Models with higher weak-isospin Higgs multiplets

TL;DR

This paper explores extended Higgs sectors with higher weak-isospin multiplets to explain potential deviations in Higgs couplings, providing a comprehensive analysis of possible models consistent with current experimental data.

Contribution

It systematically classifies all viable two-multplet Higgs extensions that can modify Higgs couplings while maintaining electroweak precision constraints.

Findings

Current Higgs coupling measurements can be explained by models with complex and real triplet Higgs fields.

Derived general formulas for coupling modifiers in models with multiple exotic Higgs multiplets.

Identified minimal models compatible with observed deviations in Higgs couplings.

Abstract

In order for scale factors $\kappa_{V}^{}~(V=W,Z)$ of the 125-GeV Higgs boson couplings to have the possibilities of being greater than unity and $\kappa_{W}^{} \neq \kappa_{Z}^{}$ while keeping the electroweak $\rho$ parameter unity at tree level, the Higgs sector must be extended with at least two exotic $SU(2)_L$ multiplets in addition to the doublet Higgs field in the Standard Model. By the requirements of perturbative unitarity, no Landau pole in gauge couplings, and no accidental global $U(1)$ symmetry, we exhaust all the possible combinations of two exotic Higgs fields and derive general formulas for $\kappa_{V}^{}$. We find that the current central values $\kappa_W^{}=1.12$ and $\kappa_Z = 0.99$ reported by CMS can be accommodated in the model with a complex and a real Higgs triplets as the simplest example.