Precision test of electroweak parameters and new physics

In certain classes of beyond-the-standard model heavy particles of mass M larger than the weak boson mass MW contribute to light particle processes through radiative corrections. We report our recent studies of the non-decoupling effects of heavy particles of this type in the gauge boson two- and three-point functions. We have obtained a few results: 1) The analysis of the symmetry properties of the S, T, U parameters of the two-point functions is useful in understanding the oblique corrections. 2) Comparison with the precision measurements of S and T gives a meaningful upper bound on the number of extra generations Neg. 3) Regarding the triple gauge-boson couplings, we have identified the four parameters which are sufficient to describe the non-decoupling effects of heavy particles in the γW+W- was Z0W+W- couplings. (author)