Opaque branes in warped backgrounds

We examine localized kinetic terms for gauge fields which can propagate into compact, warped extra dimensions. We show that these terms can have a relevant impact on the values of the Kaluza-Klein (KK) gauge field masses, wave functions, and couplings to brane and bulk matter. The resulting phenomenological implications are discussed. In particular, we show that the presence of opaque branes, with non-vanishing brane-localized gauge kinetic terms, allow much lower values of the lightest KK mode than in the case of transparent branes. Moreover, we show that if the large discrepancies among the different determinations of the weak mixing angle would be solved in favor of the value obtained from the lepton asymmetries, bulk electroweak gauge fields in warped-extra dimensions may lead to an improvement of the agreement of the fit to the electroweak precision data for a Higgs mass of the order of the weak scale and a mass of the first gauge boson KK excitation most likely within reach of the LHC.