Theoretical aspects of W-pair production in e+e- collisions

Abstract

The most interesting theoretical features of W-pair production in e+e- collisions are reviewed. Based on an analysis of on-shell W-pairs, it is shown that the mere inclusion of leading $O(\alpha )$ corrections--such as initial-state radiation, effects from the universal quantities $\Delta \alpha$ and $\Delta r$, and the Coulomb singularity--cannot be expected to approximate the $O(\alpha )$-corrected cross-section of $e^{+}{e}^{-}\to W^{+}{W}^{-}\to 4f$ to better than 1-2% for LEP2 energies. The importance of the gauge-invariance problem, arising from the introduction of finite decay widths, is discussed. The simplest consistent method to include $O(\alpha )$ corrections at least to the doubly resonant contributions, viz. a pole expansion around the double resonance, is also briefly described.

19 pages, latex, 5 postscript figures included, talk given at the 3rd International Symposium on Radiative Corrections, Cracow, Poland, August 1-5, 1996