Discriminating between lepton number violating scalars using events with four and three charged leptons at the LHC

TL;DR

This paper proposes a method to distinguish between different types of lepton number violating scalars at the LHC by analyzing events with four or three charged leptons, helping identify their weak isospin properties.

Contribution

It introduces a novel analysis technique using multi-lepton events to determine the weak isospin multiplet of doubly-charged scalars, including isosinglet and isodoublet discrimination.

Findings

Event analysis can identify the scalar's weak isospin multiplet.

Discrimination between isosinglet and isodoublet is possible under certain conditions.

Method enhances understanding of lepton number violation signals at the LHC.

Abstract

Many Standard Model extensions predict doubly-charged scalars; in particular, all models with resonances in charged lepton-pair channels with non-vanishing lepton number; if these are pair produced at the LHC, the observation of their decay into $l^\pm l^\pm W^\mp W^\mp$ will be necessary in order to establish their lepton-number violating character, which is generally not straightforward. Nonetheless, the analysis of events containing four charged leptons (including scalar decays into one or two taus as well as into W bosons) makes it possible to determine whether the doubly-charged excitation belongs to a multiplet with weak isospin T = 0, 1/2, 1, 3/2 or 2 (assuming there are no excitations with charge > 2); though discriminating between the isosinglet and isodoublet cases is possible only if charged-current events cannot produce the doubly-charged isosinglet.