Six-fermion production and Higgs boson physics at future e(+)e(-) colliders

The six-fermion production processes e(+)e(-) --> q (q) over bar l(+)l(-) v (v) over bar, with all the lepton flavours and q = u, d, c, s, relevant to the study of the intermediate-mass Higgs boson at future e(+)e(-) linear c olliders are analysed. A Monte Carlo program, taking into account the whole set of tree-level scattering amplitudes and the relevant radiative effects , is developed to provide integrated cross-sections and generation of unwei ghted events. The complete calculation is compared with the available resul ts of real Higgs production, and the opportunities of precision studies wit h event generation are discussed, demonstrating the relevance of a full six -fermion calculation. Numerical results for integrated cross-sections with various kinematical cuts and including radiative effects are given and comm ented. In the analysis of event samples, several distributions are studied and found to be sensitive to the presence and to the properties of the Higg s boson.