Quadratic divergences in Kaluza-Klein theories

We investigate the so-called "Kaluza-Klein regularisation" procedure in sup ersymmetric extensions of the standard model with additional compact dimens ions and Scherk-Schwarz mechanism for supersymmetry breaking. This procedur e uses a specific mathematical manipulation to obtain a finite result for t he scalar potential. By performing the full calculation, we show that the f initeness of this result is not only a consequence of the underlying supers ymmetry, but also the result of an implicit fine-tuning of the coefficients of the terms that control the ultraviolet behaviour The finiteness of the Higgs mass at one-loop level seems therefore to be an artefact of the regul arisation scheme, and quadratic divergences are expected to reappear in hig her orders of perturbation theory. (C) 2001 Published by Elsevier Science B .V.