2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/188308We have investigated the gauge field of a fast moving projectile passing through a dense medium. We provide a simple and unified derivation, in light cone gauge, of the gluon production cross-section in proton-nucleus (initial state interactions), and the radiative gluon spectrum of a hard parton produced in a nucleus-nucleus collision (final state interactions). Finally, we discuss the validity of the eikonal approximation in proton-nucleus collisions at RHIC energies.8 pages, 2 figures. talk given at International Conference on Strong and Electroweak Matter (SEWM 2006), Upton, New York, 10-13 May 2006High Energy Physics - Phenomenologytext