G. Abbiendi et al., Search for Higgs bosons and other massive states decaying into two photonsin e(+)e(-) collisions at 189 GeV, PHYS LETT B, 464(3-4), 1999, pp. 311-322
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 ne
utral heavy boson (scalar or vector) decaying into a fermion pair. The sear
ch is motivated mainly by the cases where either X, or both X and Y, are Hi
ggs bosons. In particular, we investigate the case where X is the Standard
Model Higgs boson and Y the Z(0) boson. Other models with enhanced Higgs bo
son decay couplings to photon pairs are also considered. The present search
combines the data set collected by the OPAL collaboration at 189 GeV colli
der energy, having an integrated luminosity of 182.6 pb(-1), with data samp
les collected at lower energies. The search results have been used to put 9
5% confidence level bounds, as functions of the mass M-X, on the product of
the cross-section and the relevant branching ratios, both in a model indep
endent manner and for the particular models considered. (C) 1999 Elsevier S
cience B.V. All rights reserved.