Search for pair production of gluinos decaying via stop and sbottom in events with $b$-jets and large missing transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

TL;DR

This paper reports a search for gluino pair production decaying via third-generation squarks in proton-proton collisions at 13 TeV, setting new exclusion limits on gluino masses with no observed excess over background.

Contribution

First search at 13 TeV for gluinos decaying via stop and sbottom with detailed event selection, extending previous exclusion limits significantly.

Findings

No excess observed above background predictions.

Excluded gluino masses below 1.78 TeV for sbottom decay mode.

Excluded gluino masses below 1.76 TeV for stop decay mode.

Abstract

A search for Supersymmetry involving the pair production of gluinos decaying via third-generation squarks to the lightest neutralino is reported. It uses an LHC proton--proton dataset at a center-of-mass energy $\sqrt{s} = 13$ TeV with an integrated luminosity of 3.2 fb$^{-1}$ collected with the ATLAS detector in 2015. The signal is searched for in events containing several energetic jets, of which at least three must be identified as $b$-jets, large missing transverse momentum and, potentially, isolated electrons or muons. Large-radius jets with a high mass are also used to identify highly boosted top quarks. No excess is found above the predicted background. For neutralino masses below approximately 700 GeV, gluino masses of less than 1.78 TeV and 1.76 TeV are excluded at the 95% CL in simplified models of the pair production of gluinos decaying via sbottom and stop, respectively. These results significantly extend the exclusion limits obtained with the $\sqrt{s} = 8$ TeV dataset.