Production of Single W Bosons at \sqrt{s}=189 GeV and Measurement of WWgamma Gauge Couplings

TL;DR

This paper reports on the measurement of single W boson production cross-section at 189 GeV and constrains WWgamma gauge couplings, confirming consistency with the Standard Model.

Contribution

It provides the first measurement of single W production cross-section at this energy and sets limits on WWgamma gauge couplings using LEP data.

Findings

Measured cross-section: 0.53 pb with uncertainties

Determined gauge couplings: kappa_gamma and lambda_gamma

Results are consistent with Standard Model predictions

Abstract

Single W boson production in electron-positron collisions is studied with the L3 detector at LEP. The data sample collected at a centre-of-mass energy of \sqrt{s} = 188.7GeV corresponds to an integrated luminosity of 176.4pb^-1. Events with a single energetic lepton or two acoplanar hadronic jets are selected. Within phase-space cuts, the total cross-section is measured to be 0.53 +/- 0.12 +/- 0.03 pb, consistent with the Standard Model expectation. Including our single W boson results obtained at lower \sqrt{s}, the WWgamma gauge couplings kappa_gamma and lambda_gamma are determined to be kappa_gamma = 0.93 +/- 0.16 +/- 0.09 and lambda_gamma = -0.31 +0.68 -0.19 +/- 0.13.