Measurement of spin correlations in ttproduction using the matrix element method in the muon+jets final state in pp collisions at √s=8TeV

Abstract

The consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8TeV, corresponding to an integrated luminosity of 19.7fb−1. The data are compared with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72 ±0.08 (stat)+0.15−0.13(syst), representing the most precise measurement of this quantity in the muon+jets final state to date.