2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/202605We analyze the ultraviolet stability of the Higgs mass in recently proposed Kaluza-Klein models compactified on S_1/Z_2 or S_1/(Z_2\times Z_2'), both at the field theory and string theory level. Fayet-Iliopoulos terms of U(1) hypercharge are shown to be of vital importance for this discussion. Models with a single Higgs doublet seem to be generically affected by quadratic divergences.Contribution to the Proceedings of Durham IPPP meeting May 2001.(12 pages, LaTeX)High Energy Physics - PhenomenologyHigh Energy Physics - Theorytext