Charmed Baryonium
Abstract
We re-analyze the published data on the Y(4630) --> Lambdac Lambdabarc and the Y(4660) --> psi(2S) pi pi with a consistent Ansatz and we find that the two observations are likely to be due to the same state YB with MYB = 4660.7 +- 8.7 MeV and GammaYB = 61 +- 23 MeV. Under this hypothesis and reanalizing also the e+e- --> J/psi pi pi gammaISR spectrum we extract B(YB --> Lambdac Lambdabarc) / B(YB --> psi(2S) pi pi) = 25 +- 7, B(YB --> J/psi pi pi) / B(YB --> psi(2S) pi pi) < 0.46 @ 90% C.L., B(Y(4350) --> J/psi pi pi) / B(Y(4350) --> psi(2S) pi pi) < 3.4 x 10-3 @ 90% C.L. and B(YB --> psi(2S) sigma) / B (YB --> psi(2S) f0)=2.0 +- 0.3. These conclusions strongly support the hypothesis of YB being the first observation of a charmed baryonium constituted by four quarks. From the analysis of the mass spectrum and the decay properties we show that Y(4350) and YB are respectively consistent with the ground state and first radial excitation of the L=1 state.