$e^+e^-\to b\bar bW^+W^-$ at the Next Linear Collider, Top-Pairs and   Higgs Production
  The complete matrix element for $e^+e^-\ar W^+W^-\bar b b$ is computed at tree level and applied to: {\bf a)} $\bar t t$ production and decay ; {\bf b)} $ZH$ production followed by $Z\ar \bar bb$ and $H\ar WW$. In both cases we include finite width effects and all irreducible backgrounds. 
A. Ballestrero, E. Maina and S. Moretti (U. of Torino)