A multi-temperature universe can allow a sub-MeV dark photon dark matter

TL;DR

This paper explores the possibility of sub-MeV dark photon dark matter within a multi-temperature universe framework involving two hidden sectors with different interactions, providing a formalism for their thermal evolution.

Contribution

It introduces a formalism for the evolution of three bath temperatures in a universe with multiple hidden sectors and applies it to analyze sub-MeV dark photon dark matter.

Findings

Exclusion plots showing viable parameter space for dark photon dark matter.

Development of a formalism for multi-temperature evolution in multi-sector universes.

Demonstration that sub-MeV dark photons can constitute dark matter under certain conditions.

Abstract

An analysis of sub-MeV dark photon as dark matter is given which is achieved with two hidden sectors, one of which interacts directly with the visible sector while the second has only indirect coupling with the visible sector. The formalism for the evolution of three bath temperatures for the visible sector and the two hidden sectors is developed and utilized in solution of Boltzmann equations coupling the three sectors. We present exclusion plots where the sub-MeV dark photon can be dark matter. The analysis can be extended to a multi-temperature universe with multiple hidden sectors and multiple heat baths.