Search for top squarks decaying to tau sleptons in $pp$ collisions at $\sqrt{s}= 13$ TeV with the ATLAS detector

TL;DR

This paper reports a search for top squarks decaying to tau sleptons in proton-proton collisions at 13 TeV, using ATLAS data, finding no deviation from the Standard Model and setting mass exclusion limits up to 1.16 TeV for top squarks.

Contribution

First search for top squarks decaying to tau sleptons in final states with tau leptons, b-jets, and missing energy at 13 TeV with ATLAS, setting new mass exclusion limits.

Findings

No significant excess observed over Standard Model predictions.

Excluded top squark masses up to 1.16 TeV at 95% CL.

Excluded tau slepton masses up to 1.00 TeV at 95% CL.

Abstract

A search for direct pair production of top squarks in final states with two tau leptons, $b$-jets, and missing transverse momentum is presented. The analysis is based on proton-proton collision data at $\sqrt{s} = 13$ TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$ recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. Two exclusive channels with either two hadronically decaying tau leptons or one hadronically and one leptonically decaying tau lepton are considered. No significant deviation from the Standard Model predictions is observed in the data. The analysis results are interpreted in terms of model-independent limits and used to derive exclusion limits on the masses of the top squark $\tilde t_1$ and the tau slepton $\tilde \tau_1$ in a simplified model of supersymmetry with a nearly massless gravitino. In this model, masses up to $m(\tilde t_1) = 1.16$ TeV and $m(\tilde \tau_1) = 1.00$ TeV are excluded at 95% confidence level.