TOP QUARK EFFECTS ON THE SCALAR SECTOR OF THE MINIMAL STANDARD MODEL

Abstract

We study effects of the heavy top quark (mt≈180 GeV) on the scalar sector of the minimal standard model. We construct the effective potential for the scalar doublet, by first taking into account the leading contributions of the top quark loops. Minimizing this potential gives us a condition analogous to the leading Nc gap equation of the standard [Formula: see text] condensation model (top-mode standard model). This essentially nonperturbative condition leads to a low ultraviolet cutoff [Formula: see text] in the case when the bare mass μ of the scalar doublet in the tree-level potential satisfies [Formula: see text] and the scalar doublet there is self-interacting (λ>0). We demand that the scalar self-interaction behaves perturbatively — in the sense that its one-loop contributions influence the effec-tive potential distinctly less than those of the Yukawa coupling of the heavy top quark. When we subsequently include the one-loop contributions of the scalar and the gauge bosonic sectors in a perturbative manner, the results change numerically, but the cutoff A remains [Formula: see text]. The resulting Higgs mass MH is then in the range 150–250 GeV. Furthermore, the results of the paper survive even in the case when the square of the bare mass μ2 is positive, as long as [Formula: see text], where λ/4! is the usual bare coupling parameter of the quartic self-interaction of the scalars and ν is the vacuum expectation value [Formula: see text].