Measurements Of Some Baryonic Decays Of Charmonia

With 58 million J/φand 14 millionφ(2S) events collected with the BESâ…¡detector at the BEPC, branching fractions or upper limits on branching fractions for the baryonic decays J/φ→Λ(?)Ï€⁰, J/φ→Λ(?)η,φ(2S)→Λ(?)Ï€⁰,φ(2S)→Λ(?)η, J/φ→∑⁺(?) and J/φ→Ξ⁰(?) are measured.In the analysis of J/φ→Λ(?)Ï€⁰, we found that the observedÏ€⁰ was seriously contaminated by the backgrounds J/φ→∑⁰Ï€⁰(?) + c.c. and J/φ→∑⁺Ï€^-(?) + c.c. Considering the contributions of these crucial backgrounds, we found that the branching fraction of J/φdecaying toΛ(?)Ï€⁰ is smaller than previous measurements. In contrast to the large value ((2.2±0.6)×10^-4) of branching fraction of J/φ→Λ(?)Ï€⁰ in PDG 2006, we determined, at the 90% confidence level,In the measurement J/φ→Λ(?)η, we optimized the event selections, and observed the signal ofηin theγγinvariant mass for the first time. The statistical significance is 4.8σ, and the branching fraction is measured to be,where the first error is statistical and the second systematic. Comparing the distinct values of the branching fraction of J/φ→Λ(?)Ï€⁰ and J/φ→Λ(?)η, we found that our results are in accord with the theoretical predictions of the relative large branching fraction of strong interaction. Therefore, our results indicate that there is no abnormal physics in J/φ→Λ(?)Ï€⁰, and J/φ→Λ(?)ηdecays.Similarly, we also analyzedφ(2S) decaying intoΛ(?)Ï€⁰, andΛ(?)η. No signals were found inφ(2S) decays, and the upper limits at the 90% confidence level are determined to be,Furthermore, we observed the baryon pair processes J/φ→∑⁺(?) and J/φ→Ξ⁰(?) for the first time, and measured the branching fractions to be,where the first error is statistical and the second systematic. These results are consistent with the branching fractions of their isospin partners J/φ→∑⁰(?) and J/φ→Ξ^-(?) with expectations of isospin symmetry. Using the recent branching fractions ofφ(2S)→∑⁺(?) andφ(2S)→Ξ⁰(?) measured by CLEO collaboration, we found that the ratio of the branching fraction ofφ(2S) and J/φdecaying to∑⁺(?) andΞ⁰(?) agree with the so called " 12% rule" predicted by perturbative QCD within1σ.