Four leptons final states from $\gamma\gamma$ fusion

Abstract

I present a systematic study of all possible four leptons final states from $\gamma\gamma$ collisions. It is given a detailed account of fermion masses effects which are sizable since several collinear and $t$ channel enancements occur. The effects of angular cuts on the final charged leptons are also discussed. To perform the computation I have used the recently developed ALPHA algorithm (and the resulting code) for the automatic computation of scattering amplitudes.