Measurement of two-photon decay width of χc2(1P) in γγ → χc2(1P) → J/ψγ at Belle

A bstract We report the measurement of two-photon decay width χ c 2 (1 P ) in processes at Belle experiment. analyze process γγ → J/ψγ , J/ψ ℓ + − ( = e or μ using a data sample 971 fb 1 collected with detector KEKB collider. In this analysis, product and branching fraction is determined to be $$ {\Gamma}_{\gamma \gamma}\left({\chi}_{c2}(1P)\right)\mathcal{B}\left({\chi}_{c2}(1P)\to J/\psi \gamma \right)\mathcal{B}\left(J/\psi \to {\ell}^{+}{\ell}^{-}\right)=14.8\pm 0.3\left(\textrm{stat}.\right)\pm 0.7\left(\textrm{syst}.\right) Γ γγ χ c 2 1 P B → J / ψγ ψ ℓ + − = 14.8 ± 0.3 stat . 0.7 syst eV, which corresponds Γ )) 653 ± 13(stat.) 31(syst.) 17(B.R.) where third uncertainty from \mathcal{B} ).