Meson-baryon final-state interactions in the $\psi (3686)\to p{K}^{-}{K}_S^0{\bar{\Xi }}^0$ decay

Abstract

We study the decay $\psi (3686)\to p{K}^{-}{\bar{K}}^0{\bar{\Xi }}^0$, treating the $\psi (3686)$ as a $c\bar{c}$ state and therefore as a singlet under SU(3) transformations in the light-quark sector. We consider all possible combinations of a baryon, an antibaryon, and two pseudoscalar mesons that form an SU(3) singlet, retaining the terms that can lead to the $p{K}^{-}{\bar{K}}^0{\bar{\Xi }}^0$ final state through $S$-wave final-state interactions. Three independent SU(3)-singlet structures are identified and assigned different weights. We also include the contribution of the $\Lambda (1520)$ in the meson-baryon $D$-wave. A fit to the data provides a good description of all six invariant-mass distributions. In addition to the $\Lambda (1520)$ contribution, we find a small contribution from the $\Lambda (1670)$ in the $K^{-}p$ invariant-mass distribution, generated by final-state interactions, and a contribution from the $\Sigma (1430)$, which produces a significant distortion of the ${\bar{K}}^{0}p$ invariant-mass distribution relative to phase space. This study demonstrates the value of investigating charmonium decays into a baryon-antibaryon pair and two pseudoscalar mesons, complementing the more commonly studied decays into a baryon-antibaryon pair and a single pseudoscalar meson.

arXiv comment15 pages, 9 figures