Consistency of the recent ATLAS $Z+E_T^{\rm miss}$ excess in a simplified GGM model

TL;DR

This paper evaluates whether a simplified GGM model can explain the ATLAS Z+E_T^{miss} excess and finds that, after considering various constraints, the model cannot account for the observed excess.

Contribution

The study tests the consistency of a simplified GGM model with LHC data and demonstrates its inability to explain the ATLAS excess.

Findings

The GGM model cannot explain the ATLAS excess after constraints.

Non-decoupling effects split the parameter space into two regions.

Additional leptons are expected in one region, zero-lepton events in the other.

Abstract

ATLAS recently reported a $3\sigma$ excess in a leptonic-$Z+E_T^{\rm miss}$ channel. This was interpreted in the literature in a simplified General Gauge Mediation model containing a gluino, a higgsino next-to-lightest supersymmetric particle (NLSP) and a gravitino lightest supersymmetric particle (LSP). We test the consistency of this explanation in lieu of the results of the corresponding search in CMS, and other LHC searches for New Physics. Due to non-decoupling effects from squarks the parameter space of these models is split into two regions; in one region additional leptons via top quark production is expected, while the other region sees a large probability for zero-lepton events. After combining the relevant constraints we find that these models cannot explain the ATLAS excess.