A Simple Flavor Protection for RS

TL;DR

This paper introduces a simplified warped flavor model with two horizontal U(1) symmetries that suppress dangerous flavor violations in the Kaon sector, allowing for a KK scale around 3 TeV while maintaining fermion mass hierarchies.

Contribution

It proposes a novel variation of warped flavor models using two U(1) symmetries to reduce flavor violation, especially in the Kaon sector, with detailed analysis of flavor constraints including kinetic mixing effects.

Findings

Flavor violation in the down sector is suppressed except for small kinetic mixing.

D - anti-D mixing constraints are satisfied at a KK scale of about 3 TeV.

The model's flavor constraints are compatible with new U(1) gauge bosons.

Abstract

We present a simple variation of warped flavor models where the hierarchies of fermion masses and mixings are still explained but dangerous flavor violating effects in the Kaon sector are greatly reduced. The key new ingredients are two horizontal U(1) symmetries. These symmetries forbid flavor violation in the down quark sector (with the exception of small IR brane localized kinetic mixing terms for the left-handed quarks) while allowing for flavor violation in the up quark sector. The leading flavor constraints come from D - anti-D mixing, and are safely satisfied for the KK mass scale of order 3 TeV. Our analysis of the flavor constraints also includes the constraints due to the (usually ignored) localized kinetic mixing terms. We also comment on the effects of the additional U(1) gauge bosons.