Z-peaked excess in goldstini scenarios

Abstract

We study a possible explanation of a 3.0 $\sigma$ excess recently reported by the ATLAS Collaboration in events with Z-peaked same-flavour opposite-sign lepton pair, jets and large missing transverse momentum in the context of gauge-mediated SUSY breaking with more than one hidden sector, the so-called goldstini scenario. In a certain parameter space, the gluino two-body decay chain $\tilde{g}\to g{\tilde{\chi }}_{1,2}^0\to gZ{\tilde{G}}^{\prime }$ becomes dominant, where ${\tilde{\chi }}_{1,2}^0$ and ${\tilde{G}}^{\prime }$ are the Higgsino-like neutralino and the massive pseudo-goldstino, respectively, and gluino pair production can contribute to the signal. We find that a mass spectrum such as $m_{\tilde{g}}\sim 1000$ GeV, $m_{{\tilde{\chi }}_{1,2}^0}\sim 800$ GeV and $m_{{\tilde{G}}^{\prime }}\sim 600$ GeV demonstrates the rate and the distributions of the excess, without conflicting with the stringent constraints from jets plus missing energy analyses and with the CMS constraint on the identical final state.

9 pages, 7 figures, 1 table; v2: the CMS binned on-Z analyses added, resulting in a small change in the best fit benchmark; v3: some issues clarified, fig.7 added, version to appear in PLB

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• Mixed Stops and the ATLAS on-Z Excess
• ATLAS on-Z Excess via gluino-Higgsino-singlino decay chains in the NMSSM
• Testing ATLAS Z+MET Excess with LHC Run 2
• Aspects of astrophysical particle production and beyond the Standard Model phenomenology