Top quark Kaluza - Klein mode mixing in the Randall - Sundrum bulk Standard Model and B →

We study top quark Kaluza-Klein (KK) mode mixing in the Randall-Sundrum scenario with all the SM fermions and gauge bosons in the bulk. Even though the simple assumption of universal bulk fermion mass mψ leads to the same KK mass spectrum for all the SM fermions and thus suppresses new contributions to the flavor changing neutral current and the ρ parameter, large Yukawa coupling of the top quark generates the mixing among its KK modes and breaks the degeneracy: Unacceptably large contribution to ∆ρ occurs. In order to satisfy the ∆ρ constraint, we relax the model by assigning a different bulk fermion mass to SU(2) singlet bottom quark, and demonstrate that there exists some limited parameter space where the ∆ρ constraint is satisfied. It is also shown that the current measurement of Br(B → Xs + γ) can be accommodated in this modified model, and one sigma level precision constrains the effective weak scale kEW such as kEW > ∼ 3 TeV for mψ/k = −0.4, where kEW is the warp-suppressed AdS5 curvature.