A tower of hidden sectors: a general treatment and physics implications

TL;DR

This paper develops a formalism for analyzing a chain of hidden sectors coupled to each other and the visible sector, exploring their thermal evolution and implications for dark matter detection and cosmology.

Contribution

It introduces a general framework with coupled Boltzmann equations for multiple hidden sectors, including their interactions and thermal histories.

Findings

Predictions for dark matter direct detection experiments.

Implications for future CMB probes of dark radiation.

A formalism for coupled thermal evolution of hidden sectors.

Abstract

An analysis of a tower of hidden sectors coupled to each other, with one of these hidden sectors coupled to the visible sector, is given and the implications of such couplings on physics in the visible sector are investigated. Thus the analysis considers $n$ number of hidden sectors where the visible sector couples only to hidden sector 1, while the latter couples also to hidden sector 2, and the hidden sector 2 couples to hidden sector 3 and so on. A set of successively feeble couplings of the hidden sectors to the visible sector are generated in such a set up. In general each of these sectors live in a different heat bath. We develop a closed form set of coupled Boltzmann equations for the correlated evolution of the temperatures and number densities of each of the heat baths. We then apply the formalism to a simplified model with scalar portals between the different sectors. Predictions related to dark matter direct detection experiments and future CMB probes of dark radiation are made.