A Solution to the Flavor Problem of Warped Extra-Dimension Models

Abstract

A minimal solution to the flavor problem of warped extra-dimension models, i.e. the excessive mixed-chirality contribution to CP violation in K-Kbar mixing arising from Kaluza-Klein (KK) gluon exchange, is proposed. Extending the strong-interaction gauge group in the bulk by an additional SU(3), and breaking this symmetry to QCD via boundary conditions, the constraints arising from the epsilon_K parameter are significantly relaxed. As a result, KK scales M_KK ~ 2 TeV are consistent with all flavor observables without significant fine-tuning. The model predicts the existence of an extended Higgs sector featuring massive color-octet scalars and a tower of KK pseudo-axial gluon resonances, whose existence is not in conflict with recent LHC dijet bounds.

Added discussion of the extended scalar sector and its impact on the choice of boundary conditions. Corrected the Wilson coeffcients in (12) by a symmetry factor of 1/2 and updated the plots in Figure 2 with improved fitting functions. Main conclusions unchanged