TOP AND HIGGS HUNTING VIA Mw AND Γz

Abstract

Virtual top and Higgs effects are studied through the electroweak radiative corrections to the W boson mass, MW, and the total decay-width of the Z boson, ΓZ, by using the data [Formula: see text], [Formula: see text] and [Formula: see text]. Carrying out the χ2 fit in the framework of the standard electroweak theory, constraints are derived on the top-quark mass, mt, and the Higgs–boson mass, mϕ, which are almost free from the complicated hadron physics like parton model calculations. For example, [Formula: see text] for mϕ = 100 GeV (at 1σ level) while mϕ ≲ 680 GeV if mt ≤ 110 GeV and mϕ ≳ 280 GeV if mt ≥ 190 GeV . It is also studied how precise measurements of MW at LEP II improve these constraints.