W and Z production at pp-bar colliders: Parton showers merged with O( alpha s) Monte Carlo approach.

Abstract

We construct event generators for $p\overline{p}\ensuremath{\rightarrow}{W}^{+}X\ensuremath{\rightarrow}{e}^{+}\ensuremath{\nu}X$ and $p\overline{p}\ensuremath{\rightarrow}{Z}^{0}X\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}X$ including complete $O({\ensuremath{\alpha}}_{s})$ corrections, and interface with initial- and final-state parton showers. Problems with negative weights and double-counting multiple-parton emissions are averted. We calculate the ${q}_{T}(W)$ spectrum at both $\sqrt{s}=0.63$ TeV and $\sqrt{s}=1.8$ TeV, and compare with data and other theoretical predictions. We also present cross sections for the various $W$ or $Z$ plus multijet event topologies and compare with matrix-element results. We show several distributions associated with $W+\mathrm{multijet}\mathrm{events}$ and find the jet rapidity distribution can be used to test the validity of our approach.