Limits on Higgs bosons, scalar-quarkonia, and eta b's from radiative upsilon decays.

We have searched for monochromatic photon signals in the reaction \ensuremath{\Upsilon}(9460)\ensuremath{\rightarrow}X+\ensuremath{\gamma} in a sample of 420 000 \ensuremath{\Upsilon} decays observed in the CUSB detector. From the absence of signal we obtain upper limits for Higgs-boson production in \ensuremath{\Upsilon} decay which approach the minimal-standard-model expectations, including QCD radiative corrections, for low Higgs-boson masses. For two Higgs-boson models we obtain bounds on the ratio of the vacuum expectation values of the two neutral Higgs fields as a function of the Higgs-boson mass. We do not confirm the \ensuremath{\zeta}(8.3) and find no evidence for a nearby bound scalar-quark--anti-scalar-quark state. We obtain a lower bound for the ${\ensuremath{\eta}}_{b}$ mass using potential-model predictions.