  Cross sections for physical processes that involve very different momentum
scales in the same process will involve large logarithms of the ratio of the
momentum scales when calculated in perturbation theory. One goal of
calculations using parton showers is to sum these large logarithms. We ask
whether this goal is achieved for the transverse momentum distribution of a
Z-boson produced in hadron-hadron collisions when the shower is organized with
higher virtuality parton splittings coming first, followed successively by
lower virtuality parton splittings. We find that the virtuality ordered shower
works well in reproducing the known QCD result.
