Generation of Neutrino mass from new physics at TeV scale and Multi-lepton Signatures at the LHC

TL;DR

This paper proposes a TeV-scale linear seesaw mechanism involving a scalar quadruplet and vector-like fermions to generate small neutrino masses, and explores multi-lepton signatures at the LHC as potential signals of new physics.

Contribution

It introduces a novel dimension-7 operator model with a scalar quadruplet and fermion triplets, and analyzes its distinctive multi-lepton collider signatures.

Findings

Same-sign tri-lepton signals from triply-charged scalars are promising for new physics detection.

Multi-lepton events with three to six leptons show negligible Standard Model background.

Lepton flavor violating four-lepton signals could serve as unique signatures for the model.

Abstract

In this paper we consider generation of naturally small neutrino masses from a dimension-7 operator. Such a term can arise in presence of a scalar quadruplet and a pair of vector-like fermion triplets and enables one to obtain small neutrino masses through TeV scale linear seesaw mechanism. We study the phenomenology of the charged scalars of this model, in particular, the multi-lepton signatures at the Large Hadron Collider. Of special importance are the presence of the same-sign-tri-lepton signatures originating from the triply-charged scalars. The Standard Model background for such processes is small and hence this is considered as smoking gun signal of new physics. We also looked for events with three, four, five and six-leptons which have negligible contamination from the Standard Model. We further point out the spectacular lepton flavour violating four-lepton signal which can be the hallmark for these type of models. We also compute the added contributions in the rate for the Standard Model Higgs decaying to two photons via the charged scalars in this model.