Search for long-lived charginos and $\tau$-sleptons using final states with a disappearing track in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

Abstract

This paper reports a search for decays of long-lived charginos or $\tau$-sleptons to final states containing a short disappearing track, a single high-energy jet, and missing transverse momentum. The search uses 137 fb${}^{-1}$ of data from 13 TeV proton-proton collisions recorded by the ATLAS detector during Run 2 of the LHC. Multiple search regions are defined, all requiring the presence of a track reconstructed from either three or four measurements in the innermost layers of the ATLAS detector. Regions with tracks having only three measurements are further characterised by the absence or presence of a low-energy charged pion reconstructed using a dedicated algorithm, leveraging machine learning. Data-driven methods are used to estimate the background contributions in the search regions. No significant excesses are found and 95% CL lower limits are placed on the masses of charginos and $\tau$-sleptons in the lifetime range $0.01-10$ ns. Observed (expected) mass limits of up to 225 GeV (250 GeV) are set for pure-higgsino charginos in scenarios with lifetimes below 0.03 ns, where the electroweakino mass splitting is entirely due to loop corrections involving the Standard Model bosons, and up to 720 GeV (840 GeV) for charginos with a lifetime of around 1 ns. For wino production, charginos with masses up to 880 GeV (1020 GeV) are excluded for lifetimes of around 1 ns. For $\tau$-sleptons with lifetimes of around 1 ns, masses are excluded up to 320 GeV (390 GeV) in Constrained Minimal Supersymmetric Standard Model scenarios and 300 GeV (380 GeV) in Gauge-Mediated Supersymmetry-Breaking scenarios.

55 pages in total, author list starting page 38, 14 figures, 6 tables, published in JHEP. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HMBS-2024-66

References in corpus (51)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• An Introduction to PYTHIA 8.2
• A Brief Introduction to PYTHIA 8.1
• FastJet user manual
• Asymptotic formulae for likelihood-based tests of new physics
• Parton distributions for the LHC Run II
• Parton distributions with LHC data
• Out Of This World Supersymmetry Breaking
• Scattering Amplitudes with Open Loops
• Gaugino Mass without Singlets
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• QCD Matrix Elements + Parton Showers
• Minimal Dark Matter
• Comix, a new matrix element generator
• Event Generation with Sherpa 2.2
• QCD matrix elements + parton showers: The NLO case
• High-precision QCD at hadron colliders: electroweak gauge boson rapidity distributions at NNLO
• QCD matrix elements and truncated showers
• Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations
• Study of Constrained Minimal Supersymmetry
• A critical appraisal of NLO+PS matching methods
• OpenLoops 2
• Natural SUSY Endures
• The Production of Charginos/Neutralinos and Sleptons at Hadron Colliders
• Simplified Models for a First Characterization of New Physics at the LHC
• Squark and gluino production cross sections in pp collisions at $\sqrt{s}$ = 13, 14, 33 and 100 TeV
• Neutralino-Stau Coannihilation and the Cosmological Upper Limit on the Mass of the Lightest Supersymmetric Particle
• HistFitter software framework for statistical data analysis
• One-Loop Analysis of the Electroweak Breaking in Supersymmetric Models and the Fine-Tuning Problems
• Precision predictions for electroweak superpartner production at hadron colliders with Resummino
• Merging Multi-leg NLO Matrix Elements with Parton Showers
• Gaugino production in proton-proton collisions at a center-of-mass energy of 8 TeV
• Evaluation of three methods for calculating statistical significance when incorporating a systematic uncertainty into a test of the background-only hypothesis for a Poisson process
• Mass Splitting between Charged and Neutral Winos at Two-Loop Level
• Massive Doublet Leptons
• Searching for Directly Decaying Gluinos at the Tevatron
• Higgsino Dark Matter in High-Scale Supersymmetry
• WMAP constraints on SUGRA models with non-universal gaugino masses and prospects for direct detection
• Threshold resummation for gaugino pair production at hadron colliders
• Revisiting slepton pair production at the Large Hadron Collider
• Threshold Resummation for Slepton-Pair Production at Hadron Colliders
• Higgsino Dark Matter or Not: Role of Disappearing Track Searches at the LHC and Future Colliders
• Hunting wino and higgsino dark matter at the muon collider with disappearing tracks
• Long life stau in the minimal supersymmetric standard model
• Natural Dark Matter in SUSY GUTs with Non-universal Gaugino Masses
• Slepton pair production at the LHC in NLO+NLL with resummation-improved parton densities
• Revisiting light neutralino scenarios in the MSSM
• Measuring Lepton Flavour Violation at LHC with Long-Lived Slepton in the Coannihilation Region
• Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV $pp$ collider
• Electroweak superpartner production at 13.6 TeV with Resummino