Prescription for finite oblique parameters S and U in extensions of the SM with m W ≠ m Z  cos  θ W .

We consider extensions of the standard model (SM) with neutral scalars in multiplets of SU (2) larger than doublets. When those scalars acquire vacuum expectation values, the resulting masses of the gauge bosons W ± and Z 0 are not related by m W = m Z  cos  θ W . In those extensions of the SM the oblique parameters S and U, when computed at the one-loop level, turn out to be either gauge-dependent or divergent. We show that one may eliminate this problem by modifying the Feynman rules of the SM for some vertices containing the Higgs boson; the modifying factors are equal to 1 in the limit m W = m Z  cos  θ W . We give the result for S in a model with arbitrary numbers of scalar SU (2) triplets with weak hypercharges either 0 or 1. [ABSTRACT FROM AUTHOR]