arXiv subjects
Publications and source records attributed to C Sabelli.
We reconsider the discrepancy between theory and data in the momentum distribution of slow J/psi in B decays. Beside an update of the standard color singlet and color octet QCD components, we include the contribution from XY Z exotic mesons, and show that the residual discrepancy could be accommodated considering new XYZ mesons still unobserved.
The discrepancy between theory and data in the momentum distribution of slow J/psi in B decays has been several times addressed as a puzzle. Using the most recent results on exclusive B decays into J/psi and heavy kaons or exotic mesons and reconsidering the non-relativistic-QCD calculation of the color octet fragmentation component, we show that an improvement in the comparison between data and theory can be obtained. There is still room for a better fit to data and this may imply that new exotic mesons of the XYZ kind have yet to be discovered.
In a recent paper we have proposed a method to estimate the prompt production cross section of X(3872) at the Tevatron assuming that this particle is a loosely bound molecule of a D and a D*bar meson. Under this hypothesis we find that it is impossible to explain the high prompt production cross section found by CDF at sigma(X(3872)) \sim 30-70 nb as our theoretical prediction is about 300 times smaller than the measured one. Following our work, Artoisenet and Braaten, have suggested that final state interactions in the DD*bar system might be so strong to push the result we obtained for the cross section up to the experimental value. Relying on their conclusions we show that the production of another very narrow loosely bound molecule, the X_s=D_s D_s*bar, could be similarly enhanced. X_s should then be detectable at CDF with a mass of 4080 MeV and a prompt production cross section of sigma(X_s) \sim 1-3 nb.
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. From the analysis of the mass spectrum and the decay properties we show that Y(4350) and Y_B are respectively consistent with the ground state and first radial excitation of the L=1 state.
The X(3872) is universally accepted to be an exotic hadron. In this letter we assume that the X(3872) is a D0 \bar D0* molecule, as claimed by many authors, and attempt an estimate of its prompt production cross section at Tevatron. A comparison with CDF data allows to draw some qualitative conclusions about this statement.