Exotic lepton searches via bound state production at the LHC

Neil D Barrie,Archil Kobakhidze,Shelley Liang,Matthew Talia,Lei Wu

doi:10.1016/j.physletb.2018.03.087

Abstract

Heavy long-lived multi-charged leptons (MCLs) are predicted by various new physics models. These hypothetical MCLs can form bound states, due to their high electric charges and long life times. In this work, we propose a novel strategy of searching for MCLs through their bound state productions and decays. By utilising LHC-8 TeV data in searching for resonances in the diphoton channel, we exclude the masses of isospin singlet heavy leptons with electric charge |q|≥6 (in units of electron charge) lower than ∼1.2 TeV, which are much stronger than the corresponding 8 TeV LHC bounds from analysing the high ionisation and the long time-of-flight of MCLs. By utilising the current 13 TeV LHC diphoton channel measurements the bound can further exclude MCL masses up to ∼1.6 TeV for |q|≥6. Also, we demonstrate that the conventional LHC limits from searching for MCLs produced via Drell–Yan processes can be enhanced by including the contribution of photon fusion processes.

Highlights

Heavy long-lived multi-charged leptons (MCLs) are predicted by various extensions of the Standard Model (SM)
The ATLAS and CMS collaborations have extensively searched for long-lived MCLs by analysing the anomalously high ionisation and the long TOF to the outer muon system at the LHC [5, 6, 7]
We can see that 8 TeV LHC data searching for resonances in the diphoton channel can exclude the mass of a heavy lepton with hypercharge YL = 6 and 7 up to 1.2 and 1.5 TeV respectively, which is much stronger than the corresponding ATLAS and CMS bound from analysing the high ionisation and the long time-of-flight in DY production

Summary

Introduction

Heavy long-lived multi-charged leptons (MCLs) are predicted by various extensions of the Standard Model (SM) (for a review, see [1]). The ATLAS and CMS collaborations have extensively searched for long-lived MCLs by analysing the anomalously high ionisation and the long TOF to the outer muon system at the LHC [5, 6, 7]. Such low efficiencies mean that a different approach is required Due to their high charges and long life times, the MCLs are expected to form bound states via the electromagnetic interaction, which will subsequently decay to SM particles. Our proposal can be applied to other representations of MCLs with modifications in the production and decay calculations

Constraints on MCLs

MCL Bound State Production at the LHC

Findings

Conclusion