Search for a narrow resonance in Z0 decays into hadrons and isolated photons

A search for the hadronic decay of a hypothetical resonance S0 in the process e+e-→γ+hadrons at Z0 energies is reported. Particular care is taken to optimise the sensitivity to a scalar resonance decaying into bottom quarks, as expected for Higgs production, e+e-→Z0→H0γ with H0→b anti b, in the Standard Model or some of its extensions. No evidence for such a resonance is observed in a sample of about 5 million produced Z0's. The results are interpreted in terms of models of non-standard Higgs production. An update of a search for a resonance produced in association with hadrons and the subsequent resonance decay into two photons is also presented. (orig.)