2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51024Unabridged version of the Thesis presented to the University of L' Aquila, in partial fulfillment of the requirements for the ``Laurea'' degree in Physics, October 1998. Work carried out at the University of L'Aquila and at the University of Rome ``Tor Vergata''.In ItalianHigh Energy Physics - Theorytext