2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46194I present a systematic study of all possible four leptons final states from $γγ$ 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.Plain latex (11 pages) plus six postcript figures (NOT included in the text and to be printed separately)High Energy Physics - Phenomenologytext