Measurement of the Electric Charge of the Top Quark in $\boldsymbol{t\bar{t}}$ Events

TL;DR

This paper measures the electric charge of the top quark in proton-antiproton collisions, strongly supporting the Standard Model value and excluding exotic charge hypotheses with high statistical significance.

Contribution

It provides the first high-confidence exclusion of the exotic charge hypothesis for the top quark using fully reconstructed $tar{t}$ events at the Tevatron.

Findings

Excludes top quark charge of $Q=-4/3 e$ at >5 sigma significance.

Places an upper limit of 0.46 on admixture of exotic charge top quarks.

Supports the Standard Model top quark charge of $+2/3 e$.

Abstract

We present a measurement of the electric charge of top quarks using $t\bar{t}$ events produced in $p\bar{p}$ collisions at the Tevatron. The analysis is based on fully reconstructed $t\bar{t}$ pairs in lepton+jets final states. Using data corresponding to 5.3 $\rm fb^{-1}$ of integrated luminosity, we exclude the hypothesis that the top quark has a charge of $Q=-4/3\,e$ at a significance greater than 5 standard deviations. We also place an upper limit of 0.46 on the fraction of such quarks that can be present in an admixture with the standard model top quarks ($Q=+2/3\,e$) at a 95\% confidence level.