Nature of the a0(980) meson in the light of photon-photon collisions

New high-statistics Belle data on the reaction γγ→π0η are analyzed to clarify the two-photon production mechanisms and the nature of the a0(980) meson. The obtained solution for the amplitude γγ→π0η is consistent with the chiral theory expectation for the πη scattering length, with the strong coupling of the a0(980) to the πη, KK, and πη' channels, and with a key role of the rescattering mechanisms a0(980)→(KK+π0η+π0η')→γγ in the a0(980)→γγ decay. Such a picture argues in favor of the q2q2 nature of the a0(980) meson and is in agreement with the properties of its partners, the σ0(600) and f0(980) mesons, in particular, with those that manifest themselves in γγ→ππ. An important role of the vector meson exchanges in the formation of the nonresonant background in γγ→π0η is also revealed. The preliminary information on the reaction π0η→π0η is obtained.