A joint explanation for the soft lepton and monojet LHC excesses in the wino-bino model

TL;DR

This study addresses potential LHC excesses in jets+MET and soft-lepton+MET channels by performing public recasts of CMS and ATLAS analyses for compressed electroweakino spectra within a wino-bino(+) MSSM limit. It combines a CMS soft-lepton recast implemented in HackAnalysis with an ATLAS multijet recast in MadAnalysis 5 to perform a joint interpretation, identifying a parameter region around $m_{ ilde{ ext{χ}}_2^0}\approx320$ GeV and $m_{ ilde{ ext{χ}}_1^0}\approx20$ GeV that better describes the data than the SM and is compatible with $\,\Omega h^2\approx0.12$ under standard freeze-out. The work provides detailed recasting materials, including covariance matrices and cutflows, and demonstrates consistency with CMS expectations while highlighting limitations in statistical modeling for excess-dominated regions. It also tests the multijet channel’s reach for compressed electroweakino scenarios and discusses how simplified wino-bino spectra map onto full MSSM frameworks, offering public tools for broader cross-experiment checks and future refinements.

Abstract

We present new recasts of the CMS Run 2 soft-leptons + missing energy analysis and the ATLAS Run 2 multijet + missing energy analysis. These analyses are relevant for probing the parameter space of electroweak-charged particles with compressed spectra. We review these analyses and detail their implementation and validation in HackAnalysis (for CMS) and MadAnalysis 5 (ATLAS). We then use these new recasts to combine four LHC analyses to identify a region of parameter space of the "wino-bino" simplified model, which corresponds to a limit of the Minimal Supersymmetric Standard Model in which higgsinos are decoupled, that is preferred over the Standard Model by excesses in the data. We find that the favoured region is compatible with the observed dark matter relic density, assuming freeze out within a standard cosmology, and we comment on the importance of this result and on how the simplified model should be mapped onto a complete supersymmetric model.

Figures (2)

• Figure 1: Validation of the implementation of CMS-SUS-18-004 in HackAnalysis by comparing limits on the wino-bino parameter space. Top: "Full" simplified likelihood. Bottom: Alternative simplified likelihood, by combining two pairs of bins. See text for details.
• Figure 2: 95% confidence level exclusion contours in the $(m_{\tilde{g}}, m_{\tilde{\chi}_1^0})$ mass plane. We compare the observed (red) and expected (blue) limits provided by ATLAS to predictions obtained with our implementation of ATLAS-SUSY-2018-22 in MadAnalysis 5 for gluino pair production followed by the decay $\tilde{g} \rightarrow q \bar{q} \tilde{\chi}^0_1$. Red cross markers represent excluded points while green dot markers correspond to allowed points.