How reliably can the Higgs-Boson Mass be predicted from Electroweak Precision Data?
نویسندگان
چکیده
From the LEP precision data, upon excluding the observables Rb, Rc in a combined fit of the top-quark mass, mt, and the Higgs-boson mass, MH, within the Standard Model, we find the weak 1σ bound of 40GeV < ∼ MH < ∼ 1TeV. Stronger upper bounds on MH, sometimes presented in the literature, rely heavily on the inclusion of Rb in the data sample. Upon including Rb, the quality of the fit drastically decreases, and mt comes out significantly below the experimental value of mt = 180± 12GeV, thus implying that the stronger bounds are not reliable. Moreover, the stronger bounds on MH are lost if the deviation between theory and experiment in Rb is ascribed to contributions of new physics. Replacing s̄ W (LEP) by s̄ W (SLD) in the data sample leads to the tight bound of MH < ∼ 35GeV at the 1σ level, which is in conflict, however, with MH > ∼ 65.2GeV from direct searches.
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