Hermitian Flavor Violation

TL;DR

This paper proposes a two Higgs doublet model with Hermitian Yukawa couplings that allows large first-generation quark interactions while avoiding flavor-changing neutral current constraints, potentially explaining Tevatron W+dijet excesses.

Contribution

It introduces a novel two Higgs doublet model with Hermitian Yukawa matrices, enabling large first-generation couplings and addressing flavor constraints and the strong CP problem.

Findings

Model can accommodate large first-generation quark couplings.

Potential explanation for Tevatron W+dijet excess.

Hermitian Yukawa matrices naturally relate to strong CP solutions.

Abstract

The fundamental constraint on two Higgs doublet models comes from the requirement of sufficiently suppressing flavor-changing neutral currents. There are various standard approaches for dealing with this problem, but they all tend to share a common feature; all of the Higgs doublets couple very weakly to the first generation quarks. Here we consider a simple two Higgs doublet model which is able to have large couplings to the first generation, while also being safe from flavor constraints. We assume only that there is an SU(3)_f flavor symmetry which is respected by the couplings of one of the Higgs doublets, and which is broken by Hermitian Yukawa couplings of the second doublet. As a result of the large permitted couplings to the first generation quarks, this scenario may be used to address the excess in W+dijet events recently observed by CDF at the Tevatron. Moreover, Hermitian Yukawa coupling matrices arise naturally in a broad class of solutions to the strong CP problem, providing a compelling context for the model.