Search for light scalar top quark pair production in final states with two leptons with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions

TL;DR

This paper reports a search for light scalar top quark pairs in proton-proton collisions at 7 TeV using the ATLAS detector, analyzing 4.7 fb-1 of data, and sets exclusion limits on their masses.

Contribution

It presents the first search for light scalar top quarks in final states with two leptons at 7 TeV with the ATLAS detector, setting new mass exclusion limits.

Findings

No excess over Standard Model expectations was observed.

Scalar top quarks with masses up to 130 GeV are excluded for certain neutralino masses.

The analysis constrains supersymmetric models involving light scalar top quarks.

Abstract

A search is presented for the pair production of light scalar top quarks in sqrt(s) = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. This analysis uses the full data sample collected during 2011 that corresponds to a total integrated luminosity of 4.7 fb-1. Light scalar top quarks are searched for in events with two opposite-sign leptons (e, mu), large missing transverse momentum and at least one jet in the final state. No excess over Standard Model expectations is found, and the results are interpreted under the assumption that the light scalar top decays to a b-quark in addition to an on-shell chargino whose decay occurs through a virtual W boson. If the chargino mass is 106 GeV, light scalar top quark masses up to 130 GeV are excluded for neutralino masses below 70 GeV.