Measurement of top quark polarization in $t \overline{t}$ lepton+jets final states

TL;DR

This paper measures the polarization of top quarks in proton-antiproton collisions at 1.96 TeV, using lepton+jets final states, and finds results consistent with the Standard Model, including the first transverse polarization measurement at the Tevatron.

Contribution

First measurement of top quark polarization in lepton+jets final states at the Tevatron, including transverse polarization in top-antitop production.

Findings

Distributions consistent with Standard Model predictions

First measurement of transverse polarization in top-antitop production at the Tevatron

Utilized lepton and jet angular distributions for polarization measurement

Abstract

We present a study of top quark polarization in $t \overline{t}$ events produced in $p \overline{p}$ collisions at $\sqrt{s}=1.96$ TeV. Data correspond to 9.7 fb$^{-1}$ collected with the D0 detector at the Tevatron. We use final states containing a lepton and at least three jets. The polarization is measured using the distribution of leptons along the beam and helicity axes, and the axis normal to the production plane. This is the first measurement of top quark polarization at the Tevatron in $\ell$+jets final states, and first measurement of transverse polarization in $t \overline{t}$ production. The observed distributions are consistent with the standard model.