K. Ackerstaff et al., SEARCH FOR A MASSIVE DI-PHOTON RESONANCE AT ROOT-S=91-172 GEV, EUROPEAN PHYSICAL JOURNAL C-PARTICLES AND FIELDS, 1(1-2), 1998, pp. 31-43
A search for the resonant production of high mass photon pairs associa
ted with a leptonic or hadronic system has been performed using a tota
l data sample of 25.7 pb(-1) taken a! 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 Model
processes. The observed candidates are combined with search results fr
om root s approximate to M-z to place limits on B(H-0 --> gamma gamma)
within the Standard Model for Higgs boson masses up to 77 GeV, and on
the production cross section of any scaler resonance decaying into di
-photons. Upper limits on B(H-0 --> gamma gamma) x sigma(e(+)e(-)-->H2
O) of 290 - 830 fb are obtained over 40 < M-H < 160 GeV. Higgs scalars
which couple only to gauge bosons with Standard Model strength are ru
led out lip to a mass of 76.5 GeV at the 95% confidence level.