Cosmology with Long-Lived Charged Massive Particles

TL;DR

This paper studies the cosmological impact of long-lived charged massive particles (CHAMPs), focusing on their bound states with light elements, and derives constraints from matter power spectrum suppression.

Contribution

It provides a detailed numerical analysis of CHAMP bound state evolution and identifies the large scale structure constraint as the most stringent limit.

Findings

Most negative CHAMPs are captured by He4 forming charged bound states.

Charged bound states suppress matter density fluctuations due to acoustic damping.

Large scale structure constraints are the strongest among cosmological bounds.

Abstract

We investigate the evolution of the bound state of negatively charged massive particles (CHAMPs) with light elements and discuss its cosmological consequences and the constraint. By numerically solving the Boltzmann equation, we study the time evolutions of such bound states. Since most of negative CHAMPs are captured by He4, its bound state is positively charged and couples with the electromagnetic plasma. When charged particles constitute a dominant non-relativistic component, density fluctuations of matter cannot grow due to the acoustic damping. This results in the suppression of matter power spectrum from which a severe constraint can be obtained. By arguing constraints from other aspects of cosmology, we show that the constraint from large scale structure gives most stringent one in some representative cases.