Probing Lepton Number Violation at Same-Sign Lepton Colliders

TL;DR

This paper explores how same-sign muon colliders can detect or constrain lepton number violation through processes involving Majorana neutrinos and neutrinophilic scalars, offering a promising avenue for new physics discovery.

Contribution

It demonstrates the potential of proposed same-sign muon colliders to probe lepton number violation with modest energy and luminosity, focusing on Majorana neutrinos and neutrinophilic scalars.

Findings

Colliders can reveal direct evidence of lepton number violation.

They can significantly constrain unexplored parameter space.

Potential to discover neutrinophilic scalars.

Abstract

Same-sign lepton colliders offer a promising environment to probe lepton number violation. We study processes that change lepton number by two units in the context of Majorana heavy neutral leptons and neutrinophilic scalars at $\mu$TRISTAN, a proposed same-sign muon collider. Our work shows that such colliders, with modest energy and luminosity requirements, can either reveal direct evidence of lepton number violation or significantly constrain unexplored regions of parameter space, especially in the case of a neutrinophilic scalar.