Effects of quantum statistics on relic density of Dark Radiation

TL;DR

This paper examines how quantum statistics influence the relic density of dark radiation by analyzing massless particle freeze-out, comparing Boltzmann solutions with approximations, and applying findings to Weinberg's Higgs portal model.

Contribution

It provides a detailed analysis of quantum statistical effects on massless particle freeze-out and applies these results to dark radiation in a specific theoretical model.

Findings

Quantum statistics significantly affect relic density calculations.

Comparison shows differences between Boltzmann solutions and approximate methods.

Results applied to dark radiation in Weinberg's Higgs portal model.

Abstract

The freeze-out of massless particles is investigated. The effects due to quantum statistics, Fermi-Dirac or Bose-Einstein, of all particles relevant for the process are analyzed. Solutions of appropriate Boltzmann equation are compared with those obtained using some popular approximate methods. As an application of general results the relic density of dark radiation in Weinberg's Higgs portal model is discussed.