Freeze-in Dark Matter Through Forbidden Channel in $U(1)_{B-L}$

TL;DR

This paper investigates a novel freeze-in dark matter production mechanism via forbidden channels in the early Universe, emphasizing the role of thermal corrections in a $U(1)_{B-L}$ model, and compares it to standard scenarios.

Contribution

It introduces a new forbidden channel mechanism for freeze-in dark matter production, highlighting the impact of thermal mass corrections in the $U(1)_{B-L}$ model.

Findings

Forbidden decay channels become significant at high temperatures.

Thermal corrections enable otherwise kinematically forbidden decays.

The model's dark matter phenomenology differs from standard freeze-in scenarios.

Abstract

We examine a scenario for freeze-in production of dark matter, which occurs due to the large thermal correction to the mass of a decaying mediator particle present in the thermal bath of the early Universe. We show that the decays, which are kinematically forbidden otherwise, can open up at very high temperatures and dominate the dark matter production. We explore such forbidden production of dark matter in the minimal $U(1)_{B-L}$ model, comparing dark matter phenomenology in the context of forbidden frozen-in with the standard picture.