THEORETICAL ASPECTS OF W-PAIR PRODUCTION IN E(-) COLLISIONS()E()

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 expect ed to approximate the O(alpha)-corrected cross-section of e(+)e(-) --> WW --> 4f to better than 1-2% for LEP2 energies. The importance of th e gauge-invariance problem, arising from the introduction of finite de cay 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 describe d.