Light scalar mesons in photon—photon collisions
S.L. Sobolev Institute for Mathematics, Siberian Branch of the Russian Academy of Sciences, prosp. akad. Koptyuga 4, Novosibirsk, 630090, Russian Federation
Discovered more than forty years ago and from the very start a stumbling block for the naive quark—antiquark model, light scalar mesons are virtually universally believed to be nontrivial in nature today. A major contribution to understanding the nature of light scalar mesons has come from the physics of photon—photon collisions, a field which has recently entered the era of high-precision statistics. In this paper, conclusions from current experimental data concerning the mechanisms of the two-photon creation of light scalar mesons are reviewed.