
Measuring a nonzero value for the cross section of any lepton number violating (LNV) process would put a strong lower limit on the washout factor for the effective lepton number density in the early Universe at times close to the electroweak phase transition and thus would lead to important constraints on any highscale model for the generation of the observed baryon asymmetry based on LNV. In particular, for leptogenesis (LG) models with masses of the righthanded neutrinos heavier than the mass scale observed at the LHC, the implied large washout factors would lead to a violation of the outofequilibrium condition and exponentially suppress the net lepton number produced in such LG models. We thus demonstrate that the observation of LNV processes at the LHC results in the falsification of highscale LG models. However, no conclusions about the viability of LG models can be drawn from the nonobservation of LNV processes.
