b→sγ AND ε1 CONSTRAINTS ON SUPERGRAVITY MODELS

In the light of the top quark discovered very recently by CDF, we investigate the possibility of narrowing down the allowed top quark masses by combining for the first time only two strongest constraints present in the no-scale SU(5)×U(1) supergravity model, namely, the ones from the flavor-changing radiative decay b→sγ and the precision measurements at LEP in the form of e1. It turns out that even without including the most devastating constraint from measurement at LEP in the form of Rb directly or eb indirectly, the combined constraint from b→sγ and e1 alone in fact excludes mt(mt)≳180 GeV altogether in the no-scale model, providing a constraint on mt near the upper end of the CDF values. The resulting upper bound on mt is stronger and 5 GeV lower than the one from combining e1 and eb constraints and also combining b→sγ and eb constraints in the previous analysis.