Evidence for an interference effect between ω and φ resonances in π+π-πo production by e+e- annihilation
The cross section e+e--->π+π-πo has been measured in the φ energy region and at three other energies (915, 990, 1076 MeV) chosen outside the ω and φ resonances. In the same experiment the energy position and the width of the φ resonance have been determined from the φ-->KSoKLo channel. It is found that the magnitude and energy dependence of the experimental cross section are well described by coherent production of ω and φ in the whole energy range 770 to 1076 MeV. Our data clearly show an interference effect which corresponds to an opposite sign between the two products gγωgω-->3π and gγφgφ-->3π of the coupling constants.