Particle Physics Seminar

Abstract: 

I present a  measurement of the effective leptonic weak mixing angle using the forward-backward asymmetry of Drell–Yan lepton pairs (µµ and ee) produced in proton-proton collisions at 8 TeV at the CMS experiment of the LHC. The data correspond to integrated luminosities of 18.8 and 19.6 fb−1 in the dimuon and dielectron channels, respectively, containing 8.2 million dimuon and 4.9 million dielectron events. With more events and new analysis techniques, including constraints obtained on the parton distribution functions from the measured forward-backward asymmetry, the statistical and systematic uncertainties are significantly reduced relative to previous CMS measurements. The extracted value of weak mixing angle from the combined dilepton data is  0.23101 ± 0.00036 (stat) ± 0.00018 (syst) ± 0.00016 (theo) ± 0.00031 (parton distributions in proton)  or 0.23101 ± 0.00053. The uncertainty in the measurement at 13 TeV (currently under analysis) is expected to be a about factor of 2 smaller.

Seminar Organizer: Prof. Nissan Itzhaki