A feasibility study has been carried out for high precision measurements of two-photon reactions leading to hadrons at the DAPHNE electron-positron collider. This new facility will operate at a CM energy of 1. 02 GeV and up to a maximum of 1. 5 GeV. It will have a luminosity of L⋍5x10³2 cm^-2 s^-1, 100 times larger than the present available e^+e^- colliders. DAPHNE offers an excellent opportunity to study γγ reactions at low energy with high statistics, using the KLOE detector equipped with electron tagging facilities as described in this report. Among the various topics that one may address in these studies, we concentrate on the following: (1) Precision measurements of the polarizabilities of charged and neutral pions via the two-photon reactions γγ->ππ. These will allow tests of chiral theories and chiral perturbation techniques, as well as other theoretical approaches. (2) Measurements for the first time of the azimuthal correlations of the γγ->ππ and other two-photon reactions. This provides new tests of the validity of chiral and other theories. (3) Formation of the C = +1 light pseudoscalar mesons, π⁰, η and η'. This allows the study of the qq ̅ and possibly gg inner structure of these mesons. For the π⁰ its measured radiative width will also improve the currently known life-time. (4) The possibility to realize a double tagging at DAPHNE will allow reliable measurements of the total γγ-> hadrons cross section below 1 GeV, which currently is vaguely known to be compared with several models. The physics program described above cannot be realized without tagging the two-photon reactions to suppress the background from e^+e^- annihilation channels and other sources.
G. et al. (Mon,) studied this question.
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