Search for light top squark pair production in final states with leptons and b-jets with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions

TL;DR

This paper reports a search for light top squark pair production in proton-proton collisions at 7 TeV using the ATLAS detector, finding no evidence of such particles and setting exclusion limits on their masses.

Contribution

It introduces a novel search strategy targeting specific final states to identify light top squarks and sets new exclusion limits within the MSSM framework.

Findings

No excess over Standard Model expectations was observed.

Light top squarks with masses between 123-167 GeV are excluded.

The analysis constrains supersymmetric models with specific decay assumptions.

Abstract

The results of a search for pair production of light top squarks are presented, using 4.7 fb^-1 of sqrt(s) = 7 TeV proton-proton collisions collected with the ATLAS detector at the Large Hadron Collider. This search targets top squarks with masses similar to, or lighter than, the top quark mass. Final states containing exclusively one or two leptons (e, mu), large missing transverse momentum, light-jets and b-jets are used to reconstruct the top squark pair system. Global mass scale variables are used to separate the signal from a large ttbar background. No excess over the Standard Model expectations is found. The results are interpreted in the framework of the Minimal Supersymmetric Standard Model, assuming the top squark decays exclusively to a chargino and a b-quark. Light top squarks with masses between 123-167 GeV are excluded for neutralino masses around 55 GeV.