Search for Higgs Boson and Other Massive States Decaying into                  
Two Photons in e+e- Collisions at 189 GeV                                      
  
A search is described for the generic process                                  
e+e- -> XY, where X is a neutral heavy scalar boson decaying into a pair of    
photons, and Y is a neutral heavy boson (scalar or vector) decaying into       
a fermion pair. The search is motivated mainly by the cases where              
either X, or both X and Y, are Higgs bosons.                                   
In particular, we investigate the case where X is the Standard Model Higgs     
boson and Y the Z0 boson. Other models with enhanced Higgs boson decay         
couplings to photon pairs are also considered.                                 
The present search combines the data set collected by the OPAL collaboration   
at 189 GeV collider energy, having an integrated luminosity of 182.6 pb^-1,    
with data samples collected at lower energies.                                 
The search results have been used to put                                       
95 % confidence level bounds, as functions of the mass MX, on the product      
of the cross-section and the relevant branching ratios, both in a model        
independent manner and for the particular models considered.                   
  
 Parallel session :11                  
 Plenary  session :7a