Collider Signatures for Heavy Lepton Triplet in Type I+III Seesaw

TL;DR

This paper investigates collider signatures of heavy lepton triplets predicted by a minimal SU(5) model with hybrid Type I and III seesaw mechanisms, proposing detection strategies at hadron and lepton colliders.

Contribution

It introduces a distinctive collider signature for heavy lepton triplets and assesses their detectability at current and future colliders, providing a method to test the hybrid seesaw model.

Findings

Heavy leptons detectable up to 200 GeV at Tevatron

Search reach extends to 450-700 GeV at LHC 14 TeV

Distinctive lepton number violating signature identified

Abstract

The minimal SU(5) theory augmented by the fermionic adjoint representation restores the coupling constant unification and gives realistic neutrino masses and mixing through the hybrid Type I and Type III seesaw. The crucial prediction of the theory is an SU(2) lepton triplet with the mass below TeV. We study the signature of these heavy leptons and propose the strategy to test this mechanism at the hadron and lepton colliders. The smoking gun evidence of the theory is Delta L=2 lepton number violation through events of a pair of like-sign leptons plus four jets without significant missing energy at hadron colliders. We find that via this unique channel, the heavy lepton can be searched for up to a mass of 200 GeV at the Tevatron with 8 fb^-1, and up to 450 (700) GeV at the LHC of 14 TeV C.M.energy with 10 (100) fb^-1. The signal rate at the 10 TeV LHC is reduced to 60-35% for a mass of 200-700 GeV. We also comment on how to distinguish this theory from other models with similar heavy leptons. Finally, we compare the production rates and angular distributions of heavy leptons in e+e- collisions for various models.