  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.
