Search for squarks and gluinos in $pp$ collisions at $\sqrt{s} = 13$ TeV and $13.6$ TeV in events with $\tau$-leptons, jets and missing transverse momentum using the ATLAS detector

TL;DR

This paper reports a search for supersymmetric particles, specifically squarks and gluinos, in proton-proton collisions at 13 and 13.6 TeV, focusing on events with tau leptons, jets, and missing energy, setting new mass exclusion limits.

Contribution

The study introduces a combined analysis of three channels with tau leptons using both cut-and-count and machine learning methods, extending exclusion limits for gluino and squark masses.

Findings

Gluino masses below 2.25 TeV are excluded.

Squark masses up to 1.7 TeV are excluded.

Analysis techniques improve sensitivity to supersymmetry signals.

Abstract

A search for R-parity-conserving supersymmetry in events with large missing transverse momentum, jets and at least one hadronically decaying $\tau$-lepton is presented. Both gluino and squark pair production are considered, with the cascade decay of each gluino or squark producing either a $\tau$-slepton or a $\tau$-sneutrino. Three channels are examined, requiring either exactly one hadronically decaying $\tau$-lepton and no other leptons, exactly one hadronically decaying $\tau$-lepton and at least one other lepton, or two or more hadronically decaying $\tau$-leptons. Analyses in the three channels are optimised independently and combined statistically. Two separate analysis strategies, either a cut-and-count or machine-learning approach, are used. The search uses 140 $\mathrm{fb}^{-1}$ and 51.8 $\mathrm{fb}^{-1}$ of $pp$ collision data recorded by the ATLAS detector at the Large Hadron Collider during 2015-2018 at $\sqrt{s} = 13$ TeV and 2022-2023 at $\sqrt{s} = 13.6$ TeV, respectively. Gluino masses below $2.25$ TeV and squark masses up to $1.7$ TeV are excluded.