Outline: 1. Introduction, 2. Confinement, chiral dynamics and light scalar mesons, 3. Chiral shielding of the σ(600), chiral constraints (the CGL band), the σ(600) and the f0(980) in ππ → ππ, ππ → K ¯ K, φ → γπ 0 π 0 , 4. The φ meson radiative decays on light scalar resonances, 5. Light scalars in γγ collisions. Evidence for four-quark components of light… (More)
The light scalar mesons, discovered forty years ago, became a challenge for the naive quark-antiquark model from the outset. At present the nontrivial nature of these states is no longer denied practically anybody. We review a substantial contribution of the two-photon physics to understanding the nature of the light scalar mesons and new results for their… (More)
We consider the lightest scalar meson in the frame of the SU(L)2 x SU(R)2 linear sigma model, keeping in mind that this model could be the low energy realization of two-flavor QCD. We show that the sigma field is described by its four-quark component at least in the sigma resonance energy (virtuality) region and the sigma-->gammagamma decay is the… (More)
The K+ and K0 meson mass difference induces the mixing of the a(0)(0)(980) and f(0)(980) resonances, the amplitude of which, between the K+K- and K0(-)K(0) thresholds, is large in magnitude, of the order of m(K)m(2)(K0)sqrt[-m(2)(K+)] approximately sqrt[alpha] m(2)(K), and possesses the phase sharply varying by about 90 degrees. We suggest performing the… (More)
We would like to point to the strong violation of the putative factorized Pomeron exchange model in the reactions γγ → V V ′ in the high energy region where this model works fairly well in all other cases.