Abstract
A search for supersymmetry in events with large missing transverse momentum, jets, and at least one hadronically decaying $\tau$-lepton is presented. Two exclusive final states with either exactly one or at least two $\tau$-leptons are considered. The analysis is based on proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$ delivered by the Large Hadron Collider and recorded by the ATLAS detector in 2015 and 2016. No significant excess is observed over the Standard Model expectation. At 95% confidence level, model-independent upper limits on the cross section are set and exclusion limits are provided for two signal scenarios: a simplified model of gluino pair production with $\tau$-rich cascade decays, and a model with gauge-mediated supersymmetry breaking (GMSB). In the simplified model, gluino masses up to 2000 GeV are excluded for low values of the mass of the lightest supersymmetric particle (LSP), while LSP masses up to 1000 GeV are excluded for gluino masses around 1400 GeV. In the GMSB model, values of the supersymmetry-breaking scale are excluded below 110 TeV for all values of $\tan\beta$ in the range $2 \leq \tan\beta \leq 60$, and below 120 TeV for $\tan\beta>30$.
Highlights
Supersymmetry (SUSY) [1,2,3,4,5,6] introduces a symmetry between fermions and bosons, resulting in a SUSY partner for each Standard Model (SM) particle with identical quantum numbers except for a difference of half a unit of spin
A search for squarks and gluinos in events with jets, mhaodmroennitcuamllyisdpeecrafyoirnmgedτ-ulespintognps,pancodllimsiiosnsindgatatraant spveffisffirs1⁄4e 13 TeV recorded by the ATLAS detector at the Large Hadron Collider (LHC) in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb−1
Upper limits are set at 95% confidence level on the number of events that could be produced by processes beyond the Standard Model
Summary
Supersymmetry (SUSY) [1,2,3,4,5,6] introduces a symmetry between fermions and bosons, resulting in a SUSY partner (sparticle) for each Standard Model (SM) particle with identical quantum numbers except for a difference of half a unit of spin. Models with a small mass splitting between gluinos or squarks and the LSP, producing soft τ-leptons in the final state, are best covered by the 1τ channel. The analysis is performed using proton-pprffioffi ton (pp) collision data at a center-of-mass energy of s 1⁄4 13 TeV corresponding to an integrated luminosity of 36.1 fb−1, recorded with the ATLAS detector at the LHC in 2015 and 2016 For both SUSY models, the exclusion limits obtained significantly improve upon the previous ATLAS results. The free parameters of GMSB models are the SUSY-breaking mass scale in the messenger sector (Λ), the messenger mass scale (Mmes), the number of messenger multiplets (N5) of the 5 þ 5 ̄ representation of SU(5), the ratio of the two Higgs-doublet vacuum expectation values at the electroweak scale (tan β), the sign of the Higgsino mass term in the superpotential (signðμÞ 1⁄4 Æ1), and a gravitino-mass scale factor (Cgrav).
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