Radiative corrections of heavy scalar decays to gauge bosons in the singlet extension of the Standard Model

Assuming the existence of a new real scalar singlet s(0) coupled to the Standard Model via a scalar quartic portal interaction, we compute the radiative corrections to the decay rates of the heavy scalar mass eigenstate to a couple of gauge bosons ZZ and W+ W-(gamma), showing that they can give a contribution as large as (5%) and O(7%), respectively. We also explicitly analyze in detail their dependence on the heavy mass m(S) and on the scalar mixing angle a, finding that, especially in the large-mass region, these depend on the sign and the assumed value of sin alpha.