Journal of High Energy Physics
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.
Baarmand, M M.; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Kalakhety, H; Noonan, D; Roy, Tuhin S.; Yumiceva, Francisco X.; and CMS Collaboration, "Measurement Of Top Quark Polarisation In t-Channel Single Top Quark Production" (2016). Aerospace, Physics, and Space Science Faculty Publications. 46.