Suppression of flavor violation in an A4 warped extra dimensional model

TL;DR

This paper demonstrates that a warped extra-dimensional model with A4 flavor symmetry can suppress flavor violation effects, allowing for lower KK mass scales while maintaining realistic quark and lepton mixing patterns.

Contribution

It extends previous models by analyzing full flavor structures beyond the zero mode approximation, showing how A4 symmetry relaxes flavor violation constraints in RS models.

Findings

Suppressed flavor-changing neutral currents in the model.

Relaxed bounds on Kaluza-Klein mass scale compared to anarchic models.

Achieved realistic quark and lepton mixing patterns with flavor symmetry.

Abstract

In an attempt to simultaneously explain the observed masses and mixing patterns of both quarks and leptons, we recently proposed a model (JHEP08(2010)115) based on the non abelian discrete flavor group A4, implemented in a custodial RS setup with a bulk Higgs. We showed that the standard model flavor structure can be realized within the zero mode approximation (ZMA), with nearly tribimaximal (TBM) neutrino mixing and a realistic CKM matrix with rather mild assumptions. An important advantage of this framework with respect to flavor anarchic models is the vanishing of the dangerous tree level KK gluon contribution to \epsilon_K and the suppression of the new physics one loop contributions to the neutron EDM, \epsilon'/\epsilon, b->s\gamma and Higgs mediated flavor changing neutral current (FCNC) processes. These results are obtained beyond the ZMA, in order to account for the the full flavor structure and mixing of the zero modes and first Kaluza-Klein (KK) modes of all generations. The resulting constraints on the KK mass scale are shown to be significantly relaxed compared to the flavor anarchic case, showing explicitly the role of non abelian discrete flavor symmetries in relaxing flavor violation bounds within the RS setup. As a byproduct of our analysis we also obtain the same contributions for the custodial anarchic case with two SU(2)_R doublets for each fermion generation.