Minimal Flavor Violation in the Lepton Sector of the Randall-Sundrum Model

TL;DR

This paper introduces a model implementing Minimal Flavor Violation in the lepton sector within the Randall-Sundrum framework, reducing flavor-changing effects and allowing for a lower KK mass scale around 3 TeV.

Contribution

It demonstrates how MFV can be realized in the lepton sector of the Randall-Sundrum model, suppressing FCNCs and accommodating realistic lepton masses and mixings.

Findings

FCNCs are highly suppressed with massless neutrinos.

A KK mass scale as low as ~3 TeV is compatible with the model.

Numerical examples achieve realistic lepton masses and mixing angles.

Abstract

We propose a realization of Minimal Flavor Violation in the lepton sector of the Randall-Sundrum model. With the MFV assumption, the only source of flavor violation are the 5D Yukawa couplings, and the usual two independent sources of flavor violation are related. In the limit of massless neutrinos, the bulk mass matrices and 5D Yukawa matrices are simultaneously diagonalized, and hence the absence of FCNCs. In the case of massive neutrinos, the contributions to FCNCs in the charged lepton sector are highly suppressed, due to the smallness of neutrino masses. In addition, the MFV assumption also allows suppressing one-loop charged current contributions to flavor changing processes by reducing the size of the Yukawa couplings, which is not possible in the generic anarchical case. We found that the first KK mass scale as low as ~ 3 TeV can be allowed. In both cases, we present a set of numerical results that give rise to realistic lepton masses and mixing angles. Mild hierarchy in the 5D Yukawa matrix of O(25) in our numerical example is required to be consistent with two large and one small mixing angles. This tuning could be improved by having a more thorough search of the parameter space.