Implications ofb→sγDecay Measurements in Testing the Higgs Sector of the Minimum Supersymmetric Standard Model

The observation that the $b\to s\gamma$ decay rate is close to the standard model value implies a large mass for the charged Higgs boson in the minimum supersymmetric standard model (MSSM), which nearly closes the $t\to b{H}^{+}$ decay channel. For $m_t=150\mathrm{}$ GeV, the parameter region $m_A\lesssim 130$ GeV is excluded; this largely preempts searches at the CERN $e^{+}{e}^{-}$ collider LEP II and also partially excludes a region that would be inaccessible to MSSM Higgs boson searches at LEP II and at the Superconducting Super Collider and the CERN Large Hadron Collider.