2016/11/28 by Andres Tiko, Tiko, Andres
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #hep-ex
paper · pdf · doi:10.48550/arxiv.1611.09397
presented at 9th International Workshop on Top Quark Physics Olomouc, Czech Republic, September 19–23, 2016
arxiv created 2016/11/28 · arxiv updated 2016/12/04
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 \mathrmfb-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 \textrm(stat) ± 0.10 \textrm(syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.