Measurement of Χc2 production in two-photon collisions

Abstract The production of the χ c 2 charmonium state in two-photon collisions has been measured with the Belle detector at the KEKB e + e − collider. A clear signal for χ c 2 → γJ / ψ , J / ψ → l + l − is observed in a 32.6 fb −1 data sample accumulated at center-of-mass energies near 10.6 GeV, and the product of its two-photon decay width and branching fraction is determined to be Γ γ γ ( χ c 2 ) B ( χ c 2 → γ J / ψ ) B ( J / ψ → l + l − ) = 13.5 ± 1.3 ( stat . ) ± 1.1 ( syst . ) eV .