Lepton Number Violation: from $0\nu\beta\beta$ Decay to Long-Lived Particle Searches

TL;DR

This paper explores how different experimental approaches, including neutrinoless double beta decay and long-lived particle searches at colliders, complement each other in detecting lepton number violation within a specific theoretical model.

Contribution

It demonstrates the complementary sensitivities of $0 uetaeta$ decay and collider LLP searches in probing lepton number violation in a simplified scalar-fermion model.

Findings

$0 uetaeta$ decay experiments cover larger parameter space regions.

LLP searches uniquely probe smaller couplings and masses.

Existing collider constraints are also analyzed for their impact.

Abstract

We study the complementary tests of lepton number violation in $0\nu\beta\beta$-decay experiments, long-lived particle (LLP) searches at the LHC main detectors ATLAS/CMS, and a proposed far detector MATHUSLA. In the context of a simplified model with a scalar doublet $S$ and a Majorana fermion $F$, we show that while the $0\nu\beta\beta$-decay experiments can probe a larger portion of parameter space, the LLP searches can uniquely probe the region of smaller couplings and masses if $S$ is at TeV scale while $F$ is at or below the electroweak scale. We also investigate constraints on the parameter space from the existing searches that are insensitive to lepton number violation.