Study of Top Quark Spin with the CMS Experiment at LHC

Study of Top Quark Spin with the CMS Experiment at LHC by Hamit Mermerkaya Dissertation Advisor: Marc Baarmand, Ph.D. Since the top quark decays before either hadronization or depolarization, and its spin flip time is much larger than its lifetime, the spin properties of the top and anti-top quarks are reflected directly in the angular distribution of the jets and leptons into which they decay. These distributions are determined by t and t polarizations and the spin correlations induced by the production mechanisms and depend on the interactions responsible for heavy quark decay. This thesis presents the measurements of spin correlation in top quark pair production and spin polarization in t-channel single top quark production in proton-proton collisions at √ s = 10 TeV with the CMS detector at LHC. Using simulations of muon plus jets decay of the top quark pair with the CMS detector response, and based on a total integrated luminosity of two inverse femtobarn, the spin asymmetry coefficient for top quark pair production can be measured with a total uncertainty of 25% including the systematic errors.