity in a high magnetic field. The mass of the axion (unknown) determines the frequency at which the axion couples to the magnetic field, so the cavity is tuned through a wide range of frequencies while measuring the power deposited in it with ultra-sensitive quantum electronics. The dominant systematic noise is from the noise temperature of the electronics; during the last data run they were cooled to 1.5K with a pumped He-4 refrigerator. Currently, we are installing a large dilution refrigerator, which will cool the cavity and first stage amplifiers to ~100 mK. I will discuss our progress, describe some of the challenges we have faced and how we have overcome them, and describe our plans for operation. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE- AC52-07NA27344, DE-AC03-76SF00098, and the Livermore LDRD program.

  12. Large-scale search for dark-matter axions

    SciTech Connect

    Kinion, D; van Bibber, K

    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.

  13. Axion Induced Oscillating Electric Dipole Moment of the Electron

    DOE PAGESBeta

    Hill, Christopher T.

    2016-01-12

    A cosmic axion, via the electromagnetic anomaly, induces an oscillating electric dipole for the electron of frequency ma and strength ~(few) x 10-32 e-cm, two orders of magnitude above the nucleon, and within a few orders of magnitude of the present standard model constant limit. We give a detailed study of this phenomenon via the interaction of the cosmic axion, through the electromagnetic anomaly, with particular emphasis on the decoupling limit of the axion, ∂ta(t) ∝ mα → 0. The analysis is subtle, and we find the general form of the action involves a local contact interaction and a nonlocalmore » contribution, analogous to the “transverse current” in QED, that enforces the decoupling limit. We carefully derive the effective action in the Pauli-Schroedinger non-relativistic formalism, and in Georgi’s heavy quark formalism adapted to the “heavy electron” (me >> ma). We compute the electric dipole radiation emitted by free electrons, magnets and currents, immersed in the cosmic axion field, and discuss experimental configurations that may yield a detectable signal.« less

  14. First axion results from the XENON100 experiment

    NASA Astrophysics Data System (ADS)

    Aprile, E.; Agostini, F.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Auger, M.; Balan, C.; Barrow, P.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Cardoso, J. M. R.; Colijn, A. P.; Contreras, H.; Cussonneau, J. P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; Itay, R.; Kaether, F.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Le Calloch, M.; Lellouch, D.; Levy, C.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Lyashenko, A.; Macmullin, S.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Mayani Paras, D.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Miguez, B.; Molinario, A.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Piastra, F.; Pienaar, J.; Plante, G.; Priel, N.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; Dos Santos, J. M. F.; Sartorelli, G.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.; Xenon100 Collaboration

    2014-09-01

    We present the first results of searches for axions and axionlike particles with the XENON100 experiment. The axion-electron coupling constant, gAe, has been probed by exploiting the axioelectric effect in liquid xenon. A profile likelihood analysis of 224.6 live days × 34-kg exposure has shown no evidence for a signal. By rejecting gAe larger than 7.7×10-12 (90% C.L.) in the solar axion search, we set the best limit to date on this coupling. In the frame of the DFSZ and KSVZ models, we exclude QCD axions heavier than 0.3 and 80 eV /c2, respectively. For axionlike particles, under the assumption that they constitute the whole abundance of dark matter in our galaxy, we constrain gAe to be lower than 1×10-12 (90% C.L.) for masses between 5 and 10 keV /c2.

  15. A visible QCD axion from an enlarged color group

    NASA Astrophysics Data System (ADS)

    Gherghetta, Tony; Nagata, Natsumi; Shifman, Mikhail

    2016-06-01

    We consider the possibility of an enlarged QCD color group, SU (3 +N') spontaneously broken to SU (3 )c×SU (N') with extra vectorlike quarks transforming in the fundamental representation. When the heavy quarks are integrated out below the PQ-breaking scale, they generate an axion coupling which simultaneously solves the strong C P problem for both gauge groups. However, the axion mass now receives a new nonperturbative contribution from the SU (N') confinement scale, which can be substantially larger than the QCD scale. This can increase the axion mass to be at or above the electroweak scale. This visible axion can then decay into gluons and photons giving rise to observable signals at run II of the LHC. In particular, if the mass is identified with the 750 GeV diphoton resonance, then the new confinement scale is ˜TeV and the PQ-breaking scale is ˜10 TeV . This predicts vectorlike quarks and a PQ scalar resonance in the multi-TeV range, with the possibility that dark matter is an SU (N') baryon.

  16. Limits on the abundance and coupling of cosmic axions

    SciTech Connect

    DePanfilis, S.; Melissinos, A.C.; Moskowitz, B.E.; Rogers, J.T.; Semertzidis, Y.K.; Wuensch, W.U.; Halama, H.J.; Prodell, A.G.; Fowler, W.B.; Kerns, Q.

    1987-03-01

    We report preliminary results from a search for galactic axions in the mass range 4.5 < m/sub a/ < 5.0 ..mu..eV. For an axion line width GAMMA/sub a/ less than or equal to 8 x 10/sup -13/ eV, we obtain the experimental limit (g/sub a..gamma gamma../m/sub a/)/sup 2/rho/sub a/ < 1.4 x 10/sup -41/. The theoretical prediction is (g/sub a..gamma gamma../m/sub a/)/sup 2/rho/sub a/ = 3.9 x 10/sup -44/ with the local galactic axion density rho/sub a/ = 300 MeV/cm/sup 3/. We have also searched for the presence of a continuous spectrum of light pseudoscalar particles; assuming that the local galactic axion density is composed of axions with masses uniformly distributed between 4.5 and 5.0 ..mu..eV, we find that g/sub a..gamma gamma../ < 2 x 10/sup -30/ MeV/sup 1/2/ cm/sup 3/2/ approx. = 10/sup 11/ GeV/sup -1/. Limits have also been set on the production of light pseudoscalar x particles; we find g/sub x..gamma gamma../ < 10/sup -24/ MeV/sup 1/2/ cm/sup 3/2/ approx. = 10/sup -5/ GeV/sup -1/ for 0< m/sub x/ less than or equal to 4..mu..eV. 20 refs., 7 figs., 1 tab.

  17. Hidden axion dark matter decaying through mixing with QCD axion and the 3.5 keV X-ray line

    SciTech Connect

    Higaki, Tetsutaro; Kitajima, Naoya; Takahashi, Fuminobu E-mail: kitajima@tuhep.phys.tohoku.ac.jp

    2014-12-01

    Hidden axions may be coupled to the standard model particles through a kinetic or mass mixing with QCD axion. We study a scenario in which a hidden axion constitutes a part of or the whole of dark matter and decays into photons through the mixing, explaining the 3.5 keV X-ray line signal. Interestingly, the required long lifetime of the hidden axion dark matter can be realized for the QCD axion decay constant at an intermediate scale, if the mixing is sufficiently small. In such a two component dark matter scenario, the primordial density perturbations of the hidden axion can be highly non-Gaussian, leading to a possible dispersion in the X-ray line strength from various galaxy clusters and near-by galaxies. We also discuss how the parallel and orthogonal alignment of two axions affects their couplings to gauge fields. In particular, the QCD axion decay constant can be much larger than the actual Peccei-Quinn symmetry breaking.

  18. Axion-induced oscillations of cooperative electric field in a cosmic magneto-active plasma

    NASA Astrophysics Data System (ADS)

    Balakin, Alexander B.; Muharlyamov, Ruslan K.; Zayats, Alexei E.

    2014-06-01

    We consider one cosmological application of an axionic extension of the Maxwell-Vlasov theory, which describes axionically induced oscillatory regime in the state of global magnetic field evolving in the anisotropic expanding (early) universe. We show that the cooperative electric field in the relativistic plasma, being coupled to the pseudoscalar (axion) and global magnetic fields, plays the role of a regulator in this three-level system; in particular, the cooperative (Vlasov) electric field converts the regime of anomalous growth of the pseudoscalar field, caused by the axion-photon coupling at the inflationary epoch of the universe expansion, into an oscillatory regime with finite density of relic axions. We analyze solutions to the dispersion equations for the axionically induced cooperative oscillations of the electric field in the relativistic plasma.

  19. QCD axion as a bridge between string theory and flavor physics

    NASA Astrophysics Data System (ADS)

    Ahn, Y. H.

    2016-04-01

    We construct a string-inspired model, motivated by the flavored Peccei-Quinn (PQ) axions, as a useful bridge between flavor physics and string theory. The key feature is two anomalous gauged U (1 ) symmetries, responsible for both the fermion mass hierarchy problem of the standard model and the strong C P problem, that combine string theory with flavor physics and severely constrain the form of the F- and D-term contributions to the potential. In the context of supersymmetric moduli stabilization we stabilize the size moduli with positive masses while leaving two axions massless and one axion massive. We demonstrate that, while the massive gauge bosons eat the two axionic degrees of freedom, two axionic directions survive to low energies as the flavored PQ axions.

  20. Early-universe thermal production of not-so-invisible axions

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1987-01-01

    It is found that, for Peccei-Quinn symmetry-breaking scales of less than about 4 x 10 to the 8th GeV (corresponding to axion masses of greater than about 0.03 eV) thermal production of axions in the early universe (via the Primakoff and photoproduction processes) dominates coherent production by a factor of about 1200/m sub a/(1 eV)/ exp 2.175. The photon luminosity from the decays of these relic axions leads to an upper limit to the axion mass of order 2-5 eV. If the axion mass saturates this bound, relic axion decays may well be detectable.

  1. Cosmological constraints on neutrino plus axion hot dark matter: update after WMAP-5

    SciTech Connect

    Hannestad, S; Mirizzi, A; Raffelt, G G; Wong, Y Y Y E-mail: amirizzi@mppmu.mpg.de E-mail: ywong@mppmu.mpg.de

    2008-04-15

    We update our previous constraints on two-component hot dark matter (axions and neutrinos), including the recent WMAP five-year data release. Marginalizing over {Sigma}m{sub {nu}} provides m{sub a}<1.02 eV (95% C.L.) for the axion mass. In the absence of axions we find {Sigma}m{sub {nu}}<0.63 eV (95% C.L.)

  2. The GammeV suite of experimental searches for axion-like particles

    SciTech Connect

    Steffen, Jason H.; Upadhye, Amol; /KICP, Chicago /Chicago U., EFI

    2009-08-01

    We report on the design and results of the GammeV search for axion-like particles and for chameleon particles. We also discuss plans for an improved experiment to search for chameleon particles, one which is sensitive to both cosmological and power-law chameleon models. Plans for an improved axion-like particle search using coupled resonant cavities are also presented. This experiment will be more sensitive to axion-like particles than stellar astrophysical models or current helioscope experiments.

  3. Axion-photon conversion in space and in low symmetrical dielectric crystals

    NASA Astrophysics Data System (ADS)

    Gorelik, V. S.

    2016-07-01

    The opportunities of axions detection as the result of axion-photon conversion processes in the space and in low symmetrical dielectric crystals are discussed. In accordance with the modern theory predictions, axions are pseudoscalar vacuum particles having very small (0.001-1.0 meV) rest energy. The possibility of axions conversion into photons and vice-versa processes in vacuum at the presence of outer magnetic field has been analyzed before. Pseudoscalar (axion type) modes are existing in some types of crystals. Polar pseudoscalar lattice and exciton modes in low symmetrical crystals are strongly interacted with axions. In this work, optical excitation of axion-type modes in low symmetrical crystals is proposed for observation of axion - photon conversion processes. Instead of outer magnetic field, the crystalline field of such crystals may be used. The experimental schemes for axion-photon conversion processes observation with recording the secondary emission of luminescence, infrared or Stimulated Raman Scattering in some dielectric crystals are discussed.

  4. SQUID-Based Microwave Cavity Search for Dark-Matter Axions

    SciTech Connect

    Asztalos, S. J.; Carosi, G.; Hagmann, C.; Kinion, D.; Bibber, K. van; Hotz, M.; Rosenberg, L. J; Rybka, G.; Hoskins, J.; Hwang, J.; Sikivie, P.; Tanner, D. B.; Bradley, R.; Clarke, J.

    2010-01-29

    Axions in the mueV 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 mueV and 3.53 mueV and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.

  5. Axion Bose-Einstein Condensation: a model beyond Cold Dark Matter

    SciTech Connect

    Yang, Q.

    2010-08-30

    Cold dark matter axions form a Bose-Einstein condensate if the axions thermalize. Recently, it was found [1] that they do thermalize when the photon temperature reaches T{approx}100 eV(f/10{sup 12} GeV){sup 1/2} and that they continue to do so thereafter. We discuss the differences between axion BEC and CDM in the linear regime and the non-linear regime of evolution of density perturbations. We find that axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multi-poles.

  6. A SQUID-Based RF Cavity Search for Dark Matter Axions

    NASA Astrophysics Data System (ADS)

    Hotz, Michael T.

    The axion is a hypothetical elementary particle resulting from a solution to the "Strong-CP" problem. This serious problem in the standard model of particle physics is manifested as a 1010 discrepancy between the measured upper limit and the calculated value of the neutron's electric dipole moment. Furthermore, a light (~mueV) axion is an ideal dark matter candidate: axions would have been copiously produced during the Big Bang and would be the primary component of the dark matter in the universe. The resolution of the Strong-CP problem and the discovery of the composition of dark matter are two of the most pressing problems in physics. The observation of a light, dark-matter axion would resolve both of these problems. The Axion Dark Matter eXperiment (ADMX) is the most sensitive search for dark-matter axions. Axions in our Milky Way Galaxy may scatter off a magnetic field and convert into microwave photons. ADMX consists of a tunable high-Q RF cavity within the bore of a large, 8.5 Tesla superconducting solenoidal magnet. When the cavity's resonant frequency matches the axion's total energy, the probability of axion-to-photon conversion is enhanced. The cavity's narrow bandwidth requires ADMX to slowly scan possible axion masses. A receiver amplifies, mixes, and digitizes the power developed in the cavity from possible axion-to-photon conversions. This is the most sensitive spectral receiver of microwave radiation in the world. The resulting data is scrutinized for an axion signal above the thermal background. ADMX first operated from 1995-2005 and produced exclusion limits on the energy of dark-matter axions from 1.9 mueV to 3.3 mueV. In order to improve on these limits and continue the search for plausible dark-matter axions, the system was considerably upgraded from 2005 until 2008. In the upgrade, the key technical advance was the use of a dc Superconducting QUantum Interference Device (SQUID) as a microwave amplifier. The SQUID amplifier's noise level is near

  7. Cosmologically Safe QCD Axion without Fine-Tuning

    NASA Astrophysics Data System (ADS)

    Yamada, Masaki; Yanagida, Tsutomu T.; Yonekura, Kazuya

    2016-02-01

    Although QCD axion models are widely studied as solutions to the strong C P problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory.

  8. Axion Dark Matter Coupling to Resonant Photons via Magnetic Field

    NASA Astrophysics Data System (ADS)

    McAllister, Ben T.; Parker, Stephen R.; Tobar, Michael E.

    2016-04-01

    We show that the magnetic component of the photon field produced by dark matter axions via the two-photon coupling mechanism in a Sikivie haloscope is an important parameter passed over in previous analysis and experiments. The interaction of the produced photons will be resonantly enhanced as long as they couple to the electric or magnetic mode structure of the haloscope cavity. For typical haloscope experiments the electric and magnetic couplings are equal, and this has implicitly been assumed in past sensitivity calculations. However, for future planned searches such as those at high frequency, which synchronize multiple cavities, the sensitivity will be altered due to different magnetic and electric couplings. We define the complete electromagnetic form factor and discuss its implications for current and future dark matter axion searches over a wide range of masses.

  9. Subleading effects and the field range in axion inflation

    NASA Astrophysics Data System (ADS)

    Parameswaran, Susha; Tasinato, Gianmassimo; Zavala, Ivonne

    2016-04-01

    An attractive candidate for the inflaton is an axion slowly rolling down a flat potential protected by a perturbative shift symmetry. Realisations of this idea within large field, natural and monomial inflation have been disfavoured by observations and are difficult to embed in string theory. We show that subleading, but significant non-perturbative corrections can superimpose sharp cliffs and gentle plateaus into the potential, whose overall effect is to enhance the number of e-folds of inflation. Sufficient e-folds are therefore achieved for smaller field ranges compared to the potential without such corrections. Thus, both single-field natural and monomial inflation in UV complete theories like string theory, can be restored into the favour of current observations, with distinctive signatures. Tensor modes result un-observably small, but there is a large negative running of the spectral index. Remarkably, natural inflation can be achieved with a single field whose axion decay constant is sub-Planckian.

  10. Axion monodromy inflation with multi-natural modulations

    SciTech Connect

    Higaki, Tetsutaro; Kobayashi, Tatsuo; Yamaguchi, Yuya; Seto, Osamu E-mail: kobayashi@particle.sci.hokudai.ac.jp E-mail: yy@particle.sci.hokudai.ac.jp

    2014-10-01

    We study parameter space in the axion monodromy inflation corrected by dynamically generated terms involving with the axion. The potential has the linear term with multiple sinusoidal functions, which play a role in generating modulations. We show that this potential leads both to a large tensor-to-scalar ratio r{sub T} ∼ 0.16 and to a large negative running of spectral index α{sub s} ∼ - (0.02 -0.03), ameliorating the tension between the result of the PLANCK and that of the BICEP2. To realize these results, a small hierarchy among dynamical scales is required whereas the decay constants in sinusoidal functions remain sub-Planckian in this model. We discuss also reheating process after the inflation in a bottom-up approach.

  11. Axion Dark Matter Coupling to Resonant Photons via Magnetic Field.

    PubMed

    McAllister, Ben T; Parker, Stephen R; Tobar, Michael E

    2016-04-22

    We show that the magnetic component of the photon field produced by dark matter axions via the two-photon coupling mechanism in a Sikivie haloscope is an important parameter passed over in previous analysis and experiments. The interaction of the produced photons will be resonantly enhanced as long as they couple to the electric or magnetic mode structure of the haloscope cavity. For typical haloscope experiments the electric and magnetic couplings are equal, and this has implicitly been assumed in past sensitivity calculations. However, for future planned searches such as those at high frequency, which synchronize multiple cavities, the sensitivity will be altered due to different magnetic and electric couplings. We define the complete electromagnetic form factor and discuss its implications for current and future dark matter axion searches over a wide range of masses. PMID:27152793

  12. Axion cosmology, lattice QCD and the dilute instanton gas

    NASA Astrophysics Data System (ADS)

    Borsanyi, Sz.; Dierigl, M.; Fodor, Z.; Katz, S. D.; Mages, S. W.; Nogradi, D.; Redondo, J.; Ringwald, A.; Szabo, K. K.

    2016-01-01

    Axions are one of the most attractive dark matter candidates. The evolution of their number density in the early universe can be determined by calculating the topological susceptibility χ (T) of QCD as a function of the temperature. Lattice QCD provides an ab initio technique to carry out such a calculation. A full result needs two ingredients: physical quark masses and a controlled continuum extrapolation from non-vanishing to zero lattice spacings. We determine χ (T) in the quenched framework (infinitely large quark masses) and extrapolate its values to the continuum limit. The results are compared with the prediction of the dilute instanton gas approximation (DIGA). A nice agreement is found for the temperature dependence, whereas the overall normalization of the DIGA result still differs from the non-perturbative continuum extrapolated lattice results by a factor of order ten. We discuss the consequences of our findings for the prediction of the amount of axion dark matter.

  13. Cosmologically Safe QCD Axion without Fine-Tuning.

    PubMed

    Yamada, Masaki; Yanagida, Tsutomu T; Yonekura, Kazuya

    2016-02-01

    Although QCD axion models are widely studied as solutions to the strong CP problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory. PMID:26894701

  14. Constraining the axion-photon coupling with massive stars.

    PubMed

    Friedland, Alexander; Giannotti, Maurizio; Wise, Michael

    2013-02-01

    We point out that stars in the mass window ~8-12M([circumpunct]) can serve as sensitive probes of the axion-photon interaction, g(Aγγ). Specifically, for these stars axion energy losses from the helium-burning core would shorten and eventually eliminate the blue loop phase of the evolution. This would contradict observational data, since the blue loops are required, e.g., to account for the existence of Cepheid stars. Using the MESA stellar evolution code, modified to include the extra cooling, we conservatively find g(Aγγ)

  15. Reply to "Comment on `Axion Induced Oscillating Electric Dipole Moments' "

    SciTech Connect

    Hill, Christopher T.

    2015-10-19

    A recent paper of Flambaum, Roberts and Stadnik, [1], claims there is no induced oscillating electric dipole moment (OEDM), eg, for the electron, arising from the oscillating cosmic axion background via the anomaly. This claim is based upon the assumption that electric dipoles always be defined by their coupling to static (constant in time) electric fields. The relevant Feynman diagram, as computed by [1], then becomes a total divergence, and vanishes in momentum space. However, an OEDM does arise from the anomaly, coupled to time dependent electric fields. It shares the decoupling properties with the anomaly. The full action, in an arbitrary gauge, was computed in [2], [3]. It is nonvanishing with a time dependent outgoing photon, and yields physics, eg, electric dipole radiation of an electron immersed in a cosmic axion field.

  16. Axion inflation with gauge field production and primordial black holes

    NASA Astrophysics Data System (ADS)

    Bugaev, Edgar; Klimai, Peter

    2014-11-01

    We study the process of primordial black hole (PBH) formation at the beginning of the radiation era for the cosmological scenario in which the inflaton is a pseudo-Nambu-Goldstone boson (axion) and there is a coupling of the inflaton with some gauge field. In this model inflation is accompanied by the gauge quanta production, and a strong rise of the curvature power spectrum amplitude at small scales (along with non-Gaussianity) is predicted. We show that data on PBH searches can be used for a derivation of essential constraints on the model parameters in such an axion inflation scenario. We compare our numerical results with the similar results published earlier, in the work [A. Linde, S. Mooij, and E. Pajer, Phys. Rev. D 87, 103506 (2013)].

  17. Relativistic soliton collisions of axion type dark matter

    NASA Astrophysics Data System (ADS)

    Castañeda Valle, David; Mielke, Eckehard W.

    2016-07-01

    Axion-like scalar fields and the Lane-Emden (LE) truncation of their periodic potential are analyzed as a toy model of dark matter halos. Then, collisions of the well-known kinks in (1 + 1) spacetime dimensions can be mapped to those of localized lumps of the LE equation. Here, we generalize this mapping to (2 + 1)D or even (3 + 1)D and discuss a challenging intrinsic inelastic effect during relativistic soliton collisions.

  18. Axion electrodynamics and nonrelativistic photons in nuclear and quark matter

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naoki

    2016-04-01

    We argue that the effective theory for electromagnetic fields in spatially varying meson condensations in dense nuclear and quark matter is given by the axion electrodynamics. We show that one of the helicity states of photons there has the nonrelativistic gapless dispersion relation ω ˜k2 at small momentum, while the other is gapped. This "nonrelativistic photon" may also be realized at the interface between topological and trivial insulators in condensed matter systems.

  19. Oscillations in the CMB from axion monodromy inflation

    SciTech Connect

    Flauger, Raphael; McAllister, Liam; Pajer, Enrico; Xu, Gang; Westphal, Alexander E-mail: mcallister@cornell.edu E-mail: awestpha@stanford.edu

    2010-06-01

    We study the CMB observables in axion monodromy inflation. These well-motivated scenarios for inflation in string theory have monomial potentials over super-Planckian field ranges, with superimposed sinusoidal modulations from instanton effects. Such periodic modulations of the potential can drive resonant enhancements of the correlation functions of cosmological perturbations, with characteristic modulations of the amplitude as a function of wavenumber. We give an analytical result for the scalar power spectrum in this class of models, and we determine the limits that present data places on the amplitude and frequency of modulations. Then, incorporating an improved understanding of the realization of axion monodromy inflation in string theory, we perform a careful study of microphysical constraints in this scenario. We find that detectable modulations of the scalar power spectrum are commonplace in well-controlled examples, while resonant contributions to the bispectrum are undetectable in some classes of examples and detectable in others. We conclude that resonant contributions to the spectrum and bispectrum are a characteristic signature of axion monodromy inflation that, in favorable cases, could be detected in near-future experiments.

  20. Oscillations in the CMB from Axion Monodromy Inflation

    SciTech Connect

    Flauger, Raphael; McAllister, Liam; Pajer, Enrico; Westphal, Alexander; Xu, Gang; /Cornell U., Phys. Dept.

    2011-12-01

    We study the CMB observables in axion monodromy inflation. These well-motivated scenarios for inflation in string theory have monomial potentials over super-Planckian field ranges, with superimposed sinusoidal modulations from instanton effects. Such periodic modulations of the potential can drive resonant enhancements of the correlation functions of cosmological perturbations, with characteristic modulations of the amplitude as a function of wavenumber. We give an analytical result for the scalar power spectrum in this class of models, and we determine the limits that present data places on the amplitude and frequency of modulations. Then, incorporating an improved understanding of the realization of axion monodromy inflation in string theory, we perform a careful study of microphysical constraints in this scenario. We find that detectable modulations of the scalar power spectrum are commonplace in well-controlled examples, while resonant contributions to the bispectrum are undetectable in some classes of examples and detectable in others. We conclude that resonant contributions to the spectrum and bispectrum are a characteristic signature of axion monodromy inflation that, in favorable cases, could be detected in near-future experiments.

  1. The curvature perturbation in the axion-type curvaton model

    SciTech Connect

    Chingangbam, Pravabati; Huang, Qing-Guo E-mail: huangqg@kias.re.kr

    2009-04-15

    We study the axion-type curvaton model, with emphasis on the large field regime where analytic results are very difficult to obtain. We evaluate the tensor-scalar ratio r using WMAP normalization and the non-linearity parameters f{sub NL} and g{sub NL} by solving the equations numerically using the {delta}N formalism. We compare them with results for the curvaton with quadratic potential. We find that r is much smaller for the axion-type case compared to the result from the quadratic potential, with the difference increasingly more pronounced at larger field values. g{sub NL} is found to be positive, unlike the quadratic case where it is negative, and the amplitude of g{sub NL} is much larger. Moreover, there is a nearly linear scaling between g{sub NL} and f{sub NL}, with small deviation from linearity at large field values. The slope between g{sub NL} and f{sub NL} depends on the parameters characterizing the axion-type curvaton model. We further consider a mixed scenario where both the inflaton and the curvaton contribute to the primordial power spectrum and the non-Gaussianity parameters are found to be much larger than those in the case with quadratic potential.

  2. Observational evidence for gravitationally trapped massive axion(-like) particles

    NASA Astrophysics Data System (ADS)

    Dilella, L.; Zioutas, K.

    2003-04-01

    Several unexpected astrophysical observations can be explained by gravitationally captured massive axions or axion-like particles, which are produced inside the Sun or other stars and are accumulated over cosmic times. Their radiative decay in solar outer space would give rise to a `self-irradiation' of the whole star, providing the time-independent component of the corona heating source (we do not address here the flaring Sun). In analogy with the Sun-irradiated Earth atmosphere, the temperature and density gradient in the corona-chromosphere transition region is suggestive for an omnipresent irradiation of the Sun, which is the strongest evidence for the generic axion-like scenario. The same mechanism is compatible with phenomena like the solar wind, the X-rays from the dark-side of the Moon, the X-ray background radiation, the diffuse X-ray excesses (below ~1 keV), the non-cooling of oldest stars, etc. A temperature of ~106 K is observed in various places, while the radiative decay of a population of such elusive particles mimics a hot gas, which fits unexpected astrophysical X-ray observations. Furthermore, the recently reconstructed quiet solar X-ray spectrum during solar minimum supports this work, since it covers the expected energy range, and it is consistent with the result of a simulation based on Kaluza-Klein axions above ~1 keV. The derived axion luminosity (La~0.16Lsolar) fits the cosmic energy density spectrum and is compatible within 2/σ with the recent SNO result, showing the important interplay between any exotic energy loss mechanism and neutrino production. At lower energies, using also a ROSAT observation, only ~3% of the X-ray intensity is explained. Data from orbiting X-ray telescopes provide upper limits for particle decay rates 1 a.u. from the Sun, and suggest new types of searches on Earth or in space. In particular, X-ray observatories, with an unrivalled equivalent fiducial volume of ~103 m3 for the 0.1-10 keV range, can search for the

  3. Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

    NASA Astrophysics Data System (ADS)

    Berenji, B.; Gaskins, J.; Meyer, M.

    2016-02-01

    We present constraints on the nature of axions and axionlike particles (ALPs) by analyzing gamma-ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong C P problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon-nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma-ray spectrum arising from subsequent axion decays. By analyzing five years of gamma-ray data (between 60 and 200 MeV) for a sample of four nearby neutron stars, we do not find evidence for an axion or ALP signal; thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9 ×10-2 eV , which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6 ×107 GeV . Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.

  4. Axionic domain wall number related to U(1)anom global symmetry

    NASA Astrophysics Data System (ADS)

    Kim, Jihn E.

    2016-08-01

    The QCD axion with fa at an intermediate scale, 109 GeV ∼1012 GeV, seems in conflict with the gravity spoil of global symmetries and may face the axionic domain wall problem. We point out that the string compactifications with an anomalous U(1) gauge symmetry, allowing desirable chiral matter spectra, circumvent these two problems simultaneously.

  5. The search for axion-like dark matter using magnetic resonance

    NASA Astrophysics Data System (ADS)

    Sushkov, Alexander; Casper Collaboration

    2016-05-01

    The nature of dark matter is one of the most important open problems in modern physics, and it is necessary to develop techniques to search for a wide class of dark-matter candidates. Axions, originally introduced to resolve the strong CP problem in quantum chromodynamics (QCD), and axion-like particles (ALPs) are strongly motivated dark matter candidates. Nuclear spins interacting with axion-like background dark matter experience an energy shift, oscillating at the frequency equal to the axion Compton frequency. The Cosmic Axion Spin Precession Experiments (CASPEr) use precision magnetometry and nuclear magnetic resonance techniques to search for the effects of this interaction. The experimental signature is precession of the nuclear spins under the condition of magnetic resonance: when the bias magnetic field is tuned such that the nuclear spin sublevel splitting is equal to the axion Compton frequency. These experiments have the potential to detect axion-like dark matter in a wide mass range (10-12 eV to 10-6 eV, scanned by changing the bias magnetic field from approximately 1 gauss to 20 tesla) and with coupling strengths many orders of magnitude beyond the current astrophysical and laboratory limits, and all the way down to those corresponding to the QCD axion. Supported by the Heising-Simons Foundation.

  6. Determination of effective axion masses in the helium-3 buffer of CAST

    SciTech Connect

    Ruz, J

    2011-11-18

    The CERN Axion Solar Telescope (CAST) is a ground based experiment located in Geneva (Switzerland) searching for axions coming from the Sun. Axions, hypothetical particles that not only could solve the strong CP problem but also be one of the favored candidates for dark matter, can be produced in the core of the Sun via the Primakoff effect. They can be reconverted into X-ray photons on Earth in the presence of strong electromagnetic fields. In order to look for axions, CAST points a decommissioned LHC prototype dipole magnet with different X-ray detectors installed in both ends of the magnet towards the Sun. The analysis of the data acquired during the first phase of the experiment yielded the most restrictive experimental upper limit on the axion-to-photon coupling constant for axion masses up to about 0.02 eV/c{sup 2}. During the second phase, CAST extends its mass sensitivity by tuning the electron density present in the magnetic field region. Injecting precise amounts of helium gas has enabled CAST to look for axion masses up to 1.2 eV/c{sup 2}. This paper studies the determination of the effective axion masses scanned at CAST during its second phase. The use of a helium gas buffer at temperatures of 1.8 K has required a detailed knowledge of the gas density distribution. Complete sets of computational fluid dynamic simulations validated with experimental data have been crucial to obtain accurate results.

  7. Excess astrophysical photons from a 0.1-1 keV cosmic axion background.

    PubMed

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

    Primordial decays of string theory moduli at z~10(12) naturally generate a dark radiation cosmic axion background with 0.1-1 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings <10(-11) GeV(-1). We propose that axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario. PMID:24160588

  8. Search for solar axions produced by Primakoff conversion using resonant absorption by 169Tm nuclei

    NASA Astrophysics Data System (ADS)

    Derbin, A. V.; Bakhlanov, S. V.; Egorov, A. I.; Mitropol'Sky, I. A.; Muratova, V. N.; Semenov, D. A.; Unzhakov, E. V.

    2009-07-01

    The search for resonant absorption of the Primakoff solar axions by 169Tm nuclei have been performed. Such an absorption should lead to the excitation of low-lying nuclear energy level: A+Tm169→Tm∗169→Tm169+γ (8.41 keV). The Si(Li) detector and 169Tm target placed inside the low-background setup were used for that purpose. As a result, a new restriction on the axion-photon coupling and axion mass was obtained: g(GeV)ṡm(eV)⩽1.36×10 (90% c.l.). In model of hadronic axion this restriction corresponds to the upper limit on axion mass —m⩽191 eV for 90% c.l.

  9. Constraints on axion-nucleon coupling constants from measuring the Casimir force between corrugated surfaces

    NASA Astrophysics Data System (ADS)

    Bezerra, V. B.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Romero, C.

    2014-09-01

    We obtain stronger laboratory constraints on the coupling constants of axion-like particles to nucleons from measurements of the normal and lateral Casimir forces between sinusoidally corrugated surfaces of a sphere and a plate. For this purpose, the normal and lateral additional forces arising in the experimental configurations due to the two-axion exchange between protons and neutrons are calculated. Our constraints following from measurements of the normal and lateral Casimir forces are stronger than the laboratory constraints reported so far for masses of axion-like particles larger than 11 and 8 eV, respectively. A comparison between various laboratory constraints on the coupling constants of axion-like particles to nucleons obtained from the magnetometer measurements, Eötvos- and Cavendish-type experiments, and from the Casimir effect is performed over the wide range of masses of axion-like particles from 10-10 to 20 eV.

  10. The QUAX proposal: a search of galactic axion with magnetic materials

    NASA Astrophysics Data System (ADS)

    Ruoso, G.; Lombardi, A.; Ortolan, A.; Pengo, R.; Braggio, C.; Carugno, G.; Gallo, C. S.; Speake, C. C.

    2016-05-01

    Aim of the QUAX (QUaerere AXion) proposal is to exploit the interaction of cosmological axions with the spin of electrons in a magnetized sample. Their effect is equivalent to the application of an oscillating rf field with frequency and amplitude which are fixed by axion mass and coupling constant, respectively. The rf receiver module of the QUAX detector consists of magnetized samples with the Larmor resonance frequency tuned to the axion mass by a polarizing static magnetic field. The interaction of electrons with the axion-equivalent rf field produces oscillations in the total magnetization of the samples. To amplify such a tiny field, a pump field at the same frequency is applied in a direction orthogonal to the polarizing field. The induced oscillatory magnetization along the polarizing field is measured by a SQUID amplifier operated at its quantum noise level.