Axion Kinetic Misalignment Mechanism

Co, Raymond T.; Hall, Lawrence J.; Harigaya, Keisuke

doi:10.1103/physrevlett.124.251802

Cited by 162 publications

(232 citation statements)

References 74 publications

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“…Note added.-Recently, Ref. [25] (as also noted in the introduction) came out which has overlap with our results. The two papers are complementary to each other as explained in the introduction.…”

Section: Discussionsupporting

confidence: 77%

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New perspectives on axion misalignment mechanism

Chang

Cui

2020

Phys. Rev. D

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A zero initial velocity of the axion field is assumed in the conventional misalignment mechanism. We propose an alternative scenario where the initial velocity is nonzero, which may arise from an explicit breaking of the Peccei-Quinn (PQ) symmetry in the early Universe. We demonstrate that, depending on the specifics of the initial velocity and the time order of the PQ symmetry breaking vs inflation, this new scenario can either enhance or suppress the axion relic abundance relative to the conventional prediction. As a result, new viable parameter regions for axion dark matter may open up.

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Section: Discussionsupporting

confidence: 77%

“…An example model realizing such an initial condition is illustrated in Appendix B. Another recent work [25] also considered the possibility of _ θ i ≠ 0, focusing on the large _ θ > 0 region, demonstrating examples of interesting UV complete models leading to an enhanced Ω a .…”

Section: Introductionmentioning

confidence: 99%

New perspectives on axion misalignment mechanism

Chang

Cui

2020

Phys. Rev. D

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“…Our mechanism depends on the mass m a and decay constant f a of the ALP, together with the comoving charge density associated with the broken U(1) symmetry, Y θ ∝θ. Dark matter is composed of a condensate of zero momentum ALPs produced by the kinetic misalignment mechanism [9] with an energy density to entropy ratio of ρ a s 2m a Y θ . (1.1)…”

Section: Jhep01(2021)172mentioning

confidence: 99%

“…The baryon and dark matter number densities are both proportional toθ, which drops out of the ratio. In this paper, we do not analyze in detail the cosmological evolution of P in various models, as we have done this elsewhere for both quadratic and quartic potentials [9]. In general, a relatively flat potential for S is needed, together with a large initial field value, for example from inflation.…”

Section: Jhep01(2021)172mentioning

confidence: 99%

Predictions for axion couplings from ALP cogenesis

Hall

Harigaya

2021

J. High Energ. Phys.

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Adding an axion-like particle (ALP) to the Standard Model, with a field velocity in the early universe, simultaneously explains the observed baryon and dark matter densities. This requires one or more couplings between the ALP and photons, nucleons, and/or electrons that are predicted as functions of the ALP mass. These predictions arise because the ratio of dark matter to baryon densities is independent of the ALP field velocity, allowing a correlation between the ALP mass, ma, and decay constant, fa. The predicted couplings are orders of magnitude larger than those for the QCD axion and for dark matter from the conventional ALP misalignment mechanism. As a result, this scheme, ALP cogenesis, is within reach of future experimental ALP searches from the lab and stellar objects, and for dark matter.

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“…It is known that throughout the cosmological history, axions may form gravitationally-bound objects, whose density can be orders of magnitude larger than the local dark matter density. Typical examples include axion miniclusters [23,24] and boson stars [25][26][27] (see also [28][29][30][31] for recent discussions). Being much denser than the average galactic DM density, these small-scale objects could boost the discovery potential of aforementioned axion dark matter experiments, should they exist.…”

Section: Introductionmentioning

confidence: 99%

Searching for Earth/Solar axion halos

Banerjee

Budker

Eby

et al. 2020

J. High Energ. Phys.

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We discuss the sensitivity of the present and near-future axion dark matter experiments to a halo of axions or axion-like particles gravitationally bound to the Earth or the Sun. Such halos, assuming they are formed, can be searched for in a wide variety of experiments even when the axion couplings to matter are small, while satisfying all the present experimental bounds on the local properties of dark matter. The structure and coherence properties of these halos also imply novel signals, which can depend on the latitude or orientation of the detector. We demonstrate this by analyzing the sensitivity of several distinct types of axion dark matter experiments.

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Axion Kinetic Misalignment Mechanism

Cited by 162 publications

References 74 publications

New perspectives on axion misalignment mechanism

New perspectives on axion misalignment mechanism

Predictions for axion couplings from ALP cogenesis

Searching for Earth/Solar axion halos

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