Production of mesons in photon-photon collisions at LEP

Abstract We present an observation at LEP of the production of χc2 mesons in the collisions of two quasi-real photons using the OPAL detector. The χc2 mesons are reconstructed in the decay channel χ c2 →J/ψ γ→l + l − γ (with l = e,μ) using all data taken at e+e− centre-of-mass energies of 91 and 183 GeV, corresponding to integrated luminosities of 167 and 55 pb−1 respectively. The two-photon width of the χc2 is determined to be Γ(χc2→γγ)=1.76±0.47±0.37±0.15 keV, where the first error is statistical, the second is systematic and the third comes from branching ratio uncertainties.

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