ATLAS Z + missing transverse energy excess in the MSSM.

We demonstrate that the 3a excess observed by ATLAS in the Z + MET channel can be explained within the context of the MSSM. Using the freedom inherent in the pMSSM, we perform a detailed analysis of the parameter space and find a scenario that describes the excess while simultaneously complying with all other search constraints from the Run I data at 7 and 8 TeV, including the Z + MET analysis by CMS. We generate a small sample of simplified models, using promising models from our existing pMSSM sample as seeds, and study their properties. The successful region is described by the production of lst/2nd generation squark pairs, followed by their decay into a bino-like neutralino which in tum decays into a Higgsino-like LSP triplet by emitting a Z boson, i.e., q → B → h with q = QL, μR, or dR. The sweet spot for the sparticle spectrum is found to have squark masses in the 500-750 GeV range, with bino masses near 350 GeV with a mass splitting of 150-200 GeV with the Higgsino LSP. If this excess holds, then this scenario predicts that a signal will be observed in the 0l + jets and/or ll+jets searches in the early operations of Run II. [ABSTRACT FROM AUTHOR]