Charmed quark component of the photon wave function

AbstractWe determine the $$c\bar c$$ component of the photon wave function on the basis of (i) the data on the transitions e+e− → J/ψ(3096), ψ(3686), ψ(4040), ψ(4415), (ii) partial widths of the two-photon decays ηc0(2979), χc0(3415), χc2(3556) → γγ, and (iii) wave functions of the charmonium states obtained by solving the Bethe-Salpeter equation for the $$c\bar c$$ system. Using the obtained $$c\bar c$$ component of the photon wave function, we calculate the γγ-decay partial widths for radial excitation of the 2S state, ηc0(3594) → γγ, and 2P states χc0(3849), χc2(3950) → γγ.