Quark-antiquark states and their radiative transitions in terms of the spectral integral equation: Light mesons

We continue the investigation of mesons in terms of the spectral integral equation initiated before for the bb-bar and cc-bar systems; we consider the light-quark (u, d, s) mesons with masses M ≤ 3 GeV. The calculations have been performed for the mesons lying on linear trajectories in the (n, M2) planes, where n is the radial quantum number. Our consideration relates to the qq-bar states with one component in the flavor space, with the quark and antiquark masses equal to each other, such as π(0-+), ρ(1--), ω(1--), φ(1--), a0(0++), a1(1++), a2(2++), b1(1+-), f2(2++), π2(2-+), ρ3(3--), ω3(3--), φ3(3--), π4(4-+) at n ≤ 6. We obtained the wave functions and mass values of mesons lying on these trajectories. The corresponding trajectories are linear, in agreement with data. We have calculated the two-photon decays π, a0(980), a2(1320), f2(1285), f2(1525) and radiative transitions ρ, ω → γπ, which agree qualitatively with the experiment. On this basis, we extract the singular part of the interaction amplitude, which corresponds to the so-called 'confinement interaction.' The description of the data requires the presence of the strong t-channel singularities for both scalar and vector exchanges