Challenges in W-pair production
  The investigation of W-pair production offers unique precision tests of the electroweak theory at future e+e- colliders, including precise determinations of cross sections, the W-boson mass, and gauge-boson self-couplings. The state-of-the-art and future requirements in the theoretical prediction for the reaction e+e- -> WW -> 4f(+gamma) are briefly reviewed. 
A.Denner, S.Dittmaier, M.Roth and D.Wackeroth