Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons 0 , , and Ј. From our measurements we have obtained the form factors associated with the electromagnetic transitions ␥*␥→meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV 2 for 0 , , and Ј, respectively, and have made comparisons to various theoretical predictions. ͓S0556-2821͑98͒01001-7͔

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We report on the observation of the eta(')(c)(2(1)S0), the radial excitation of the eta(c)(1(1)S0) ground state of charmonium, in the two-photon fusion reaction gammagamma-->eta(')(c)-->K(0)(S)K+/-pi(-/+) in 13.6 fb(-1) of CLEO II/II.V data and 13.1 fb(-1) of CLEO III data. We obtain M(eta(')(c))=3642.9+/-3.1(stat)+/-1.5(syst) MeV and M(eta(c))=2981.8+/-1.3(stat)+/-1.5(syst) MeV. The corresponding values of hyperfine splittings between 1S0 and 3S1 states are DeltaM(hf)(1S)=115.1+/-2.0 MeV and DeltaM(hf)(2S)=43.1+/-3.4 MeV. Assuming that the eta(c) and eta(')(c) have equal branching fractions to K(S)Kpi, we obtain Gamma(gammagamma)(eta(')(c))=1.3+/-0.6 keV.

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