Branching Ratios of J/ψ→π⁰3(π⁺π^-)

The decay mode of J/ψ→π⁰3(π⁺π^-) was studied very little before. There are no informations except branching ratios for this channel in PDG book which based on less than 0.2 × 10⁶ J/ψ events of MARK I. Now, BES I has a data sample of 7.8 × 10⁶ J/ψ events, we can make more accurate results than MARK I. Total of 3290 ± 43 J/ψ→π⁰3(π⁺π^-) events including 1275 ± 86 J/ψ→πω2(π⁺π^-) events are selected. J/ψ→π⁰3(π⁺π^-) and J/ψ→ω2(π⁺π^-) events have been generated with MC simulition for calculating events selection efficiency. BES I result is: Br (J/ψ→π⁰3(π⁺π^-)) = (2.52 ± 0.06 ± 0.43)% and Br(J/ψ→ω2(π⁺π^-)) = (1.31 ± 0.09 ± 0.21)%. Meanwhile, we studied the invariant mass of 4π and ωππ to find interesting signals. It seems that there is a peak at about 1.74GeV in the invarianat mass spectrum of 4π, and a enhancement was also found at about 1.9GeV in the invariant mass spectrum of ωππ. It is not clear whether they are from resonances or background. Therefore, more work in detail is still going on.