Cosmological perturbations of axion with a dynamical decay constant

Kobayashi, T.; Takahashi, Fuminobu

doi:10.1088/1475-7516/2016/08/056

Cited by 6 publications

(4 citation statements)

References 67 publications

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“…Note also that, as long as the PQ symmetry is never restored after inflation, the variance of the misalignment angle distribution at large scales is preserved until the onset of the oscillations of the ALP. At small scales, on the other hand, the axion fluctuation gets enhanced as the effective decay constant decreases, which will also help to form domain walls without strings [72]. As a consequence, the condition (2.2) or (2.3) is naturally satisfied in this set-up, and domain walls without strings can be formed.…”

Section: Jcap04(2021)007mentioning

confidence: 90%

Kilobyte Cosmic Birefringence from ALP domain walls

Takahashi

Yin

2021

J. Cosmol. Astropart. Phys.

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ALP domain walls without strings may be formed in the early Universe. We point out that such ALP domain walls lead to both isotropic and anisotropic birefringence of cosmic microwave background (CMB) polarization, which reflects spatial configuration of the domain walls at the recombination. The polarization plane of the CMB photon coming from each domain is either not rotated at all or rotated by a fixed angle. For domain walls following the scaling solution, the cosmic birefringence of CMB is characterized by 2 N , i.e. N-bit, of information with N = 𝒪(103-4) being equal to the number of domains at the last scattering surface, and thus the name, kilobyte cosmic birefringence. The magnitude of the isotropic birefringence is consistent with the recently reported value, while the anisotropic one is determined by the structure of domains at the last scattering surface. The predicted cosmic birefringence is universal over a wide range of the ALP mass and coupling to photons. The detection of both signals will be a smoking-gun evidence for the ALP domain walls without strings.

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Section: Jcap04(2021)007mentioning

confidence: 90%

Kilobyte Cosmic Birefringence from ALP domain walls

Takahashi

Yin

2021

J. Cosmol. Astropart. Phys.

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“…of the QCD axion) or f a (e.g. [39,43,44,45,46,47]) can also modify the cosmological evolution of the axion.…”

Section: Comments On Axion-like Fieldsmentioning

confidence: 99%

Lyman- α constraints on ultralight scalar dark matter: Implications for the early and late universe

et al. 2017

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We investigate constraints on scalar dark matter (DM) by analyzing the Lyman-α forest, which probes structure formation at medium and small scales, and also by studying its cosmological consequences at high and low redshift. For scalar DM that constitutes more than 30% of the total DM density, we obtain a lower limit m 10 −21 eV for the mass of scalar DM. This implies an upper limit on the initial field displacement (or the decay constant for an axion-like field) of φ 10 16 GeV. We also derive limits on the energy scale of cosmic inflation and establish an upper bound on the tensor-to-scalar ratio of r < 10 −3 in the presence of scalar DM. Furthermore, we show that there is very little room for ultralight scalar DM to solve the "small-scale crisis" of cold DM without spoiling the Lyman-α forest results. The constraints presented in this paper can be used for testing generic theories that contain light scalar fields.

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“…In the sub-horizon relativistic regime, the NG boson (i.e., the phase direction of the Higgs field) has a nonzero rotational velocity in the phase space. When the radial direction of the Higgs field decrease over time, the rotational velocity of the NG boson increase because of the conservation of angular momentum in the phase space [35]. This results in the relative enhancement of the longitudinal modes of the dark photon, which implies that a mode with a larger wavenumber grows over a longer time, so that the resulting spectrum has a peak at a large wavenumber.…”

Section: Discussionmentioning

confidence: 99%

Gravitational production of dark photon dark matter with mass generated by the Higgs mechanism

Sato

Takahashi

Yamada

2022

J. Cosmol. Astropart. Phys.

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We study the gravitational production of dark photon dark matter during inflation, when dark photons acquire mass by the Higgs mechanism. In the previous study, it was assumed that the dark photon has a Stückelberg mass, or a mass generated by the Higgs mechanism with a sufficiently heavy Higgs boson. In this paper we consider a case in which the Higgs boson is not fully decoupled; the Higgs field changes its vacuum expectation value after inflation. Then, the dark photon mass also changes with time after inflation, and the time evolution of the longitudinal mode is different from the case with a Stückelberg mass. Consequently, the spectrum of the dark photon energy density can have two peaks at an intermediate scale and a small scale. We show that the dark photon can explain the dark matter if its current mass is larger than 6 μeV × (HI /1014 GeV)-4 and smaller than 0.8 GeV × (HI /1014 GeV)-3/2, with HI being the Hubble parameter during inflation. A higher mass is required if one considers a larger gauge coupling constant. The result for the Stückelberg mass can be reproduced in the limit of a small gauge coupling constant. We also comment on the constraints set by various conjectures in quantum gravity theory.

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Cosmological perturbations of axion with a dynamical decay constant

Cited by 6 publications

References 67 publications

Kilobyte Cosmic Birefringence from ALP domain walls

Kilobyte Cosmic Birefringence from ALP domain walls

Lyman- α constraints on ultralight scalar dark matter: Implications for the early and late universe

Gravitational production of dark photon dark matter with mass generated by the Higgs mechanism

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