Discovering $E_6$ SUSY models in gluino cascade decays at the LHC

TL;DR

This paper explores how $E_6$ inspired supersymmetric models produce distinctive gluino decay signatures at the LHC, differing from the MSSM, and demonstrates their detectability through detailed Monte Carlo analyses.

Contribution

It introduces a new $E_6$ SUSY model framework, analyzes its collider signatures, and provides publicly available tools for distinguishing it from the MSSM at the LHC.

Findings

$E_6$ models produce longer decay chains with more leptons and jets.

$E_6$ gluinos can mimic lighter MSSM gluinos in certain channels.

Enhanced multi-lepton signatures improve model distinguishability.

Abstract

We point out that the extra neutralinos and charginos generically appearing in a large class of $E_6$ inspired models lead to distinctive signatures from gluino cascade decays in comparison to those from the Minimal Supersymmetric Standard Model (MSSM). These signatures involve longer decay chains, more visible transverse energy, higher multiplicities of jets and leptons, and less missing transverse energy than in the MSSM. These features make the gluino harder to discover for certain types of conventional analyses, for example in the 6 jet channel we show that a 1 TeV MSSM gluino may resemble an 800 GeV $E_6$ gluino. However, the enriched lepton multiplicity provides enhanced 3- and 4-lepton signatures, which are much more suppressed in the case of the MSSM. As an example we analyse various scenarios in the E$_6$SSM, demonstrating the utility of a \texttt{CalcHEP} model that we have now made publicly available on HEPMDB (High Energy Physics Models DataBase). After extensive scans over the parameter space, we focus on representative benchmark points. We perform detailed Monte Carlo analyses, concentrating on the 3-lepton channel at the 7, 8, and 14 TeV Large Hadron Collider (LHC), and demonstrate that $E_6$ inspired models are clearly distinguishable from the MSSM in gluino cascade decays. We emphasise to the LHC experimental groups that the distinctive features present in gluino cascade decays, such as those discussed here, not only represents a unique footprint of a particular model but also may provide the key to an earlier discovery of supersymmetry.