Constraining the CP4-invariant three-Higgs-doublet model via top quark decays

TL;DR

This paper investigates the CP4-invariant three-Higgs-doublet model, focusing on top quark decays and flavor constraints, and identifies viable models with light Higgs bosons that can be tested at the LHC.

Contribution

It narrows down the viable CP4-invariant Yukawa sectors using a novel scanning procedure, linking flavor physics constraints to top quark decay phenomenology.

Findings

Identified a unique Yukawa sector compatible with meson oscillation and top decay constraints.

Presented benchmark models with light neutral or charged Higgs bosons lighter than the top quark.

Proposed experimental tests at the LHC and flavor physics experiments.

Abstract

CP4 3HDM is a peculiar three-Higgs-doublet model in which a single symmetry leads to tight constraints on the scalar and Yukawa sectors. In this models, tree-level flavor-changing neutral couplings are unavoidable; however, as previously shown, their contributions to neutral meson oscillations can be suppressed. Here, we explore the remaining quark flavor violating effects, which give rise to the top quark decays to light scalars, including the 125 GeV Higgs boson $h_{SM}$, as well as the magnitude of the $h_{SM} t\bar t$ coupling. Utilizing the recently developed scanning procedure, in which observables are used as input, we narrow down the viable options to a unique CP4-invariant Yukawa sector capable of satisfying all meson oscillation and top quark constraints. We present benchmark models that feature neutral or charged Higgs bosons lighter than the top quark, and we look forward to testing them further at the LHC and through flavor physics observables.