Re-examining the $X(4630)$ resonance in the reaction $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$

Abstract

The reaction $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ is investigated at energies close to the threshold with emphasis on the role played by the $X(4630)$ resonance. The interaction in the final ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ system, constructed within chiral effective field theory and supplemented by a pole diagram that represents a bare $X(4630)$ resonance, is taken into account rigorously. The pole parameters of the $X(4630)$ are extracted and found to be compatible with the ones of the $X(4660)$ resonance that have been established in the reaction $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\psi (2S)$. The actual result for the $X(4630)$ is $M=(4652.5\pm 3.4)$ MeV and $\Gamma =(62.6\pm 5.6)$ MeV. Predictions for the ${\Lambda }_c^{+}$ electromagnetic form factors in the timelike region are presented.

Comments: 11 pages, 3 figures