Search for admixture of scalar top quarks in the ttbar lepton+jets final state at sqrt(s)=1.96 TeV

TL;DR

This paper reports a search for scalar top quark pairs in proton-antiproton collisions, using kinematic analysis to distinguish potential signals from background, and sets new limits on their masses based on Tevatron data.

Contribution

It introduces a novel analysis method to differentiate scalar top quark pair production from top quark pairs and provides the first limits for certain mass ranges at the Tevatron.

Findings

No evidence of scalar top quark production was observed.

Limits on scalar top quark masses were set between 130-190 GeV.

Limits on chargino masses were established between 90-150 GeV.

Abstract

A search for pair production of the lightest supersymmetric partner of the top quark is performed in the lepton+jets channel using 0.9 fb-1 of data collected by the D0 experiment. Kinematic differences between scalar top quark pair production and the dominant top quark pair production background are used to separate the two processes. First limits from Run II of the Fermilab Tevatron Collider for the scalar top quark decaying to a chargino and a b quark are obtained for scalar top quark masses of 130-190 GeV and chargino masses of 90-150 GeV.