Strong unitary violations in the extra dimensional SM and the   equivalence between Goldstone and longitudinal gauge bosons
  Tree level unitarity violations of extra dimensional extensions of the Standard Model may become much stronger when the scalar sector is included in the bulk. This effect occurs when the couplings are not suppressed for larger Kaluza-Klein levels, and could have relevant consequences for the phenomenology of the next generation of colliders. We briefly review our formalism to obtain more stringent unitarity bounds when KK modes are present, as well as the generalization to extra dimensions of the Equivalence Theorem between Goldstone bosons and longitudinal gauge bosons 
J.R. Pelaez (Complutense Univ. Madrid), S. De Curtis (INFN, Florence)   and D. Dominici (Florence U. and INFN Florence)