The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ → γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function...The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ → γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G（p） with the form of 285500/（m 2 π ＋ p 2 ） should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ →π 0 pp process is also discussed.展开更多
基金Supported by National Natural Science Foundation of China (10675022, 10975018, 10975038, 11035006, 11165005, 11175020)Fundamental Research Funds for the Central UniversitiesKey-project by the Chinese Academy of Sciences (KJCX3-SYW-N2)
文摘The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ → γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G（p） with the form of 285500/（m 2 π ＋ p 2 ） should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ →π 0 pp process is also discussed.
