Articles de revues : « Axion cosmology »

1

Marsh, David J. E. « Axion cosmology ». Physics Reports 643 (juillet 2016) : 1–79. http://dx.doi.org/10.1016/j.physrep.2016.06.005.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

2

Turner, Michael S., et Frank Wilczek. « Inflationary axion cosmology ». Physical Review Letters 66, n^o 1 (7 janvier 1991) : 5–8. http://dx.doi.org/10.1103/physrevlett.66.5.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

3

Bachlechner, Thomas C., Kate Eckerle, Oliver Janssen et Matthew Kleban. « Axion landscape cosmology ». Journal of Cosmology and Astroparticle Physics 2019, n^o 09 (27 septembre 2019) : 062. http://dx.doi.org/10.1088/1475-7516/2019/09/062.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

4

LYTH, D. H. « Inflationary Axion Cosmology ». Annals of the New York Academy of Sciences 647, n^o 1 Texas/ESO-Cer (décembre 1991) : 736–42. http://dx.doi.org/10.1111/j.1749-6632.1991.tb32226.x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

5

CHOI, KIWOON. « THERMAL PRODUCTION OF AXINO DARK MATTER ». International Journal of Modern Physics : Conference Series 10 (janvier 2012) : 107–14. http://dx.doi.org/10.1142/s2010194512005818.

Texte intégral

Résumé :

We discuss certain features of the low energy effective interactions of axion supermultiplet, which are relevant for axino cosmology, and examine the implication to thermal production of axino in the early Universe.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Linde, A. D. « Inflation and axion cosmology ». Physics Letters B 201, n^o 4 (février 1988) : 437–39. http://dx.doi.org/10.1016/0370-2693(88)90597-7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

7

Patrascu, Andrei T. « H0 Tensions in Cosmology and Axion Pseudocycles in the Stringy Universe ». Universe 8, n^o 10 (22 septembre 2022) : 500. http://dx.doi.org/10.3390/universe8100500.

Texte intégral

Résumé :

The tension between early and late H0 is revised in the context of axion dark matter arising naturally from string theoretical integrations of antisymmetric tensor fields over non-trivial cycles. Certain early universe cycles may appear non-trivial from the perspective of a homology analysis focused on the early universe, while they may become trivial when analysed from the perspective of a homology theory reaching out to lower energies and later times. Such phenomena can introduce variations in the axion potential that would explain the observed H0 tension. The decay of such pseudo-axions when the pseudo-cycles dissipate trigger axion-two-photon (otherwise having an extremely long lifetime) and axion-gravitational processes mediated by Chern–Simons couplings with observable electromagnetic or gravitational wave signals originating in the early universe.

Styles APA, Harvard, Vancouver, ISO, etc.

8

MAHARANA, JNANADEVA. « SYMMETRIES OF AXION–DILATON STRING COSMOLOGY ». International Journal of Modern Physics A 20, n^o 07 (20 mars 2005) : 1441–69. http://dx.doi.org/10.1142/s0217751x05021105.

Texte intégral

Résumé :

The axion–dilaton string effective action is expressed in Einstein frame metric in a manifestly S-duality invariant form. It is shown that the moduli can be redefined to describe surface of a (2+1)-dimensional pseudosphere. The classical cosmological solutions of axion–dilaton are revisited. The Wheeler–DeWitt equation for the system is exactly solved and complete set of eigenfunctions are presented. The wave function factorizes and the one depending on the moduli is obtained by appealing to the underlying S-duality symmetry. Axion and dilaton parametrize [Formula: see text], the S-duality group, and the Hamiltonian is expressed as a sum of the Ricci scalar and the Casimir of SU (1, 1). Therefore, the complete set of wave functions, depending on the moduli, is obtained from group theory technique. The evidence for the existence of a W-infinity algebra in axion–dilaton cosmology is presented and the origin of the algebra is primarily due to high degree of degeneracies in the wave functions. It is qualitatively argued that axion–dilaton quantum cosmology exhibits chaotic behavior in the semiclassical limit.

Styles APA, Harvard, Vancouver, ISO, etc.

9

SIKIVIE, P. « DARK MATTER AXIONS ». International Journal of Modern Physics A 25, n^o 02n03 (30 janvier 2010) : 554–63. http://dx.doi.org/10.1142/s0217751x10048846.

Texte intégral

Résumé :

The hypothesis of an 'invisible' axion was made by Misha Shifman and others, approximately thirty years ago. It has turned out to be an unusually fruitful idea, crossing boundaries between particle physics, astrophysics and cosmology. An axion with mass of order 10-5 eV (with large uncertainties) is one of the leading candidates for the dark matter of the universe. It was found recently that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). Because they form a BEC, axions differ from ordinary cold dark matter (CDM) in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles. Because there is evidence for these phenomena, unexplained with ordinary CDM, an argument can be made that the dark matter is axions.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Saharian, A. A., et A. V. Timoshkin. « The Holographic cosmology with axion field ». International Journal of Geometric Methods in Modern Physics 18, n^o 11 (2 juillet 2021) : 2150174. http://dx.doi.org/10.1142/s0219887821501747.

Texte intégral

Résumé :

In this paper, we considered an axion F(R) gravity model and described, with the help of holographic principle, the cosmological models of viscous dark fluid coupled with axion matter in a spatially flat Friedmann–Robertson–Walker (FRW) universe. This description based on generalized infrared-cutoff holographic dark energy was proposed by Nojiri and Odintsov. We explored the Little Rip, the Pseudo Rip, and the power-law bounce cosmological models in terms of the parameters of the inhomogeneous equation of the state of viscous dark fluid and calculated the infrared cutoffs analytically. We represented the energy conservation equation for the dark fluid from a holographic point of view and showed a correspondence between the cosmology of a viscous fluid and holographic cosmology. We analyzed the autonomous dynamic system. In the absence of interaction between fluids, solutions are obtained corresponding to two cases. In the first case, dark energy is missing and the extension describes the component of dark matter. The second case corresponds to cosmological models with an extension due to dark energy. The solutions obtained are investigated for stability. For a cosmological model with the interaction of a special type, the stability of solutions of the dynamic system is also investigated.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Cuesta, A. J., M. E. Gómez, J. I. Illana et M. Masip. « Cosmology of an axion-like majoron ». Journal of Cosmology and Astroparticle Physics 2022, n^o 04 (1 avril 2022) : 009. http://dx.doi.org/10.1088/1475-7516/2022/04/009.

Texte intégral

Résumé :

Abstract We propose a singlet majoron model that defines an inverse seesaw mechanism in the ν sector. The majoron ϕ has a mass mϕ ≈ 0.5 eV and a coupling to the τ lepton similar to the one to neutrinos. In the early universe it is initially in thermal equilibrium, then it decouples at T ≈ 500 GeV and contributes with just ΔN eff = 0.026 during BBN. At T = 26 keV (final stages of BBN) a primordial magnetic field induces resonant γ ⟷ ϕ oscillations that transfer 6% of the photon energy into majorons, implying ΔN eff = 0.55 and a 4.7% increase in the baryon to photon ratio. At T ≈ mϕ the majoron enters in thermal contact with the heaviest neutrino and it finally decays into νν̅ pairs near recombination, setting ΔN eff = 0.85. The boost in the expansion rate at later times may relax the Hubble tension (we obtain H 0 = (71.4 ± 0.5) km/s/Mpc), while the processes νν̅ ⟷ ϕ suppress the free streaming of these particles and make the model consistent with large scale structure observations. Its lifetime and the fact that it decays into neutrinos instead of photons lets this axion-like majoron avoid the strong bounds that affect other axion-like particles of similar mass and coupling to photons.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Catena, Riccardo, et Jan Möller. « Axion–dilaton cosmology and dark energy ». Journal of Cosmology and Astroparticle Physics 2008, n^o 03 (17 mars 2008) : 012. http://dx.doi.org/10.1088/1475-7516/2008/03/012.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

13

Hashimoto, M., K. I. Izawa, M. Yamaguchi et T. Yanagida. « Axion cosmology with its scalar superpartner ». Physics Letters B 437, n^o 1-2 (octobre 1998) : 44–50. http://dx.doi.org/10.1016/s0370-2693(98)00887-9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

14

Arias, Paola, Nicolás Bernal, Dimitrios Karamitros, Carlos Maldonado, Leszek Roszkowski et Moira Venegas. « New opportunities for axion dark matter searches in nonstandard cosmological models ». Journal of Cosmology and Astroparticle Physics 2021, n^o 11 (1 novembre 2021) : 003. http://dx.doi.org/10.1088/1475-7516/2021/11/003.

Texte intégral

Résumé :

Abstract We study axion dark matter production from a misalignment mechanism in scenarios featuring a general nonstandard cosmology. Before the onset of Big Bang nucleosynthesis, the energy density of the universe is dominated by a particle field ϕ described by a general equation of state ω. The ensuing enhancement of the Hubble expansion rate decreases the temperature at which axions start to oscillate, opening this way the possibility for axions heavier than in the standard window. This is the case for kination, or in general for scenarios with ω > 1/3. However, if ω < 1/3, as in the case of an early matter domination, the decay of ϕ injects additional entropy relative to the case of the standard model, diluting this way the preexisting axion abundance, and rendering lighter axions viable. For a misalignment angle 0.5 < θ_i < π/√(3), the usual axion window becomes expanded to 4 × 10-9 eV ≲ ma ≲ 2 × 10-5 eV for the case of an early matter domination, or to 2 × 10-6 eV ≲ ma ≲ 10-2 eV for the case of kination. Interestingly, the coupling axion-photon in such a wider range can be probed with next generation experiments such as ABRACADABRA, KLASH, ADMX, MADMAX, and ORGAN. Axion dark matter searches may therefore provide a unique tool to probe the history of the universe before Big Bang nucleosynthesis.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Mazde, Kratika, et Luca Visinelli. « The interplay between the dark matter axion and primordial black holes ». Journal of Cosmology and Astroparticle Physics 2023, n^o 01 (1 janvier 2023) : 021. http://dx.doi.org/10.1088/1475-7516/2023/01/021.

Texte intégral

Résumé :

Abstract If primordial black holes (PBHs) had come to dominate the energy density of the early Universe when oscillations in the axion field began, we show that the relic abundance and expected mass range of the QCD axion would be greatly modified. Since the QCD axion is a potential candidate for dark matter (DM), we refer to it as the DM axion. We predominantly explore PBHs in the mass range (106 - 5× 108)g. We investigate the relation between the relic abundance of DM axions and the parameter space of PBHs. We numerically solve the set of Boltzmann equations, that governs the cosmological evolution during both radiation and PBH-dominated epochs, providing the bulk energy content of the early Universe. We further solve the equation of motion of the DM axion field to obtain its present abundance. Alongside non-relativistic production mechanisms, light QCD axions are generated from evaporating PBHs through the Hawking mechanism and could make up a fraction of the dark radiation (DR). If the QCD axion is ever discovered, it will give us insight into the early Universe and probe into the physics of the PBH-dominated era. We estimate the bounds on the model from DR axions produced via PBH evaporation and thermal decoupling, and we account for isocurvature bounds for the period of inflation where the Peccei-Quinn symmetry is broken. We assess the results obtained against the available CMB data and we comment on the forecasts from gravitational wave searches. We briefly state the consequences of PBH accretion and the uncertainties this may further add to cosmology and astroparticle physics modeling.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Evans, Nick, Stephen D. H. Hsu, Andreas Nyffeler et Myckola Schwetz. « QCD at large θ-angle axion cosmology ». Nuclear Physics B 494, n^o 1-2 (juin 1997) : 200–210. http://dx.doi.org/10.1016/s0550-3213(97)00174-0.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

17

Maharana, Jnanadeva. « Novel symmetries in axion-dilaton string cosmology ». Physics Letters B 549, n^o 1-2 (novembre 2002) : 7–12. http://dx.doi.org/10.1016/s0370-2693(02)02867-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

18

Hiramatsu, Takashi, Masahiro Kawasaki, Ken'ichi Saikawa et Toyokazu Sekiguchi. « Axion cosmology with long-lived domain walls ». Journal of Cosmology and Astroparticle Physics 2013, n^o 01 (2 janvier 2013) : 001. http://dx.doi.org/10.1088/1475-7516/2013/01/001.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

Kim, Jihn E. « The invisible axion, the gravitino and cosmology ». Nuclear Physics B 252 (janvier 1985) : 245–60. http://dx.doi.org/10.1016/0550-3213(85)90440-7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

20

BECK, CHRISTIAN. « TESTING AXION PHYSICS IN A JOSEPHSON JUNCTION ENVIRONMENT ». Modern Physics Letters A 26, n^o 38 (14 décembre 2011) : 2841–52. http://dx.doi.org/10.1142/s0217732311037248.

Texte intégral

Résumé :

We suggest that experiments based on Josephson junctions, SQUIDS, and coupled Josephson qubits may be used to construct a resonant environment for dark matter axions. We propose experimental setups in which axionic interaction strengths in a Josephson junction environment can be tested, similar in nature to recent experiments that test for quantum entanglement of two coupled Josephson qubits. We point out that the parameter values relevant for early-universe axion cosmology are accessible with present day's achievements in nanotechnology. We work out how typical dark matter and dark energy signals would look like in a novel detector that exploits this effect.

Styles APA, Harvard, Vancouver, ISO, etc.

21

POLLOCK, M. D. « ON THE COSMOLOGY OF THE AXION IN THE HETEROTIC SUPERSTRING THEORY ». International Journal of Modern Physics D 01, n^o 02 (janvier 1992) : 407–25. http://dx.doi.org/10.1142/s0218271892000227.

Texte intégral

Résumé :

The heterotic superstring theory, after reduction to four dimensions, is known to contain two axions, found by Witten, and studied further by Choi and Kim. One combination of these can be identified with the axion of Peccei and Quinn, whose energy scale is then given by the formula [Formula: see text], where [Formula: see text] is the ratio of the two separate energy scales, g s is the strong-interaction coupling constant and M P ≡G−1/2 is the Planck mass, G being the Newton gravitational constant. This agrees with the result obtained by Choi and Kim, apart from a factor of [Formula: see text], which is explained. For a supersymmetric theory, Steinhardt and Turner have shown, developing an idea by Weinberg, that the upper limit on this parameter, corresponding to a closed Universe today, is f a ≲1013ζ9/11≈4×1016 GeV , where ζ≲3×104 is the entropy enhancement accompanying the decay of a supersymmetric particle, presumed to be the gravitino of mass M g ≈104 GeV . These two calculations of f a differ only by a factor of 15 (agreement is obtained for M g ≈106−107 GeV ), suggesting that axions may constitute the dark matter of the Universe. Some further aspects of superstring axions are discussed, including their rôle in the formation of wormholes.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Bakas, Ioannis, Domenico Orlando et Panagiotis Marios Petropoulos. « Ricci flows and expansion in axion-dilaton cosmology ». Journal of High Energy Physics 2007, n^o 01 (9 janvier 2007) : 040. http://dx.doi.org/10.1088/1126-6708/2007/01/040.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

23

Mukherji, Sudipta. « A Note on Brans–Dicke Cosmology with Axion ». Modern Physics Letters A 12, n^o 09 (21 mars 1997) : 639–45. http://dx.doi.org/10.1142/s0217732397000662.

Texte intégral

Résumé :

We study the Brans–Dicke model in the presence of an axion. The dynamical equations are solved when the fields are space-independent and the metric is spatially flat. It is found that at late time the scale factor undergoes decelerated expansion but the dilaton grows large. At early time, scale factor and the dilaton approach constants.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Orlando, Domenico. « Axion-dilaton cosmology, Ricci flows and integrable structures ». Nuclear Physics B - Proceedings Supplements 171 (septembre 2007) : 304–5. http://dx.doi.org/10.1016/j.nuclphysbps.2007.06.041.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

25

Sullivan, James M., Shingo Hirano et Volker Bromm. « Minimum star-forming halo mass in axion cosmology ». Monthly Notices of the Royal Astronomical Society : Letters 481, n^o 1 (3 septembre 2018) : L69—L73. http://dx.doi.org/10.1093/mnrasl/sly164.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

26

Holman, R., et Thomas W. Kephart. « Axion cosmology in automatic E6 × U(1) models ». Physics Letters B 167, n^o 2 (février 1986) : 169–72. http://dx.doi.org/10.1016/0370-2693(86)90593-9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

27

Lyth, David H., et Ewan D. Stewart. « Constraining the inflationary energy scale from axion cosmology ». Physics Letters B 283, n^o 3-4 (juin 1992) : 189–93. http://dx.doi.org/10.1016/0370-2693(92)90006-p.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

Rosenberg, Leslie J. « Dark-matter QCD-axion searches ». Proceedings of the National Academy of Sciences 112, n^o 40 (12 janvier 2015) : 12278–81. http://dx.doi.org/10.1073/pnas.1308788112.

Texte intégral

Résumé :

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 are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Borsanyi, Sz, M. Dierigl, Z. Fodor, S. D. Katz, S. W. Mages, D. Nogradi, J. Redondo, A. Ringwald et K. K. Szabo. « Axion cosmology, lattice QCD and the dilute instanton gas ». Physics Letters B 752 (janvier 2016) : 175–81. http://dx.doi.org/10.1016/j.physletb.2015.11.020.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

30

Maharana, Jnanadeva, Sudipta Mukherji et Sudhakar Panda. « Notes on Axion, Inflation and Graceful Exit in Stringy Cosmology ». Modern Physics Letters A 12, n^o 07 (7 mars 1997) : 447–56. http://dx.doi.org/10.1142/s0217732397000467.

Texte intégral

Résumé :

We study the classical equations of motion and the corresponding Wheeler–De Witt equations for tree level string effective action with dilaton and axion. The graceful exit problem in certain cases is then analyzed.

Styles APA, Harvard, Vancouver, ISO, etc.

31

GUENDELMAN, EDUARDO I., et DORON CHELOUCHE. « RADIO-LOUD MAGNETARS AS DETECTORS FOR AXIONS AND AXION-LIKE PARTICLES ». International Journal of Modern Physics E 20, supp02 (décembre 2011) : 100–108. http://dx.doi.org/10.1142/s0218301311040669.

Texte intégral

Résumé :

We show that, by studying the arrival times of radio pulses from highly-magnetized transient beamed sources, it may be possible to detect light pseudo-scalar particles, such as axions and axion-like particles, whose existence could have considerable implications for the strong-CP problem of QCD as well as the dark matter problem in cosmology. Specifically, such light bosons may be detected with a much greater sensitivity, over a broad particle mass range, than is currently achievable by terrestrial experiments, and using indirect astrophysical considerations. The observable effect was discussed in Chelouche & Guendelman (2009), and is akin to the Stern-Gerlach experiment: the splitting of a photon beam naturally arises when finite coupling exists between the electro-magnetic field and the axion field. The splitting angle of the light beams linearly depends on the photon wavelength, the size of the magnetized region, and the magnetic field gradient in the transverse direction to the propagation direction of the photons. If radio emission in radio-loud magnetars is beamed and originates in regions with strong magnetic field gradients, then splitting of individual pulses may be detectable. We quantify the effect for a simplified model for magnetars, and search for radio beam splitting in the 2GHz radio light curves of the radio loud magnetar XTEJ1810-197.

Styles APA, Harvard, Vancouver, ISO, etc.

32

Choi, Kiwoon, Hang Bae Kim et Jihn E. Kim. « Axion cosmology with a stronger QCD in the early universe ». Nuclear Physics B 490, n^o 1-2 (avril 1997) : 349–64. http://dx.doi.org/10.1016/s0550-3213(97)00066-7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

33

Davidson, Sacha, et Martin Elmer. « Bose-Einstein condensation of the classical axion field in cosmology ? » Journal of Cosmology and Astroparticle Physics 2013, n^o 12 (13 décembre 2013) : 034. http://dx.doi.org/10.1088/1475-7516/2013/12/034.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

34

Barr, S. M., Kiwoon Choi et Jihn E. Kim. « Some aspects of axion cosmology in unified and superstring models ». Nuclear Physics B 283 (janvier 1987) : 591–604. http://dx.doi.org/10.1016/0550-3213(87)90288-4.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Petreczky, Peter, Hans-Peter Schadler et Sayantan Sharma. « The topological susceptibility in finite temperature QCD and axion cosmology ». Physics Letters B 762 (novembre 2016) : 498–505. http://dx.doi.org/10.1016/j.physletb.2016.09.063.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

36

Azcoiti, Vicente. « Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology ». EPJ Web of Conferences 175 (2018) : 04007. http://dx.doi.org/10.1051/epjconf/201817504007.

Texte intégral

Résumé :

The axion is one of the more interesting candidates to make the dark matter of the universe, and the axion potential plays a fundamental role in the determination of the dynamics of the axion field. Moreover, the way in which the U(1)A anomaly manifests itself in the chiral symmetry restored phase of QCD at high temperature could be tested when probing the QCD phase transition in relativistic heavy ion collisions. With these motivations, we investigate the physical consequences of the survival of the effects of the U(1)A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the σ and π susceptibilities diverge in this limit at any T ≥ Tc. We also show that the difference between the π and δ susceptibilities diverges in the chiral limit at any T ≥ Tc, a result that can be contrasted with the existing lattice calculations; and discuss on the generalization of these results to the Nf ≥ 3 model.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Green, Daniel, Yi Guo et Benjamin Wallisch. « Cosmological implications of axion-matter couplings ». Journal of Cosmology and Astroparticle Physics 2022, n^o 02 (1 février 2022) : 019. http://dx.doi.org/10.1088/1475-7516/2022/02/019.

Texte intégral

Résumé :

Abstract Axions and other light particles appear ubiquitously in physics beyond the Standard Model, with a variety of possible couplings to ordinary matter. Cosmology offers a unique probe of these particles as they can thermalize in the hot environment of the early universe for any such coupling. For sub-MeV particles, their entropy must leave a measurable cosmological signal, usually via the effective number of relativistic particles, N eff. In this paper, we will revisit the cosmological constraints on the couplings of axions and other pseudo-Nambu-Goldstone bosons to Standard Model fermions from thermalization below the electroweak scale, where these couplings are marginal and give contributions to the radiation density of ΔN eff > 0.027. We update the calculation of the production rates to eliminate unnecessary approximations and find that the cosmological bounds on these interactions are complementary to astrophysical constraints, e.g. from supernova SN 1987A. We additionally provide quantitative explanations for these bounds and their relationship.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Riechers, Dominik A., Axel Weiss, Fabian Walter, Christopher L. Carilli, Pierre Cox, Roberto Decarli et Roberto Neri. « Water Silhouettes against the Cosmic Microwave Background from the Most Distant Starburst Galaxies ». EPJ Web of Conferences 265 (2022) : 00044. http://dx.doi.org/10.1051/epjconf/202226500044.

Texte intégral

Résumé :

Astrophysical objects can imprint distortions on the observed Cosmic Microwave Background (CMB) that give access to information for cosmology research that cannot be obtained otherwise. ΛCDM cosmology implies a linear scaling of the CMB temperature (TCMB) with redshift z, but departures of this linear scaling behavior are allowed in more complex, but currently poorly observationally constrained cosmological models, such as those that include an evolution of physical constants, decaying dark energy, or axion-photon-like coupling processes. We here introduce a new method to directly measure TCMB out to z > 6 based on H2O absorption against the CMB, and describe our findings based on an initial detection towards the massive dusty starburst galaxy HFLS3 at z=6.34. This far exceeds the redshift range where direct TCMB measurements across cosmic time have been previously possible, providing a crucial test of standard cosmology.

Styles APA, Harvard, Vancouver, ISO, etc.

39

KONISHI, EIJI, et JNANADEVA MAHARANA. « COMPACTIFICATION OF TYPE IIB THEORY WITH FLUXES AND AXION–DILATON STRING COSMOLOGY ». International Journal of Modern Physics A 25, n^o 18n19 (30 juillet 2010) : 3797–816. http://dx.doi.org/10.1142/s0217751x10050111.

Texte intégral

Résumé :

Compactification of type IIB theory on torus, in the presence of fluxes, is considered. The reduced effective action is expressed in manifestly S-duality invariant form. Cosmological solutions of the model are discussed in several cases in the Pre-Big Bang scenario.

Styles APA, Harvard, Vancouver, ISO, etc.

40

POLLOCK, M. D. « ERRATA : ON THE COSMOLOGY OF THE AXION IN THE HETEROTIC SUPERSTRING THEORY ». International Journal of Modern Physics D 05, n^o 04 (août 1996) : 441–43. http://dx.doi.org/10.1142/s0218271896000540.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

41

Klimchitskaya, Galina, Vladimir Mostepanenko, René Sedmik et Hartmut Abele. « Prospects for Searching Thermal Effects, Non-Newtonian Gravity and Axion-Like Particles : Cannex Test of the Quantum Vacuum ». Symmetry 11, n^o 3 (20 mars 2019) : 407. http://dx.doi.org/10.3390/sym11030407.

Texte intégral

Résumé :

We consider the Cannex (Casimir And Non-Newtonian force EXperiment) test of the quantum vacuum intended for measuring the gradient of the Casimir pressure between two flat parallel plates at large separations and constraining parameters of the chameleon model of dark energy in cosmology. A modification of the measurement scheme is proposed that allows simultaneous measurements of both the Casimir pressure and its gradient in one experiment. It is shown that with several improvements the Cannex test will be capable to strengthen the constraints on the parameters of the Yukawa-type interaction by up to an order of magnitude over a wide interaction range. The constraints on the coupling constants between nucleons and axion-like particles, which are considered as the most probable constituents of dark matter, could also be strengthened over a region of axion masses from 1 to 100 meV.

Styles APA, Harvard, Vancouver, ISO, etc.

42

MEI, HSIEN-HAO, WEI-TOU NI, SHENG-JUI CHEN et SHEAU-SHI PAN. « AXION SEARCH WITH Q & ; A EXPERIMENT ». Modern Physics Letters A 25, n^o 11n12 (20 avril 2010) : 983–93. http://dx.doi.org/10.1142/s0217732310000149.

Texte intégral

Résumé :

Dark matter is a focused issue in galactic evolution and cosmology. Axion is a viable particle candidate for dark matter. Its interaction with photon is an effective way to detect it, e.g., pseudoscalar-photon interaction will generate vacuum dichroism in a magnetic field. Motivated to measure the QED vacuum birefringence and to detect pseudoscalar-photon interaction, we started to build up the Q & A experiment (QED [Quantum Electrodynamics] and Axion experiment) in 1994. In this talk, we first give a brief historical account of planet hunting and dark matter evidence. We then review our 3.5 m Fabry-Perot interferometer together with our results of measuring vacuum dichroism and gaseous Cotton-Mouton effects. Our first results give (-0.2 ± 2.8) × 10-13 rad/pass, at 2.3 T with 18,700 passes through a 0.6 m long magnet, for vacuum dichroism measurement. We are upgrading our interferometer to 7 m arm-length with a new 1.8 m 2.3 T permanent magnet capable of rotation up to 13 cycles per second. We aim at [Formula: see text] optical sensitivity with 532 nm cavity finesse around 100,000. When achieved, vacuum dichroism would be measured to 8.6 × 10-17 rad/pass in about 50 days, and QED birefringence would be measured to 28%.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Cain, Christopher, Anson D'Aloisio, Vid Iršič, Nakul Gangolli et Sanya Dhami. « Small-scale clumping of dark matter and the mean free path of ionizing photons at z = 6 ». Journal of Cosmology and Astroparticle Physics 2023, n^o 01 (1 janvier 2023) : 002. http://dx.doi.org/10.1088/1475-7516/2023/01/002.

Texte intégral

Résumé :

Abstract Recently, the mean free path of ionizing photons in the z = 6 intergalactic medium (IGM) was measured to be very short, presenting a challenge to existing reionization models. At face value, the measurement can be interpreted as evidence that the IGM clumps on scales M ≲ 108 M ⊙, a key but largely untested prediction of the cold dark matter (CDM) paradigm. Motivated by this possibility, we study the role that the underlying dark matter cosmology plays in setting the z > 5 mean free path. We use two classes of models to contrast against the standard CDM prediction: (1) thermal relic warm dark matter (WDM), representing models with suppressed small-scale power; (2) an ultralight axion exhibiting a white noise-like power enhancement. Differences in the mean free path between the WDM and CDM models are subdued by pressure smoothing and the possible contribution of neutral islands to the IGM opacity. For example, comparing late reionization scenarios with a fixed volume-weighted mean neutral fraction of 20% at z = 6, the mean free path is 19 (45)% longer in a WDM model with mx = 3 (1) keV. The enhanced power in the axion-like model produces better agreement with the short mean free path measured at z = 6. However, drawing robust conclusions about cosmology is hampered by large uncertainties in the reionization process, extragalactic ionizing background, and thermal history of the Universe. This work highlights some key open questions about the IGM opacity during reionization.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Biteau, Jonathan, et Manuel Meyer. « Gamma-Ray Cosmology and Tests of Fundamental Physics ». Galaxies 10, n^o 2 (22 février 2022) : 39. http://dx.doi.org/10.3390/galaxies10020039.

Texte intégral

Résumé :

The propagation of gamma-rays over cosmological distances is the subject of extensive theoretical and observational research at GeV and TeV energies. The mean free path of gamma-rays in the cosmic web is limited above 100 GeV due to the production of electrons and positrons on the cosmic optical and infrared backgrounds. Electrons and positrons cool in the intergalactic medium while gyrating in its magnetic fields, which could cause either its global heating or the production of lower-energy secondary gamma-rays. The energy distribution of gamma-rays surviving the cosmological journey carries observed absorption features that gauge the emissivity of baryonic matter over cosmic time, constrain the distance scale of ΛCDM cosmology, and limit the alterations of the interaction cross section. Competitive constraints are, in particular, placed on the cosmic star-formation history as well as on phenomena expected from quantum gravity and string theory, such as the coupling to hypothetical axion-like particles or the violation of Lorentz invariance. Recent theoretical and observational advances offer a glimpse of the multi-wavelength and multi-messenger path that the new generation of gamma-ray observatories is about to open.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Berezhiani, Z. G., et M. Yu Khlopov. « Cosmology of spontaneously broken gauge family symmetry with axion solution of strong CP-problem ». Zeitschrift für Physik C Particles and Fields 49, n^o 1 (mars 1991) : 73–78. http://dx.doi.org/10.1007/bf01570798.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

46

Hashiba, Soichiro, Kohei Kamada et Hiromasa Nakatsuka. « Gauge field production and Schwinger reheating in runaway axion inflation ». Journal of Cosmology and Astroparticle Physics 2022, n^o 04 (1 avril 2022) : 058. http://dx.doi.org/10.1088/1475-7516/2022/04/058.

Texte intégral

Résumé :

Abstract In a class of (pseudoscalar) inflation, inflationary phase is followed by a kination phase, where the Universe is dominated by the kinetic energy of the inflaton that runs away in a vanishing scalar potential. In this class of postinflationary evolution of the Universe, reheating of the Universe cannot be achieved by the inflaton particle decay, which requires its coherent oscillation in a quadratic potential. In this study, we explore the U(1) gauge field production through the Chern-Simons coupling between the pseudoscalar inflaton and the gauge field during the kination era and examine the subsequent pair-particle production induced by the amplified gauge field known as the Schwinger effect, which can lead to reheating of the Universe. We find that with a rough estimate of the Schwinger effect for the Standard Model hyper U(1) gauge field and subsequent thermalization of the pair-produced particles, a successful reheating of the Universe can be achieved by their eventual domination over the kinetic energy of the inflaton, with some reasonable parameter sets. This can be understood as a concrete realization of the “Schwinger reheating”. Constraints from the later-time cosmology are also discussed.

Styles APA, Harvard, Vancouver, ISO, etc.

47

DAS, C. R., et L. V. LAPERASHVILI. « MIRROR WORLD WITH BROKEN MIRROR PARITY, E6 UNIFICATION AND COSMOLOGY ». International Journal of Modern Physics A 23, n^o 12 (10 mai 2008) : 1863–90. http://dx.doi.org/10.1142/s0217751x08039712.

Texte intégral

Résumé :

In the present paper we develop a concept of parallel ordinary (O) and mirror (M) worlds. We have shown that in the case of a broken mirror parity (MP), the evolutions of fine structure constants in the O- and M-worlds are not identical. It is assumed that E6-unification inspired by superstring theory restores the broken MP at the scale ~ 1018 GeV , what unavoidably leads to the different E6-breakdowns at this scale: E6 → SO (10) × U (1)Z — in the O-world, and E′6 → SU (6)′ × SU (2)′Z — in the M-world. Considering only asymptotically free theories, we have presented the running of all the inverse gauge constants [Formula: see text] in the one-loop approximation. Then a "quintessence" scenario suggested in Refs. 56–61 is discussed for our model of accelerating universe. Such a scenario is related with an axion ("acceleron") of a new gauge group SU (2)′Z which has a coupling constant gZ extremely growing at the scale ΛZ ~ 10-3 eV .

Styles APA, Harvard, Vancouver, ISO, etc.

48

Choudhury, Sayantan, et Sudhakar Panda. « Cosmological Spectrum of Two-Point Correlation Function from Vacuum Fluctuation of Stringy Axion Field in De Sitter Space : A Study of the Role of Quantum Entanglement ». Universe 6, n^o 6 (5 juin 2020) : 79. http://dx.doi.org/10.3390/universe6060079.

Texte intégral

Résumé :

In this work, we study the impact of quantum entanglement on the two-point correlation function and the associated primordial power spectrum of mean square vacuum fluctuation in a bipartite quantum field theoretic system. The field theory that we consider is the effective theory of axion field arising from Type IIB string theory compacted to four dimensions. We compute the expression for the power spectrum of vacuum fluctuation in three different approaches, namely (1) field operator expansion (FOE) technique with the quantum entangled state, (2) reduced density matrix (RDM) formalism with mixed quantum state and (3) the method of non-entangled state (NES). For a massless axion field, in all three formalisms, we reproduce, at the leading order, the exact scale invariant power spectrum which is well known in the literature. We observe that due to quantum entanglement, the sub-leading terms for these thee formalisms are different. Thus, such correction terms break the degeneracy among the analysis of the FOE, RDM and NES formalisms in the super-horizon limit. On the other hand, for massive axion field we get a slight deviation from scale invariance and exactly quantify the spectral tilt of the power spectrum in small scales. Apart from that, for massless and massive axion field, we find distinguishable features of the power spectrum for the FOE, RDM, and NES on the large scales, which is the result of quantum entanglement. We also find that such large-scale effects are comparable to or greater than the curvature radius of the de Sitter space. Most importantly, in near future if experiments probe for early universe phenomena, one can detect such small quantum effects. In such a scenario, it is possible to test the implications of quantum entanglement in primordial cosmology.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Westphal, Alexander. « String cosmology — Large-field inflation in string theory ». International Journal of Modern Physics A 30, n^o 09 (25 mars 2015) : 1530024. http://dx.doi.org/10.1142/s0217751x15300240.

Texte intégral

Résumé :

This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index ns and the fractional tensor mode power r. Hence, we will focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Burigana, Carlo, Elia Stefano Battistelli, Micol Benetti, Giovanni Cabass, Paolo De Bernardis, Sperello Di Serego Alighieri, Eleonora Di Valentino et al. « Recent results and perspectives on cosmology and fundamental physics from microwave surveys ». International Journal of Modern Physics D 25, n^o 06 (mai 2016) : 1630016. http://dx.doi.org/10.1142/s0218271816300160.

Texte intégral

Résumé :

Recent cosmic microwave background (CMB) data in temperature and polarization have reached high precision in estimating all the parameters that describe the current so-called standard cosmological model. Recent results about the integrated Sachs–Wolfe (ISW) effect from CMB anisotropies, galaxy surveys, and their cross-correlations are presented. Looking at fine signatures in the CMB, such as the lack of power at low multipoles, the primordial power spectrum (PPS) and the bounds on non-Gaussianities, complemented by galaxy surveys, we discuss inflationary physics and the generation of primordial perturbations in the early universe. Three important topics in particle physics, the bounds on neutrinos masses and parameters, on thermal axion mass and on the neutron lifetime derived from cosmological data are reviewed, with attention to the comparison with laboratory experiment results. Recent results from cosmic polarization rotation (CPR) analyses aimed at testing the Einstein equivalence principle (EEP) are presented. Finally, we discuss the perspectives of next radio facilities for the improvement of the analysis of future CMB spectral distortion experiments.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Axion cosmology »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres