Constraint on the top-quark mass from the Nambu-Goldstone hypothesis on Higgs supermultiplets

A constraint on the top-quark mass is obtained in a supergravity model based on the Nambu-Goldstone hypothesis for the Higgs supermultiplets. Imposing that the Higgs effective potential with the one-loop correction from the top-quark supermultiplet has a correct electroweak symmetry-breaking minimum, the top-quark mass is calculated in a wide range of free parameters. The obtained top-quark mass is bounded above as $m_{\mathrm{top}}\lesssim 140$ GeV. The upper bound for the lightest neutral Higgs-boson mass is also derived as Å 110 GeV.