Electroweak-Higgs unification in the two Higgs doublet model: masses and couplings of the neutral and charged Higgs bosons

Abstract

We obtain the mass spectrum and the Higgs self-couplings of the two Higgs doublet model (THDM) in an alternative unification scenario where the parameters of the Higgs potential $\lambda_i$ ($i=1,2,3,4,5$) are determined by imposing their unification on the electroweak gauge couplings. An attractive feature of this scenario is the possibility of determining the Higgs boson masses by evolving the $\lambda_i$ from the electroweak-Higgs unification scale $M_{GH}$ down to the electroweak scale. The unification condition for the gauge ($g_1,g_2$) and Higgs couplings is written as $g_1=g_2=f(\lambda_i)$, where $g_1=k_Y^{1/2} g_Y$, and $k_Y$ isthe normalization constant. Two variants for the unification condition are discussed: Scenario I is defined through the linear relation: $g_1=g_2=k_H(i)\lambda_i(M_{GH})$, while Scenario II assumes a quadratic relation $g^2_1=g^2_2=k_H(i)\lambda_i(M_{GH})$. In Scenario I, by setting ad hoc $-k_H(5)=\frac{1}{2} k_H(4)=\frac{3}{2} k_H(3)=k_H(2)=k_H(1) =1$, taking $\tan\beta=1$ and using the standard normalization ($k_Y=5/3$), we obtain the following spectrum for the Higgs boson masses: $m_{h^0} = 109.1$ GeV, $m_{H^0} = 123.2$ GeV, $m_{A^0} = 115.5$ GeV, and $m_{H^{\pm}} = 80.3$ GeV, with similar results for other normalizations such as $k_Y=3/2$ and $k_Y=7/4$.