Measurement of [gamma](1S) spin alignment with the CMS detector

Abstract

This thesis presents a measurement of the spin alignment of prompt [gamma](1S) mesons produced in proton-proton collisions at [square root of]s = 7 TeV at the Large Hadron Collider using the Compact Muon Solenoid detector. Approximately 1 fb-1 of data taken during the year 2011 is analyzed. The decay to two muons is used to identify these decays, and the angular distribution of the two muons is measured. The method is designed to measure the tensor polarization with minimal assumptions about the production mechanism involved. The decay distribution of the muons is measured in the full two dimensional angular space as a function of the transverse momentum and rapidity of the [gamma], and the analysis is repeated in the helicity and Collins-Soper frames. A frame invariant quantity is calculated in each frame from the measured decay distribution and compared. The final result disfavors large polarization, but suggests the presence of some anisotropy in the decay