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

TL;DR

This study investigates the $X(4630)$ resonance in $e^+e^- ightarrow \Lambda_c^+ar{\Lambda}_c^-$ reactions near threshold, extracting its parameters and comparing with the $X(4660)$, while also predicting electromagnetic form factors.

Contribution

The paper provides a rigorous analysis of the $X(4630)$ resonance using chiral effective field theory and pole diagrams, offering updated resonance parameters and form factor predictions.

Findings

$X(4630)$ mass: 4652.5 MeV, width: 62.6 MeV

Resonance parameters compatible with $X(4660)$

Predictions for $\Lambda_c$ electromagnetic form factors

Abstract

The reaction $e^+e^-\rightarrow \Lambda^+_c\bar\Lambda^-_c$ 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.