2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/197425Effective field theories with (large) extra dimensions are studied within a physical regularization scheme provided by string theory. Explicit string calculations then allow us to consistently analyze the ultraviolet sensitivity of Kaluza--Klein theories in the presence or absence of low energy supersymmetry.50 pages, LaTeXHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext