Searches for direct slepton production in the compressed-mass corridor in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

Abstract

This paper presents searches for the direct pair production of charged light-flavour sleptons, each decaying into a stable neutralino and an associated Standard Model lepton. The analyses focus on the challenging ``corridor'' region, where the mass difference, $\Delta m$, between the slepton ($\tilde{e}$ or $\tilde{\mu }$) and the lightest neutralino (${\tilde{\chi }}_1^0$) is less or similar to the mass of the $W$ boson, $m(W)$, with the aim to close a persistent gap in sensitivity to models with $\Delta m\lesssim m(W)$. Events are required to contain a high-energy jet, significant missing transverse momentum, and two same-flavour opposite-sign leptons ($e$ or $\mu$). The analysis uses $pp$ collision data at $\sqrt{s}=13$ TeV recorded by the ATLAS detector, corresponding to an integrated luminosity of 140 fb${}^{-1}$. Several kinematic selections are applied, including a set of boosted decision trees. These are each optimised for different $\Delta m$ to provide expected sensitivity for the first time across the full $\Delta m$ corridor. The results are generally consistent with the Standard Model, with the most significant deviations observed with a local significance of 2.0 $\sigma$ in the selectron search, and 2.4 $\sigma$ in the smuon search. While these deviations weaken the observed exclusion reach in some parts of the signal parameter space, the previously present sensitivity gap to this corridor is largely reduced. Constraints at the 95% confidence level are set on simplified models of selectron and smuon pair production, where selectrons (smuons) with masses up to 300 (350) GeV can be excluded for $\Delta m$ between 2 GeV and 100 GeV.

66 pages in total, author list starting page 49, 14 figures, 11 tables, published in JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HMBS-2024-64/

References in corpus (17)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Herwig++ Physics and Manual
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• Single-top Wt-channel production matched with parton showers using the POWHEG method
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• Single-top hadroproduction in association with a W boson
• Electroweak and QCD corrections to Higgs production via vector-boson fusion at the LHC
• Strong and electroweak corrections to the production of Higgs+2jets via weak interactions at the LHC
• HistFitter software framework for statistical data analysis
• Higgs boson production in association with top quarks in the POWHEG BOX
• vh@nnlo - Higgs Strahlung at hadron colliders
• Soft gluon resummation for gluon-induced Higgs Strahlung
• Monojet plus soft dilepton signal from light higgsino pair production at LHC14
• Threshold Resummation for Slepton-Pair Production at Hadron Colliders
• A boost for the EW SUSY hunt: monojet-like search for compressed sleptons at LHC14 with 100 fb^-1

Cited by in corpus (2)

• General search for supersymmetric particles in scenarios with compressed mass spectra using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Learning Selection Cuts With Gradients