Charmed Baryonium

Understand

We re-analyze the published data on the Y(4630) --> Lambda_c Lambdabar_c 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 Y_B with M_{Y_B} = 4660.7 +- 8.7 MeV and Gamma_{Y_B} = 61 +- 23 MeV.

• Under this hypothesis and reanalizing also the e+e- --> J/psi pi pi gamma_ISR spectrum we extract B(Y_B --> Lambda_c Lambdabar_c) / B(Y_B --> psi(2S) pi pi) = 25 +- 7, B(Y_B --> J/psi pi pi) / B(Y_B --> 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(Y_B --> psi(2S) sigma) / B (Y_B --> psi(2S) f_0)=2.0 +- 0.3.
• These conclusions strongly support the hypothesis of Y_B being the first observation of a charmed baryonium constituted by four quarks.