UPDATED BOUNDS ON HIGGS TRIPLET VACUUM EXPECTATION VALUES AND THE TREE-LEVEL ρ PARAMETER FROM RADIATIVE CORRECTIONS

Abstract

We obtain 95% C. L. upper limits on the ratio of triplet to doublet vacuum expectation values in two extended electroweak models from radiative corrections. We use as input data from LEP, the Tevatron, the CERN [Formula: see text] colliders, and various low-energy experiments such as atomic parity-violation and deep inelastic scattering. The analysis includes the incorporation of leading two-loop electroweak contributions to ∆r and ρ arising from heavy top quarks and Higgs bosons, the Consoli–Hollik–Jegerlehner resummation technique, and QCD corrections to the hadronic partial widths of the Z using the new value for the (αs/π)3 coefficient. Our limits are found to be only mildly sensitive to the top quark and Higgs boson masses and somewhat stronger than those obtained previously. Our results are then generalized to bounds on the allowed value of the tree-level ρ parameter.