Measurement of the phistar distribution of Z bosons decaying to electron pairs with the CMS experiment at a center-of-mass energy of 8 TeV

Abstract

Measurements of the Z boson transverse momentum (Qt) spectrum serves as both a precision test of non-perturbative QCD and helps to reduce the uncertainty in the measurement of the W boson mass. However, Qt is limited at its lowest values by detector resolution, and so a new variable, phistar, which performs better in the low Qt region, is used instead. This thesis presents the first measurement of the normalized differential cross section of Z bosons decaying to electron pairs in terms of phistar at a center-of-mass energy of 8 TeV. The data used in this measurement were collected by the CMS detector at the LHC in 2012 and totaled 19.7/fb of integrated luminosity. The results are compared to predictions from simulation, which are found to provide a poor description of the data.