Abbott, B (reprint author), NYU, New York, NY 10003 USA.
We present the first measurement of the electron angular distribution parameter alpha (2) in W-->e nu events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the D empty set detector during the 1994-1995 Fermilab Tevatron run. We compare our results with next-to-leadiog order perturbative QCD, which predicts an angular distribution of (1 +/- alpha (1) cos theta* + alpha (2) cos(2) theta*), whew theta* is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters alpha (1) and alpha (2) become 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.