Studies of vector boson transverse momentum simulation in Monte Carlo event generators

We present studies of event generator behaviours regarding vector boson production characteristics, in particular the transverse momentum, pT, of the $Z$ boson as measured by ATLAS, for discussion at the LPCC working group meeting on precision electroweak physics at the LHC. The results discussed focus on the poor descriptions of ATLAS $W$ and $Z$ pT spectra by the ATLAS AUET2B LO** tune of PYTHIA6, and by the shower-matched NLO generator combination POWHEG+PYTHIA6. We show that both standalone PYTHIA6 and POWHEG can be made to describe the Sudakov peak of the ATLAS $Z$ pT distribution by tuning of the PYTHIA parton shower -- different approaches are required in each case. Comparisons of other NLO generators to the $Z$ pT data are also shown.