Measurement of the angular distribution of electrons from W boson decays at D-zero.

Abstract

We present a measurement of the electron angular distribution parameter a2 in W→ en events using data collected by the DO detector during the 1994--1995 Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of ( 1+/-a1cosq* +a2cos 2q* ), where q* is the angle between the charged lepton and the antiproton in the Collins-Soper frame. In the presence of QCD corrections, the parameters a1 and a2 become functions of pWT , the W boson transverse momentum. We present the first measurement of a2 as a function of pWT . This measurement is of importance, because it provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W mass measurement.