Leptogenesis and neutral gauge bosons

TL;DR

This paper explores low-scale leptogenesis involving right-handed neutrinos and a light $Z'$ gauge boson, highlighting how upcoming experiments could test or falsify the model by detecting specific signatures.

Contribution

It demonstrates that leptogenesis can be tested and potentially falsified through combined collider and fixed-target experiments observing $Z'$ and $N$ particles.

Findings

Leptogenesis viability depends on $Z'$ coupling and mass constraints.

Future experiments can detect $Z'$ and $N$ signatures.

Double observation of $Z'$ and $N$ can falsify leptogenesis models.

Abstract

We consider low-scale leptogenesis via right-handed neutrinos $N$ coupled to a $Z'$ boson, with gauged $U(1)_{B-L}$ as a simple realization. Keeping the neutrinos sufficiently out of equilibrium puts strong bounds on the $Z'$ coupling strength and mass, our focus being on light $Z'$ and $N$, testable in the near future by SHiP, HPS, Belle II, and at the LHC. We show that leptogenesis could be robustly falsified in a large region of parameter space by the double observation of $Z'$ and $N$, e.g. in the channel $pp\to Z' \to NN$ with displaced $N$-decay vertex, and by several experiments searching for light $Z'$, according to the mass of $N$.