RARE Φ DECAYS AND EXOTIC HADRONS

Abstract

Exotic hadrons re those whose structure differs from the usual q1q2 structure for mesons and q1q2q3 for baryons. Their exotic nature could reveal itself in unusual properties, for example, suppressed or enhanced decays, too wide or too narrow decay widths, or quantum numbers forbidden in the conventional structure. Up to now, among the huge variety of hadrons, about 10 candidates were found which look like exotic states. In the scalar meson sector, the lowest lying states f0(980) and a0(980) are candidates for exotic hadrons. The main motivations for this are their suppressed production in J/Ψ decays, their low widths to γγ, and their low masses. More generally, one might describe the f0 and a0 mesons with one of three models [1]—a conventional qq model, a molecular model (KK), and a 4-quark model (qqqq). The qq model is only barely consistent with experimental data. It was proposed more than ten years ago that the measurement of the radiative decaysφ → f0γ,φ → a0γ was a sensitive test that could distinguish thesemodels [2]. These decays were studied recently in the reactions: