The Light Baryonium Spectrum

We evaluate the light baryonium sepectrum, viz. the baryon-antibaryon states, in the framework of QCD sum rules. The non-perturbative contributions up to dimension 12 are taken into account. Numerical results indicate that there might exist 8 possible light baryonium states, i.e. $p$-$bar{p}$, $Lambda$-$bar{Lambda}$, $Sigma$-$bar{Sigma}$, and $Xi$-$bar{Xi}$ with quantum numbers of $0^{-+}$ and $1^{--}$. For the $Lambda$-$bar{Lambda}$, $Sigma$-$bar{Sigma}$, and $Xi$-$bar{Xi}$ states, their masses are found above the corresponding dibaryon thresholds, while the masses of $p$-$bar{p}$ states are not. The possible baryonium decay modes are analyzed, which are hopefully measurable in BESIII, BELLEII, and LHCb experiments.