Leptogenesis, Z' bosons, and the reheating temperature of the Universe

TL;DR

This paper investigates how new U(1) gauge bosons (Z') influence leptogenesis, showing they can enhance efficiency and alter the minimum reheating temperature needed for successful baryogenesis.

Contribution

It demonstrates the impact of Z' bosons on leptogenesis efficiency and determines the parameter space and reheating temperature constraints.

Findings

Z' bosons can significantly boost leptogenesis efficiency in the weak washout regime.

The allowed parameter space for leptogenesis is expanded with the presence of Z' bosons.

A minimum reheating temperature is identified for successful leptogenesis with Z' bosons.

Abstract

We study the impact for leptogenesis of new U(1) gauge bosons coupled to the heavy Majorana neutrinos. They can significantly enhance the efficiency of thermal scenarios in the weak washout regime as long as the Z' masses are not much larger than the reheating temperature ($M_{Z'}<10 T_{rh}$), with the highest efficiencies obtained for Z' bosons considerably heavier than the heavy neutrinos ($M_{Z'} > 100 M_1$). We show how the allowed region of the parameter space is modified in the presence of a Z' and we also obtain the minimum reheating temperature that is required for these models to be successful.