Two-photon decay of the pseudoscalar meson in the relativistic quark model

In the relativistic quark model, based on the point form of Poincaré-invariant quantum mechanics, an integral representation of the form-factor of the pseudoscalar P0(π0,η,η′) meson of  P0 (qq̅)→γγ decay is obtained taking into account the anomalous magnetic moments of u-, d- and s-quarks. IIn the developed formalism the values of the constituent quark masses and the parameters of the wave functions are calculated using the lepton decay  P±(qQ̅ ) → ℓ±νℓ± constant fP± and the pseudoscalar density constant gP±. It is shown that taking into account the gluonium component in η/η′-mesons and using the structure functions of light sector quarks lead to the behavior of the form factors of pseudoscalar π0-, η-, η′-mesons in the area of a small transferred momentum to the lepton pair, which is consistent with the modern experimental data