Search for direct stau production in events with two hadronic $\tau$-leptons in $\sqrt{s} = 13$ TeV $pp$ collisions with the ATLAS detector

TL;DR

This paper reports a search for supersymmetric stau particles in proton-proton collisions at 13 TeV, finding no evidence of their production and setting exclusion limits on their mass range.

Contribution

It presents the first ATLAS search for direct stau production in final states with two hadronic tau leptons, establishing new mass exclusion limits.

Findings

No significant excess over Standard Model background.

Excluded stau masses from 120 GeV to 390 GeV at 95% CL.

Set constraints on supersymmetric models with degenerate stau states.

Abstract

A search for the direct production of the supersymmetric partners of $\tau$-leptons (staus) in final states with two hadronically decaying $\tau$-leptons is presented. The analysis uses a dataset of $pp$ collisions corresponding to an integrated luminosity of $139$ fb$^{-1}$, recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of direct production of stau pairs with each stau decaying into the stable lightest neutralino and one $\tau$-lepton in simplified models where the two stau mass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidence level for a massless lightest neutralino.