We present a measurement of top quark polarization in $t\overline{t}$ pair production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using data corresponding to $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. We consider final states containing a lepton and at least three jets. The polarization is measured through the distribution of lepton angles along three axes: the beam axis, the helicity axis, and the transverse axis normal to the $t\overline{t}$ production plane. This is the first measurement of top quark polarization at the Tevatron using $\mathrm{lepton}+\text{jet}$ final states and the first measurement of the transverse polarization in $t\overline{t}$ production. The observed distributions are consistent with standard model predictions of nearly no polarization.
Tópico:
Particle physics theoretical and experimental studies