SM Kaluza-Klein excitations and electroweak precision tests

We consider a minimal extension to higher dimensions of the Standard Model, having one compactified dimension, and we study its experimental tests in terms of electroweak data. We discuss tests from high-energy data at the Z- pole, and low-energy tests, notably from atomic parity violation data. This measurement combined with neutrino scattering data strongly restricts the allowed region of the model parameters. Furthermore this region is incompat ible at 95% CL with the restrictions from high-energy experiments. Of cours e a global fit to all data is possible but the chi(min)(2) for degree of fr eedom is unpleasantly large. (C) 1999 Published by Elsevier Science B.V. Al l rights reserved.