Comparative analysis of three methods to evaluate vacuum-polarization functions

The O(ααS) contributions to the H0åℓ+ℓ− decay width are studied on the basis of two different classes of dispersion relations for the vacuum-polarization functions of vector bosons, and compared with the results obtained using dimensional regularization. It is found that the latter agrees with one of the two approaches, thus providing explicit support to this formulation. This result also gives additional support to recent evaluations of the threshold contributions to basic corrections of the electroweak theory, as such analyses are based on the same dispersion relations