Type: Article
Publication Date: 2005-01-26
Citations: 18
DOI: https://doi.org/10.1103/physrevd.71.014031
We study the threshold enhancement effects of baryon--antibaryon systems in $J/\ensuremath{\psi}$ decays at BES using parity $P$, charge conjugation $C$, and flavor $\mathrm{S}\mathrm{U}(3)$ symmetries. The $P$ and $C$ symmetries restrict the $p\overline{p}$ in $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{p}$ to be in a state with $C=+1$, while the $p\overline{p}$ in $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}p\overline{p}$ to be with $C=\ensuremath{-}1$. Combining the $C$ and $P$ symmetries with flavor $\mathrm{S}\mathrm{U}(3)$ symmetry, i.e., the CPS symmetry, we find that the $\ensuremath{\Lambda}\overline{p}$ system cannot be in ${0}^{+}$ and ${0}^{\ensuremath{-}}$ states in $J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\Lambda}\overline{p}$. We provide a consistent explanation of observation and nonobservation of near threshold enhancements in $J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\Lambda}\overline{p}$ and $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}p\overline{p}$, respectively. We also find that near baryon pair threshold enhancement can happen in several channels for $J/\ensuremath{\psi}$ decays and can be several times larger than that observed in $J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\Lambda}\overline{p}$ in some channels.