Conciliating SUSY with the Z-peaked excess

TL;DR

This paper investigates whether supersymmetry models can explain a Z boson excess observed at the LHC, proposing a specific light gluino and heavy neutralino scenario consistent with the data and discussing implications for future searches.

Contribution

It introduces a SUSY model with light gluinos and a heavy neutralino NLSP that can account for the Z-peaked excess, aligning with experimental constraints.

Findings

Light gluinos and heavy neutralino NLSP can reproduce the excess.

A general gauge mediation model matching the observed signal is constructed.

Implications for Run II and gluino searches are discussed.

Abstract

The ATLAS experiment observed an excess at the $3\sigma$ level in the channel of $Z$ boson, jets and high missing transverse momentum in the full 2012 dataset at 8 TeV while searching for SUSY. The question arises whether the abundance and the kinematical features of this excess are compatible with the yet unconstrained supersymmetric realm, respecting at the same time the measured Higgs boson properties and dark matter density. By trying to explain this signal with SUSY we find that only relatively light gluinos together with a heavy neutralino NLSP decaying predominantly to a $Z$ boson plus a light gravitino could reproduce the excess. We construct an explicit general gauge mediation model able to match the observed signal. More sophisticated models could also reproduce the signal, as long as it features light gluinos, or heavy particles with a strong production cross section, producing at least one $Z$ boson in its decay chain. The implications of our findings for the Run II at LHC with the scaling on the $Z$ peak, as well as for the direct search of gluinos and other SUSY particles, are also discussed.