Search for a supersymmetric partner to the top quark in final states with jets and missing transverse momentum at sqrt(s) = 7 TeV with the ATLAS detector

TL;DR

This paper reports a search for supersymmetric top squarks in proton-proton collisions at 7 TeV, analyzing events with jets and missing transverse momentum, setting exclusion limits on their masses based on observed data versus Standard Model predictions.

Contribution

The study provides new exclusion limits on the masses of top squarks and neutralinos using ATLAS data, advancing the search for supersymmetry in hadronic final states.

Findings

Excluded top squark masses between 370 and 465 GeV for neutralino mass near zero.

Excluded a top squark mass of 445 GeV for neutralino masses up to 50 GeV.

Observed event counts are consistent with Standard Model background predictions.

Abstract

A search for direct pair production of supersymmetric top squarks (stop_1) is presented, assuming the stop_1 decays into a top quark and the lightest supersymmetric particle, neutralino_1, and that both top quarks decay to purely hadronic final states. A total of 16 (4) events are observed compared to a predicted Standard Model background of 13.5+3.7-3.6 (4.4+1.7-1.3) events in two signal regions based on int(Ldt) = 4.7 fb^-1 of pp collision data taken at sqrt(s) = 7 TeV with the ATLAS detector at the LHC. An exclusion region in the stop_1 versus neutralino_1 mass plane is evaluated: 370<m(stop_1)<465 GeV is excluded for m(neutralino_1)~0 GeV while m(stop_1)=445 GeV is excluded for m(neutralino_1)<=50 GeV.