Trilepton signals: the golden channel for seesaw searches at LHC

TL;DR

This paper demonstrates that trilepton signals are highly effective for detecting various seesaw mediators at the LHC, with discovery potential depending on the type of neutrino mass model and additional gauge interactions.

Contribution

It provides a comparative analysis of trilepton signals for different seesaw models and explores the impact of new gauge interactions on heavy neutrino observability at the LHC.

Findings

Scalar and fermion triplets detectable up to 500-700 GeV

Fermion singlets marginally observable without new physics

Heavy neutrinos observable up to 2 TeV with new gauge interactions

Abstract

The comparison of samples with different number of charged leptons shows that trilepton signals are the most significant ones for seesaw mediators. As previously pointed out, this is indeed the case for scalar (type II) and fermion (type III) triplets at LHC, which can be discovered in this channel for masses up to 500-700 GeV and an integrated luminosity of 30 fb^-1; whereas fermion singlets (type I) are marginally observable if there are no further new physics near the TeV scale. However, if there are new gauge interactions at this scale coupling to right-handed neutrinos, as in left-right models, heavy neutrinos are observable up to masses ~ 2 TeV for new gauge boson masses up to ~ 4 TeV, as we discuss in some detail.