CP violation and FCNC in a warped A4 flavor model

TL;DR

This paper investigates a warped extra-dimensional A4 flavor model's phenomenology, focusing on flavor-changing neutral currents and deriving bounds on the Kaluza-Klein mass scale, showing it can be as low as 1.3 TeV without the little CP problem.

Contribution

It provides a systematic analysis of FCNC constraints in a warped A4 flavor model, including the effects of bulk Higgs and flavons, and establishes bounds on the KK mass scale.

Findings

Lower bound on KK scale M_{KK} > 1.3 TeV from FCNCs

Bound from Zb_Lar{b}_L is > 4.6 TeV

The model avoids the little CP problem present in flavor anarchic models

Abstract

We recently proposed a spontaneous A4 flavor symmetry breaking scheme implemented in a warped extra dimensional setup to explain the observed pattern of quark and lepton masses and mixings. The quark mixing is induced by bulk A4 flavons mediating "cross-brane" interactions and a "cross-talk" between the quark and neutrino sectors. In this work we explore the phenomenology of RS-A4 and systematically obtain bounds on the Kaluza-Klein (KK) mass scale implied by flavor changing neutral current (FCNC) processes. In particular, we study the constraints arising from Re(\epsilon'/\epsilon_K), b->s\gamma, the neutron EDM and Higgs mediated FCNCs, while the tree level contribution to \epsilon_K through a KK gluon exchange vanishes. We find an overall lower bound on the Kaluza-Klein mass scale M_{KK} > 1.3 TeV from FCNCs, induced by b->s\gamma, differently from flavor anarchic models. This bound is still weaker than the bound M_{KK} > 4.6 TeV induced by Zb_L\bar{b}_L in RS-A4. The little CP problem, related to the largely enhanced new physics contributions to the neutron EDM in flavor anarchic models, is absent. The subtleties of having the Higgs and flavons in the bulk are taken into account and final predictions are derived in the complete three-generation case.