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

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 (91, 92) and Higgs cou- plings is written as g1 = 92 = f (lambda(i)), where g(1) = k(Y)(1/2) gy, 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 (MGH), while Scenario 11 assumes a quadratic relation g(1)(2)= g(2)(2) = k(H) (i)lambda i (M-GH). In Scenario 1, by setting ad hoc -k(H) (5) (1)/(2)k(H) (4) = kH (3) = kH (2) = kH (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-HO = 123.2 GeV, m(A)0 = 115.5 GeV, and M-H +/- = 80.3 GeV, with similar results for other normalizations such as ky = 3/2 and ky = 7/4.