Semi-analytical and Monte Carlo results for the production of four   fermions in $e^+ e^-$ collisions
  In view of the forthcoming experiments at high energy $e^+ e^-$ colliders, LEP2 and beyond, the process $e^+ e^- \to W^+ W^- \to 4f$ has been investigated for {\it off-shell} $W$'s. After deriving the matrix element for the process within the helicity amplitude formalism, QED radiative corrections to the initial state leptons have been included at the leading logarithmic level in the framework of the electron structure functions. Cross sections and distributions are computed by means of both a semi-analytical and a Monte Carlo code, allowing for several cuts of experimental interest. A Monte Carlo event generator has also been built, for simulation purposes. Some illustrative numerical results are included and shortly described. 
G.Montagna, O.Nicrosini, G.Passarino, F.Piccinini