Measurement of top quark polarisation in t-channel single top quark production


Khachatryan V., Sirunyan A., Tumasyan A., Adam W., Asilar E., Bergauer T., ...More

Journal of High Energy Physics, vol.2016, no.4, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 2016 Issue: 4
  • Publication Date: 2016
  • Doi Number: 10.1007/jhep04(2016)073
  • Journal Name: Journal of High Energy Physics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: Hadron-Hadron scattering (experiments), Top physics
  • Yıldız Technical University Affiliated: Yes

Abstract

A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. A differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 ± 0.03(stat) ± 0.10(syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.