SINGLE WEAK BOSON PRODUCTION AT TEV E+E- COLLIDERS

We present exact tree level matrix elements for all the single weak boson production processes to order e3 in very high energy e+e- collisions; e+e- --> e +/- nu-e(-)W -/+, e+e-Z, nu-e-nu-BAR-e(Z) and gamma-gamma-Z. The electron mass is kept finite so that the differential and total cross sections are accurate up to terms of order m(e)2/s. The weak boson distributions are compared with those obtained by the equivalent photon/electron approximation (EPA), which works reasonably well at high vector boson transverse momenta but fails at small transverse momenta for the processes e+e- --> e+e-Z and gamma-gamma-Z. A simple modification of the EPA formulae is found to give a reasonable overall description of the distributions for all the single weak boson production processes. Electron helicity-flip amplitudes are found to contribute at the percent level at most, which can be reproduced accurately by a novel collinear approximation with equivalent real photon or electron distributions in an electron. Interference effects between the annihilation and non-annihilation diagrams are found to be significant only below the weak boson pair production threshold. Also explained is a straightforward method to incorporate the leptonic and parton level hadronic decays of the weak bosons into the production amplitudes.