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

V.M. Abazov , G. Sajot (1) , J. Stark (1) , S. Greder (2) , F. Miconi (2) , I. Ripp-Baudot (2) , U. Bassler (3) , G. Bernardi (4) , M. Besançon (3) , E. Chapon (5) , F. Couderc (3) , D. Brown (4) , F. Deliot (3) , Y. Enari (4) , A. Fauré (3) , G. Grenier (6) , A. Grohsjean (6) , T. Kurca (6) , P. Lebrun (6) , J. Lellouch (4) , D. Li (4) , V. Shary (3) , M. Titov (3) , B. Tuchming (3) , D. Vilanova (3) , F. Badaud (7) , Ph. Gris (7) , M.-C. Cousinou (8) , A. Duperrin (8) , W. Geng (8) , E. Kajfasz (8) , S. Kermiche (8) , E. Nagy (8) , N. Osman (8) , J.-F. Grivaz (9) , T. Guillemin (9) , P. Pétroff (9)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2 IPHC - Institut Pluridisciplinaire Hubert Curien
3 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
4 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
5 LLR - Laboratoire Leprince-Ringuet
6 IPNL - Institut de Physique Nucléaire de Lyon
7 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
8 CPPM - Centre de Physique des Particules de Marseille
9 LAL - Laboratoire de l'Accélérateur Linéaire

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.

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

V.M. Abazov, G. Sajot, J. Stark, S. Greder, F. Miconi, et al.. Measurement of top quark polarization in $t \overline{t}$ lepton+jets final states. Physical Review D, 2017, 95, pp.011101(R). ⟨10.1103/PhysRevD.95.011101⟩. ⟨in2p3-01349214⟩