Experimental discrimination between charge 2e/3 top quark and charge 4e/3 exotic quark production scenarios

TL;DR

This study experimentally distinguishes between the standard top quark charge of 2e/3 and an exotic 4e/3 charge scenario using collision data, providing the first such discrimination at the Tevatron.

Contribution

It introduces a method to differentiate top quark charge scenarios using jet charge and momentum analysis in proton-antiproton collisions, with experimental limits set on exotic quark production.

Findings

Data is consistent with the standard charge |q|=2e/3.

Excludes pure exotic 4e/3 quark production at 92% confidence level.

Places an upper limit of 0.80 on the fraction of exotic quark pairs at 90% confidence level.

Abstract

We present the first experimental discrimination between the 2e/3 and 4e/3 top quark electric charge scenarios, using top quark pairs (ttbar) produced in ppbar collisions at sqrt{s}=1.96 TeV by the Fermilab Tevatron collider. We use 370 pb-1 of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and bbar-quark jets by using the charge and momenta of tracks within the jet cones. The data is consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs QQbar with |q|=4e/3. We place an upper limit on the fraction of QQbar pairs fq < 0.80 at the 90% C.L.