The ALP miracle: unified inflaton and dark matter

By Ryuji Daido, F. Takahashi, W. Yin. 2017

153 citations recorded by the source corpus.

We propose a scenario where both inflation and dark matter are described by a single axion-like particle (ALP) in a unified manner. In a class of the minimal axion hilltop inflation, the effective masses at the maximum and mimimum of the potential have equal magnitude but opposite sign, so that the ALP inflaton is light both during inflation and in the true vacuum. After inflation, most of the ALPs decay and evaporate into plasma through a coupling to photons, and the remaining ones become dark matter. We find that the observed CMB and matter power spectrum as well as the dark matter abundance point to an ALP of mass mϕ = 𝒪(0.01) eV and the axion-photon coupling gϕ γ γ = 𝒪(10−11) GeV−1: the ALP miracle. The suggested parameter region is within the reach of the next generation axion helioscope, IAXO, and high-intensity laser experiments in the future. Furthermore, thermalized ALPs contribute to hot dark matter and its abundance is given in terms of the effective number of extra neutrino species, Δ Neff ≃ 0.03, which can be tested by the future CMB and BAO observations. We also discuss a case with multiple ALPs, where the coupling to photons can be enhanced in the early Universe by an order of magnitude or more, which enlarges the parameter space for the ALP miracle. The heavy ALP plays a role of the waterfall field in hybrid inflation, and reheats the Universe, and it can be searched for in various experiments such as SHiP.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0c5f7b25fc50d081f3c69eee03114f58ff2cb155

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Citations in the corpus

QCD axion window and low-scale inflation (2018, background): “In particular, Daido and two of the present authors (FT and WY) recently studied an inflation model where an axion-like particle plays the role of both the inflaton and dark matter [61,62].”
Physics potential of the International Axion Observatory (IAXO) (2019, background): “Thus, the Planck normalization of curvature perturbation and the observed spectral index determine the relation between the decay constant and the axion mass [189, 192]”
New experimental approaches in the search for axion-like particles (2018, background): “Perhaps one exception is the so-called ALP-miracle model of [316,317] where an ALP with two cosine potentials giving something like a Hilltop quartic potential can drive inflation, reheat through the coupling to photons gaγ ∼ 10−11GeV−1 and provide the DM of the Universe through the realignment mech”