Temperature effects on the $Z_2$ symmetry breaking in the scotogenic model

TL;DR

This paper investigates the impact of temperature on $Z_2$ symmetry breaking in the scotogenic model, showing that previous constraints are not valid when heavy particle decoupling is properly considered.

Contribution

It demonstrates that temperature-induced $Z_2$ symmetry constraints are not restrictive in the perturbative regime when heavy particle decoupling is accurately included.

Findings

No constraints on parameter space from $Z_2$ breaking at high temperatures.

Proper decoupling of heavy degrees of freedom is crucial for accurate analysis.

Previous claims of constraints are invalid under correct decoupling assumptions.

Abstract

It is well-known that the scotogenic model for neutrino mass generation can explain correctly the relic abundance of cold dark matter. There have been claims in the literature that an important part of the parameter space of the simplest scotogentic model can be constrained by the requirement that no $Z_2$-breaking must occur in the early universe. Here we show that this requirement does not give any constraints on the underlying parameter space at least in those parts, where we can trust perturbation theory. To demonstrate this, we have taken into account the proper decoupling of heavy degrees of freedom in both, the thermal potential and in the RGE evolution.