Primordial He' abundance implied by the mirror dark matter interpretation of the DAMA/Libra signal

TL;DR

This paper calculates the primordial mirror helium abundance from Big Bang nucleosynthesis considering photon-mirror photon kinetic mixing, finding a high helium fraction relevant for dark matter detection and mirror star evolution.

Contribution

It provides the first detailed computation of mirror helium abundance in the context of kinetic mixing parameters relevant for current dark matter experiments.

Findings

High mirror helium fraction (~90%) for kinetic mixing epsilon ~ 10^{-9}

Implications for mirror dark matter detection and mirror star formation

Supports the mirror dark matter interpretation of DAMA/Libra results

Abstract

We compute the primordial mirror helium He' mass fraction emerging from Big Bang nucleosynthesis in the mirror sector of particles in the presence of kinetic mixing between photons and mirror photons. We explore the kinetic mixing parameter (epsilon) values relevant for cosmology and which are also currently probed by the dark matter direct detection experiments. In particular, we find that for epsilon \sim 10^{-9}, as suggested by the DAMA/Libra and other experiments, a large He' mass fraction (Y_{He'} \approx 90%) is produced. Such a large value of the primordial He' mass fraction will have important implications for the mirror dark matter interpretation of the direct detection experiments, as well as for the study of mirror star formation and evolution.