A GENERAL TREATMENT OF OBLIQUE PARAMETERS

A re-examination is made of one-loop oblique electroweak corrections. General definitions are given of the oblique parameters without refere nce to any q(2) expansion scheme. The old oblique parameters S, T and U are defined as differences of gauge boson Vacuum polarization Pi fun ctions and suffice for describing certain observable ratios on the Z p eak and the rho parameter at q(2) = 0. Regarding the new oblique param eters V, W and X, the first two are defined in terms of differences of Pi functions as well as the wave function renormalization of the corr esponding weak boson, and the third in terms of the difference of diff erences of two Pi functions for gamma - Z mixing. Explicit expressions for measurable quantities involving all six oblique parameters are gi ven and experimental bounds are obtained on the latter, some for the f irst time. A review of these constraints suggests that the linear appr oximation of Peskin and Takeuchi is robust.