• Open Access

Momentum distribution of dark matter produced in inflaton decay: Effect of inflaton mediated scatterings

Avirup Ghosh and Satyanarayan Mukhopadhyay
Phys. Rev. D 106, 043519 – Published 10 August 2022

Abstract

Postinflationary reheating is a widely discussed mechanism for nonthermal production of dark matter (DM). In this scenario the momentum distribution of the produced DM particles is usually taken to be the one obtained at reheating, redshifted at later times due to the expansion of the Universe. However, since in such a scenario both the DM and the standard model (SM) fields couple to the inflaton, the DM particles necessarily undergo self-scatterings, as well as elastic and inelastic scattering reactions with the SM bath, all of which proceed through s-channel or t-channel inflaton exchange. We compute the momentum distribution of the DM particles including the effect of these scatterings, and find that the distributions can be significantly altered, even though DM remains nonthermal throughout the cosmological evolution. We observe that if the inflaton dominantly couples to the SM Higgs boson through a renormalizable interaction, then reheating temperatures and inflaton masses at the TeV scale lead to a large effect from the scattering processes, with the DM-inflaton coupling constrained by the DM density. The scattering effects are found to be sensitive to the duration of the reheating process—larger the duration, more momentum modes are filled at reheating, leading to an enhanced scattering probability. We also obtain the free-streaming length of such DM using the resulting nonthermal momentum distribution, which can be used to estimate the implications of the Lyman-α constraints on the DM mass. It is observed that in the scenarios considered, including the scattering effects can reduce the DM average velocity at matter-radiation equality, and its free-streaming length, by up to a factor of 40, thereby making the constraints on light DM produced in inflaton decay significantly weaker.

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  • Received 18 May 2022
  • Accepted 25 July 2022

DOI:https://doi.org/10.1103/PhysRevD.106.043519

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Avirup Ghosh* and Satyanarayan Mukhopadhyay

  • School of Physical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Kolkata 700 032, India

  • *spsag2510@iacs.res.in
  • tpsnm@iacs.res.in

Article Text

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Issue

Vol. 106, Iss. 4 — 15 August 2022

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