Multilepton and multiphoton signatures of supersymmetry at the LHC

TL;DR

This paper explores potential explanations for multilepton and multiphoton signals at the LHC, proposing new models and search strategies to detect non-minimal supersymmetry scenarios involving multiple hidden sectors and pseudo-goldstini.

Contribution

It introduces a simplified gauge mediation model to explain multilepton excesses and proposes novel search strategies for multiphoton signatures from non-minimal SUSY models with multiple hidden sectors.

Findings

A possible explanation for CMS multilepton excess using gauge mediation.

Identification of the limitations of current LHC searches for these signatures.

Proposal of new search strategies to detect multiphoton plus missing energy signals.

Abstract

Motivated by the absence of any clear signal of physics beyond the Standard Model at the LHC after Run I, we discuss one possible slight hint of new physics and one non-minimal extension of the Standard Model. In the first part we provide a tentative explanation of a small excess of multilepton events, observed by the CMS collaboration, by means of a simplified model of gauge mediated supersymmetry breaking. In the second part we discuss how the standard phenomenology of gauge mediation can be significantly modified if one makes the non-minimal assumption that supersymmetry is broken in more than one hidden sector. Such multiple hidden sector models involve light neutral fermions called pseudo-goldstini and, due to the extra decay steps they induce, where soft photons are emitted, these models give rise to multiphoton plus missing energy signatures. We discuss why the existing LHC searches are poorly sensitive to these model and we propose new searches designed to probe them.