Search for a massive Di-photon resonance at ∝s = 91 – 172 GeV

A search for the resonant production of high mass photon pairs associated with a leptonic or hadronic system has been performed using a total data sample of 25.7 pb−1 taken at centre-of-mass energies between 130 GeV and 172 GeV with the OPAL detector at LEP. The observed number of events is consistent with the expected number from Standard Modelprocesses. The observed candidates are combined with search results from ∝s ≈ Mz to place limits onB(H0 → γγ within the Standard Modelfor Higgs boson masses up to 77 GeV, and on the production cross section of any scalar resonance decaying into di-photons. Upper limits onB(H0 →4 γγ x σ(e+e− → H°Z°) of 290 – 830 fb are obtained over 40 gauge bosonswith Standard Modelstrength are ruled out up to a mass of 76.5 GeV at the 95% confidence level.