QED Interconnection Effects on W Momentum Distributions at LEP 2

Abstract

The process $\text{ee}\to {\text{W}}^{+}{\text{W}}^{-}\to {\text{f}}_1{\text{fbar}}_2{\text{f}}_3{\text{fbar}}_4$ contains charges in the initial, intermediate and final stages. This gives a rich selection of possible QED interconnection effects. Coulomb interaction is the simplest of these, and can thus be used to explore consequences. We study a number of experimental observables, with emphasis on those related to the W momentum distribution. Second-order Coulomb effects are shown to be practically negligible. The limited LEP~2 statistics will not allow detailed tests, so any theory uncertainty will be reflected in the systematic error on the W mass. Currently the uncertainty from this source may be as high as 20~MeV.

Comments: 1+27 pages, including 23 eps figures, use uudecode and gunzip to restore original file, run LaTeX2epsilon with epsfig package, figures are included in filecontents environments; alternatively ready-made postscript file is available at http://thep.lu.se/tf2/staff/torbjorn/Welcome.html