Scrutinizing Fermionic Dark Matter in Scotogenic Model with Low Reheating Temperature

TL;DR

This paper explores how a low reheating temperature in the early universe affects fermionic dark matter in the scotogenic model, highlighting the potential for upcoming experiments to test this scenario.

Contribution

It demonstrates that low reheating temperatures can significantly alter dark matter relic abundance calculations, expanding the viable parameter space and guiding future experimental searches.

Findings

Entropy injection dilutes dark matter abundance.

Next-generation experiments can probe low reheating temperature scenarios.

Viable parameter space is enlarged under low reheating conditions.

Abstract

The scotogenic model provides a minimal and elegant framework that simultaneously explains neutrino masses and accommodates a viable dark matter (DM) candidate. In this work, we investigate the phenomenology of fermionic DM in the scotogenic model, with a particular emphasis on the effects of a non-standard cosmological history characterized by a low reheating temperature. We demonstrate that entropy injection from inflaton decay can significantly dilute the DM abundance, thereby relaxing the annihilation cross section required to reproduce the observed relic density and opening new regions of viable parameter space. We further analyze the complementarity between current and future direct detection experiments and charged lepton flavour violation (cLFV) searches in probing this scenario. Our results show that next-generation direct detection experiments such as DARWIN and XLZD, together with upcoming cLFV searches (in particular the future sensitivity of $\mu \rightarrow 3e$ and $\mu \rightarrow e$ conversion experiments), will be capable of testing substantial regions of the parameter space, including those associated with low reheating temperatures.