$Z^\prime$-mediated dark matter freeze-in at stronger coupling

TL;DR

This paper investigates a dark matter production mechanism via a $Z'$ gauge boson at strong coupling, highlighting its potential detectability through current and future experiments.

Contribution

It introduces a freeze-in dark matter model mediated by $Z'$ with strong coupling, focusing on Boltzmann-suppressed production regimes.

Findings

Dark matter can be produced via $Z'$ mediation at strong coupling.

The model's parameter space is accessible to direct detection experiments.

Boltzmann suppression plays a key role in the production process.

Abstract

We study freeze-in production of fermionic dark matter mediated by a $Z^\prime$ gauge boson. In particular, we explore the regime of Boltzmann-suppressed production, when the Standard Model (SM) thermal bath temperature never exceeds the dark matter mass. The corresponding gauge coupling is then required to be significant, up to order one. As a result, this class of freeze-in models can be probed by the current and future direct dark matter detection experiments.