Sterile neutrino Dark Matter production from scalar decay in a thermal bath

TL;DR

This paper calculates the production rate of sterile neutrino dark matter from scalar decays in a hot plasma, incorporating thermal corrections to improve predictions of dark matter abundance and distribution.

Contribution

It provides analytic and numerical results for thermal corrections to sterile neutrino production rates from scalar decays, enhancing dark matter modeling accuracy.

Findings

Thermal corrections are significant at high temperatures.

Analytic expressions for relativistic decay products are derived.

Numerical analysis covers non-relativistic decay regimes.

Abstract

We calculate the production rate of singlet fermions from the decay of neutral or charged scalar fields in a hot plasma. We find that there are considerable thermal corrections when the temperature of the plasma exceeds the mass of the decaying scalar. We give analytic expressions for the temperature-corrected production rates in the regime where the decay products are relativistic. We also study the regime of non-relativistic decay products numerically. Our results can be used to determine the abundance and momentum distribution of Dark Matter particles produced in scalar decays. The inclusion of thermal corrections helps to improve predictions for the free streaming of the Dark Matter particles, which is crucial to test the compatibility of a given model with cosmic structure formation. With some modifications, our results may be generalised to the production of other Dark Matter candidates in scalar decays.