COMPARATIVE-ANALYSIS OF 3 METHODS TO EVALUATE VACUUM-POLARIZATION FUNCTIONS

The O(alphaalpha(s) contributions to the H0 --> l+ 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 w ith 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 addition al support to recent evaluations of the threshold contributions to bas ic corrections of the electroweak theory, as such analyses are based o n the same dispersion relations.