NEW CONSTRAINTS ON SUPERGRAVITY MODELS FROM B-]S-GAMMA

We perform a detailed study of the constraints from b→sγ on a large class of supergravity models, including generic four-parameter supergravity models, the minimal SU(5) supergravity model, and SU(5)×U(1) supergravity. For each point in the parameter spaces of these models we obtain a range of B(b→sγ) values which should conservatively account for the unknown next-to-leading-order QCD corrections. We then classify these points into three categories: ''excluded'' points have ranges of B(b→sγ) which do not overlap with the experimentally allowed range, ''preferred'' points have B(b→sγ) ranges which overlap with the standard model prediction, and ''okay'' points are neither ''excluded'' nor ''preferred'' but may become ''excluded'' should new CLEO data be consistent with the standard model prediction. In all cases we observe a strong tendency for the ''preferred'' points towards one sign of the Higgs mixing parameter μ. For the opposite sign of μ there is an upper bound on tanβ: tan β>25 in general, and tan β>6 for the ''preferred'' points. We conclude that new CLEO data will provide a decisive test of supergravity models. © 1995 The American Physical Society.