Abstract
Abstract
Exponential suppression or commonly known as the Boltzmann suppression in the number density of dark matter is the key ingredient for creating chemical imbalance prior to the usual thermal freeze-out. A degenerate/quasi-degenerate dark sector can experience a different exponential suppression in the number density analogous to the radioactive decay law leading to a delayed freeze-out mechanism of dark matter known as the co-decaying dark matter. In this work, we study the dynamics of a multicomponent dark matter from thermally decoupled degenerate dark sector in a hidden U(1)X extension of the Standard Model. We compute the relic density of dark matter frozen-out through the co-decaying mechanism by solving four coupled Boltzmann equations. We demonstrate how temperature T′ of the dark sector changes due to all types of 3 → 2 and 2 → 2 interactions along with the eternal expansion of the Universe. We find that 3 → 2 interactions enhance T′ by producing energetic particles in the dark sector while the excess heat is transferred by 2 → 2 interactions to the entire dark sector. As the direct detection is possible only through the feeble portal couplings, we investigate the neutrino and γ-ray signals from dark matter annihilation via one step cascade processes and compare our results with the measured fluxes of atmospheric neutrinos by Super-Kamiokande and diffuse γ-rays by Fermi-LAT, EGRET, INTEGRAL collaborations. We find that the present scenario easily evades all the existing bounds from atmospheric neutrino and diffuse γ-ray observations for degenerate dark sector. However, the constraints are significant for quasi degenerate scenario.
Publisher
Springer Science and Business Media LLC
Subject
Nuclear and High Energy Physics
Reference90 articles.
1. WMAP collaboration, Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results, Astrophys. J. Suppl. 208 (2013) 19 [arXiv:1212.5226] [INSPIRE].
2. Planck collaboration, Planck 2018 results. VI. Cosmological parameters, Astron. Astrophys. 641 (2020) A6 [arXiv:1807.06209] [INSPIRE].
3. Y. Sofue and V. Rubin, Rotation curves of spiral galaxies, Ann. Rev. Astron. Astrophys. 39 (2001) 137 [astro-ph/0010594] [INSPIRE].
4. M. Bartelmann and P. Schneider, Weak gravitational lensing, Phys. Rept. 340 (2001) 291 [astro-ph/9912508] [INSPIRE].
5. D. Clowe et al., A direct empirical proof of the existence of dark matter, Astrophys. J. Lett. 648 (2006) L109 [astro-ph/0608407] [INSPIRE].
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