On Stringy Origin of Minimal Flavor Violation

TL;DR

This paper explores how string theory's selection rules influence flavor and CP violation in the Standard Model, suggesting that Yukawa couplings derived from string theory underpin minimal flavor violation.

Contribution

It demonstrates that stringy selection rules naturally lead to minimal flavor violation by linking Yukawa couplings to flavor and CP dynamics in effective field theories.

Findings

Yukawa couplings act as spurions for flavor symmetries.

Stringy selection rules constrain fermion and scalar interactions.

Supports the hypothesis that minimal flavor violation arises from string theory.

Abstract

We study the minimal flavor violation in the context of string effective field theory. Stringy selection rules indicate that $n$-point couplings among fermionic zero-modes and lightest scalar modes in the string effective action are given by a product of Yukawa couplings which are regarded as spurion fields of stringy and geometrical symmetries. Hence, Yukawa couplings determine the dynamics of flavor and CP violations. This observation strongly supports the hypothesis of minimal flavor violation in the Standard Model effective field theory.