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

Authors:
Preprint
Publisher website
Google Scholar
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. If the scalar is a singlet, then the main correction arises from the fact that the effective mass of the decaying particle is temperature dependent. If the scalar has gauge interactions, then at least one of the decay products must also carry gauge quantum numbers and will be in thermal equilibrium in the early universe. This gives rise to Pauli blocking and a modification of the dispersion relation of these charged particles in the plasma, which affects the kinematics of the decay. Moreover, at high temperature, inelastic scatterings can contribute to the singlet fermion production rate. As a result, the production rate of singlet fermions has a non-trivial temperature dependence. This can affect the abundance and momentum distribution of sterile neutrino Dark Matter that is produced in scalar decays. Our results can be used to improve predictions for the free streaming of the Dark Matter particles, which is crucial to test the compatibility of such scenarios with cosmic structure formation.

This publication has 94 references indexed in Scilit: