Measurement of the angular distribution of electrons from W→eν decays observed in p(p)over-bar collisions at √s=1.8 TeV

We present the first measurement of the electron angular distribution parameter alpha(2) in W --> ev events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the DO detector during the 1994-1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1 +/- alpha(1) COStheta* + alpha(2) COS(2)theta*), where theta* is the polar angle of the electron in the Collins-Soper frame and alpha(1) and alpha(2) are functions of p(T)(W), the W boson transverse momentum. This measurement provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W boson mass measurement.