CONSTRAINTS ON NEW PHYSICS IN THE ELECTROWEAK BOSONIC SECTOR FROM CURRENT DATA AND FUTURE EXPERIMENTS

Extensions of the Standard Model which involve a new scale, Lambda, ma y, for energies sufficiently small compared to this new scale, be expr essed in terms of operators with energy dimension greater than four. T he coefficients of just four SU(2)xU(1) -gauge-invariant energy-dimens ion-six operators are sufficient to parameterize the contributions of new physics in the electroweak bosonic sector to electroweak precision measurements. In this letter we update constraints on the coefficient s of these four operators due to recent precision measurements of elec troweak observables. We further demonstrate how such constraints may b e improved by experiments at TRISTAN, LEP2 and at a future linear e(+) e(-) collider. The relationship of these operators to the oblique para meters S, T and U is examined. Two of the operators contribute to a no n-standard running of the electroweak charge form-factors alpha(q(2)), s(-2) (q(2)), g(z)(-2) (q(2)) and g(w)(-2) (q(2)); in the special case where the coefficients of these two vanish the operator analysis redu ces to an analysis in terms of S, T and U with U = 0.