Multilepton and multiphoton signatures of supersymmetry at the LHC

Paper i proceeding, 2014

Motivated by the absence of any clear signal of physics beyond the Standard Model (SM) at the LHC after Run I, we discuss one possible slight hint of new physics and one nonminimal extension of the SM. 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 (GMSB). In the second part we discuss how the standard phenomenology of GMSB 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.