Relativistic effects in radiative transitions of charmonia

In the framework of a relativistic quark model constructed in an infinite momentum frame, corrections of the order of v2c2 are obtained in the formulas which express amplitudes of the transitions ψ(ψ′) → ηc(ηc′)γ, χJ → ψγ, ψ′ → χJγ, hc → ηcγ, ηc′ → hcγ through overlap integrals ∫ φ∗f(q)φi(q)dq, ∫ φ∗f(r)rφi(r)dr. These corrections lead to a considerable suppression of Γ(ψ → ηcγ); however, they are insufficient to remove the existing disagreement of quark model predictions with experiment. Taking into account the relativistic corrections, the ratios of overlap integrals for χ0 → ψγ, χ2 → ψγ and ψ′ → χ0γ, ψ′ → χ2γ transitions are extracted from experiment; the obtained results are compared with quark model predictions.