Measurement of the transverse momentum distribution of Z bosons in proton-proton collisions at √s = 7TeV using the ATLAS detector

Abstract

Z boson production at the LHC presents a good opportunity to test Standard Model predictions. This thesis reports the measurement of the Z boson transverse momentum distribution in proton-proton collisions at sqrt(s)=7TeV, inclusive in Z rapidity and subdivided in three rapidity intervals. The measurement uses data taken with the ATLAS detector in 2011 corresponding to an integrated luminosity of 4.7fb-1, from which 1.8 million events with Z bosons decaying into muon pairs are selected. After subtracting the expected background distribution, the transverse momentum distribution of candidate events is unfolded to the Born level, correcting for efficiency and resolution effects as well as QED final state radiation. The transverse momentum distribution is measured up to a transverse momentum of 800GeV with a precision of <1.5% for pt<150GeV. The measurement is compared with higher order perturbative QCD predictions and common parton shower event generators. The prediction from resummed QCD combined with fixed order perturbative QCD provides a good description of the measurement. The measured cross sections provide an important input to the tuning of parton shower event generators.