Measurement of the Angular Distribution of Electrons from W->e nu Decays Observed in ppbar Collisions at sqrt(s)=1.8 TeV

TL;DR

This paper measures the angular distribution of electrons from W boson decays in proton-antiproton collisions to test next-to-leading order QCD predictions and improve understanding of W mass measurements.

Contribution

First measurement of the electron angular distribution parameter alpha_2 as a function of W transverse momentum in proton-antiproton collisions.

Findings

Measured alpha_2 varies with W transverse momentum.

Results agree with next-to-leading order QCD predictions.

Provides data to refine W mass measurements.

Abstract

We present the first measurement of the electron angular distribution parameter alpha_2 in W to 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 D0 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 cos theta* + alpha_2 cos^2 theta*), where 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.