Ultraviolet sensitivity of rare decays in nonuniversal extra dimensional models

Abstract

We consider a nonuniversal five-dimensional model in which fermions are localized on a four-dimensional brane, while gauge bosons and a scalar doublet can travel in the bulk. As a result of Kaluza-Klein number nonconservation at the brane-bulk intersection, the ultraviolet divergence does not cancel out in some physical observables. For example, the B_d → l⁺l⁻ decay amplitude is linearly divergent, while the B − ̅B mixing amplitude is log divergent. We attempt to identify the exact source of this nonrenormalizability. We compare and contrast our results with those obtained in the universal five-dimensional model where all particles travel in the extra dimension.