Investigation of the $D^{0} \rightarrow K_S^{0} \pi^{0} \eta,\ K_S^{0} \pi^{0} \pi^0$ decays

TL;DR

This study models the decays $D^{0} ightarrow K_S^{0} ext{pseudoscalar mesons}$ using a combined chiral unitary approach, successfully reproducing experimental invariant mass spectra and identifying dynamically generated resonances.

Contribution

It introduces a unified formalism combining S-wave meson interactions and P-wave resonances to analyze these decay processes, providing new insights into resonance structures.

Findings

The $a_0(980)$ is dynamically generated from S-wave interactions.

Near-threshold enhancements are explained by $f_0(500)$ and $ar{K}^*(892)$ contributions.

Cusp structures are associated with the $f_0(980)$ resonance.

Abstract

Inspired by the invariant mass distributions for the decays $D^{0} \rightarrow K_S^{0} \pi^{0} \eta$ and $D^{0} \rightarrow K_S^{0} \pi^{0} \pi^{0}$ reported by the BESIII Collaboration, we investigate these processes with an unified final state interaction formalism by incorporating both the $S$-wave pseudoscalar meson-pseudoscalar meson interactions within a chiral unitary approach and the $P$-wave contribution from the intermediate resonance $\bar{K}^*(892)$. By performing a combined fit to the invariant mass spectra and taking into account the coherence between the $S$- and $P$-waves, our results are in agreement with the experimental data. For the decay $D^{0} \rightarrow K_S^{0} \pi^{0} \eta$, the structure near 1.0 GeV in the $\pi^0 \eta$ invariant mass distribution corresponds to the signal of the $a_{0}(980)$, which is dynamically generated from the $S$-wave interactions. In the case of $D^{0} \rightarrow K_S^{0} \pi^{0} \pi^{0}$, the near-threshold enhancement in the $\pi^0\pi^0$ mass distribution arises from the combined contributions of the $f_0(500)$ and the intermediate $\bar{K}^*(892)$, while the cusp-like structure around 1 GeV$^2$ is associated with the $f_0(980)$.