Flavor physics in the multi-Higgs doublet models induced by the left-right symmetry

TL;DR

This paper explores flavor physics in multi-Higgs doublet models derived from left-right symmetric extensions of the Standard Model, analyzing flavor-changing effects and predictions for rare processes like mu to 3e.

Contribution

It introduces a detailed phenomenological analysis of flavor-changing interactions in supersymmetric left-right symmetric models with multiple Higgs doublets, emphasizing the impact of neutrino mass hierarchy.

Findings

Heavy Higgs doublets induce sizable flavor-changing couplings.

Predictions for mu to 3e decay could be tested in future experiments.

Flavor observables are correlated with neutrino mass ordering.

Abstract

In this paper, we discuss the multi-Higgs doublet models, that could be effectively induced by the extended Standard Model (SM). In particular, we focus on the phenomenology in the supersymmetric model with left-right (LR) symmetry, where the down-type and the up-type Yukawa couplings are unified and the Yukawa coupling matrices are expected to be hermitian. In this model, several Higgs doublets are introduced to realize the realistic fermion mass matrices, and the heavy Higgs doublets have flavor changing couplings with quarks and leptons. The LR symmetry is assumed to break down at high energy to realize the Type-I seesaw mechanism. The supersymmetry breaking scale is expected to be around 100 TeV to achieve the 125 GeV Higgs. In such a setup, the flavor-dependent interaction of the Higgs fields becomes sizable, so that we especially discuss the flavor physics induced by the heavy Higgs fields in our work. Our prediction depends on the structure of neutrinos, e.g., the neutrino mass ordering. We demonstrate how the flavor structure of the SM affects the flavor violating couplings. In our analysis, we mainly focus on the four-fermi interaction induced by the scalar exchanging, and we propose a simple parameterization for the coefficients. Then, we find the correlations among the flavor observables and, for instance, see that our prediction for the $\mu \to 3 e$ process could be covered by the future experiment, in one case where the neutrino mass hierarchy is normal.