Khachatryan, V.Işıldak, Bora2016-06-292016-06-292016-041029-8479http://hdl.handle.net/10679/4090https://doi.org/10.1007/JHEP04(2016)073A 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.engrestrictedAccessarticle400037433970000110.1007/JHEP04(2016)073Hadron-hadron scattering (experiments)Top physics2-s2.0-84963893819