Models with higher weak-isospin Higgs multiplets

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 ${\kappa }_W^{}\ne {\kappa }_Z^{}$ 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.

Comments: 4 pages, 2 figures