Production and mixing of scalar mesons in $\eta_c$ and $\chi_{c1}$ decays

TL;DR

This paper uses a chiral unitary approach to describe scalar meson production in charmonium decays, comparing predictions with experimental data and exploring meson mixing phenomena to understand their dynamical origins.

Contribution

It applies a coupled-channel chiral unitary model to charmonium decays, providing predictions and insights into scalar meson production and mixing, supporting their dynamical generation from pseudoscalar interactions.

Findings

Strong a0(980) peak observed in chi_c1 decay

Predictions for eta_c decay channels align with experimental trends

Quantitative agreement on a0(980)-f0(980) mixing from BESIII data

Abstract

We briefly discuss how the chiral unitary approach in coupled channels and $SU(3)$ symmetry can be used to describe the production of $f_0(500)$, $f_0(980)$ and $a_0(980)$ in the $\chi_{c1} \to \eta \pi^+ \pi^-$ reaction, recently measured by the BESIII collaboration. In this reaction a very strong peak for the $a_0(980)$ can be seen in the $\eta\pi$ invariant mass, while clear signals for the $f_0(500)$ and $f_0(980)$ appear in the one of $\pi^+\pi^-$. Next, we show the predictions made with the same model for the analogous decay $\eta_c \to \eta \pi^+ \pi^-$, which could also be measured experimentally. We discuss the differences of these two reactions which are interesting to test the picture where these scalar mesons are dynamically generated from the interaction of pairs of pseudoscalars. Furthermore, we comment on a new recent work where the same model was used to study the $a_0(980) - f_0(980)$ mixing in the $\chi_{c1} \to \pi^0 \pi^0 \eta$ and $\chi_{c1} \to \pi^0 \pi^+ \pi^-$ reactions, showing that quantitative agreement with the experimental measurement of this mixing, also performed by BESIII, can be obtained, revealing interesting aspects of the dynamics of this process and the importance of coupled channels.