On the coverage of electroweak-inos within the pMSSM with SModelS -- a comparison with the ATLAS pMSSM study

TL;DR

This paper benchmarks SModelS v3.0 against the ATLAS Run 2 pMSSM study focused on electroweak-inos, and extends the analysis by adding CMS results and exploring the impact of combining multiple analyses. It finds generally good agreement with ATLAS in the electroweakino sector, while CMS gluino constraints and analysis combinations substantially increase coverage, particularly for non-bino-like LSPs and compressed spectra. The work highlights regions with light EWKinos that survive current limits and demonstrates the value and limitations of a full database approach, emphasizing the need for comprehensive efficiency maps, Higgs-mediated topologies, and long-lived particle signatures. Overall, the results underscore the importance of a multifaceted, global likelihood approach to close loopholes in the expansive pMSSM parameter space and guide futureRun 3 analyses.

Abstract

The ATLAS collaboration has recently performed a vast scan of the phenomenological Minimal Supersymmetric Standard Model (pMSSM) with a focus on the electroweak-ino sector, and analysed how their Run 2 searches for electroweak production of supersymmetric (SUSY) particles constrain this dataset. All the SLHA files from the scan as well as the constraints from the eight individual searches considered by ATLAS were made publicly available. We use this material to study how well the ATLAS constraints can be reproduced with SModelS v3.0. Moreover, we explore how the picture changes when also including CMS results, and what can be gained by the statistical combination of analyses. Finally, we discuss the part of parameter space with light electroweak-inos that remains valid despite the stringent LHC limits. Our results underscore the need of a broad, multifaceted approach for maximising sensitivity and closing loopholes in the extensive SUSY parameter space.

Figures (13)

• Figure 1: Exclusion by the most sensitive analysis in SModelS, considering only ATLAS EWKino results in the database (cyan) or considering all ATLAS+CMS EWKino results (black). The open red histogram shows the corresponding exclusion from ATLAS:2024qmx. The full dataset is represented in grey.
• Figure 2: Fraction of points excluded by the ATLAS pMSSM study (left) and by ATLAS EWKino results in SModelS (right). The most sensitive analysis is selected for each point. No points populate the black bins.
• Figure 3: Relative difference between the SModelS and ATLAS exclusions, ($\#$excl(SModelS)$-\#$excl(ATLAS))/$\#$excl(ATLAS), for the whole scan (left) and for the non-bino LSP points (right). The most sensitive analysis is selected for each point. For SModelS, only ATLAS EWKino results are considered. No points populate the dark grey bins.
• Figure 4: Scatter plot of non-bino LSP points showing BR($\tilde{\chi}^\pm_2 \to \tilde{\chi}^\pm_1+h$) versus the $\Tilde{\chi}_{1}^{\pm}$ higgsino content (U$_{12}^2$+V$_{12}^2$)/2. The colour code indicates the branching ratio for $\tilde{\chi}^0_3 \to \tilde{\chi}^0_1+h$ decays. The points excluded by ATLAS-SUSY-2018-05 in ATLAS:2024qmx but not excluded by the most sensitive analysis in SModelS are overlaid in black.
• Figure 5: Points (in colour) excluded by ATLAS in ATLAS:2024qmx, but not excluded by the most sensitive ATLAS analysis in SModelS, on the left for the full EWKino dataset, on the right for the subset of non-bino-like LSP points. The most sensitive analysis in ATLAS:2024qmx is indicated in colour; grey points represent all other scan points, excluded and non-excluded ones.