Radiative decays of phi-meson about nature of light scalar resonances

摘要

We show on gauge invariance grounds that the fine threshold phenomenon is discovered in the radiative decays phi --> gammaa(0) --> gammapi(0)eta and phi --> gammaf(0) --> gammapi(0)pi(0). This enables to conclude that production of the lightest scalar mesons a(0)(980) and f(0)(980) in these decays is caused by the four-quark transitions, resulting in strong restrictions on the large N-C expansions of the decay amplitudes. The analysis shows that these constraints give new evidences in favor of the four-quark nature of a(0)(980) and f(0)(980) mesons. (C) 2003 Elsevier B.V. All fights reserved. [References: 55]