title: Difficulties for five-dimensional gauge-higgs unification.
abstract: We consider five-dimensional gauge theories where all fields propagate in the bulk and the fifth direction is compactified on the orbifold S1/Z2, and where the fifth components of the gauge bosons play the role of the standard model Higgs boson (gauge-Higgs unification). The gauge symmetry breaking is realized through the appropriate orbifold boundary conditions and through the Hosotani mechanism. We show that for any such theory (with neither brane gauge kinetic terms nor anomalous gauge-group factors) the assumption that the low-energy vector-boson spectrum consists of the W(+/-), Z, and gamma only, is inconsistent with the experimental requirements sin2thetaW approximately 1/4 and rho identical with mW2/(mZ2 cos2theta w) = 1.
authors.affiliation: Institute of Theoretical Physics, Warsaw University, Hoza 69, PL-00-681 Warsaw, Poland. bohdan. grzadkowski@fuw.edu.pl
authors.forename: Bohdan
authors.initials: B
authors.lastname: Grzadkowski
authors.forename: José
authors.initials: J
authors.lastname: Wudka