2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/112498This is the introduction to the PhD thesis, defended in June 2006. In the original form it was appended with the reprints of the author's published papers, and is to be regarded as their summary. Full details may be found in the quoted papers.57 pages, PhD thesisHigh Energy Physics - Phenomenologytext