Impact of Lepton Number Violation at the LHC on Models of Leptogenesis

TL;DR

Detecting lepton number violation at the LHC could significantly constrain high-scale leptogenesis models by indicating strong washout effects that diminish the early Universe lepton asymmetry, impacting theories of baryogenesis.

Contribution

This paper analyzes how LHC observations of lepton number violation can impose constraints on high-scale leptogenesis models, highlighting the importance of LNV searches for understanding baryogenesis.

Findings

LHC signals of LNV imply large washout factors for lepton asymmetry.

Such signals can exclude certain high-scale leptogenesis scenarios.

LNV searches are powerful probes for the origin of matter-antimatter asymmetry.

Abstract

The discovery of lepton number violation (LNV) at the LHC would have profound consequences for the viability of high-scale leptogenesis models. As an example, we discuss the case of observing a signal with two same-sign leptons, two jets and no missing energy. This would imply a large washout factor for the lepton number density in the early Universe, which leads to a significant constraint on any high-scale model for the generation of the observed baryon asymmetry. In a standard leptogenesis scenario, the corresponding washout factor would strongly decrease a pre-existing lepton asymmetry and thus would render leptogenesis models that generate a (B-L) asymmetry far above the LHC scale ineffective. Therefore, LHC searches focused on LNV processes without missing energy are powerful probes for high-scale leptogenesis models and correspondingly shed light on the nature of baryogenesis and neutrino masses.