Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using $\sqrt{s}=8$ TeV proton--proton collision data

TL;DR

This paper reports a search for supersymmetric particles, specifically squarks and gluinos, using 8 TeV proton-proton collision data from ATLAS, finding no evidence of new physics and setting new exclusion limits on their masses.

Contribution

It provides the first comprehensive set of exclusion limits on squark and gluino masses using 8 TeV data, improving constraints on supersymmetry models.

Findings

Gluino mass excluded up to 1330 GeV

Squark masses below 850 GeV excluded for certain models

Extended the supersymmetry parameter space exclusion region

Abstract

A search for squarks and gluinos in final states containing high-$p_{\rm T}$ jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in $\sqrt{s}=8$ TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of $20.3 \mathrm{fb}^{-1}$. No significant excess above the Standard Model expectation is observed. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with $\tan\beta=30$, $A_0=-2m_0$ and $\mu> 0$, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.