Bulk gauge fields in the Randall–Sundrum model

We explore the consequences of placing the Standard Model gauge fields in the bulk of the recently proposed localized gravity model of Randall and Sundrum. We find that the Kaluza–Klein excitations of these fields are necessarily strongly coupled and we demonstrate that current precision electroweak data constrain the lowest states to lie above ≃23 TeV. Taking the weak scale to be ∼1 TeV, the resulting implications on the model parameters force the bulk curvature, R5, to be larger than the higher dimensional Planck scale, M, violating the consistency of the theory. In turn, to preserve |R5|≲M2, the weak scale must be pushed to ≳100 TeV. Hence we conclude that it is disfavored to place the Standard Model gauge fields in the bulk of this model as it is presently formulated.