# Triangle singularity in the $J/\psi \rightarrow K^+ K^- f_0(980)(a_0(980))$ decays

## TL;DR

This paper investigates the decay process of J/psi into K+ K- and scalar mesons f0(980) or a0(980), revealing a triangle singularity that enhances the decay rate and offers insights into the nature of these scalar mesons.

## Contribution

It identifies a triangle singularity in J/psi decays involving scalar mesons, linking it to their dynamical generation from pseudoscalar meson interactions.

## Key findings

- Triangle singularity appears around 1515 MeV in the decay process.
- Differential decay width shows rapid growth near the singularity.
- Branching ratios are around 10^{-5}, accessible experimentally.

## Abstract

We study the $J/\psi \rightarrow K^+ K^- f_0(980)(a_0(980))$ reaction and find that the mechanism to produce this decay develops a triangle singularity around $M_{\rm inv}(K^- f_0/K^- a_0) \approx 1515$~MeV. The differential width $d\Gamma / dM_{\rm inv}(K^- f_0/K^- a_0)$ shows a rapid growth around the invariant mass being 1515~MeV as a consequence of the triangle singularity of this mechanism, which is directly tied to the nature of the $f_0(980)$ and $a_0(980)$ as dynamically generated resonances from the interaction of pseudoscalar mesons. The branching ratios obtained for the $J/\psi \rightarrow K^+ K^- f_0(980)(a_0(980))$ decays are of the order of $10^{-5}$, accessible in present facilities, and we argue that their observation should provide relevant information concerning the nature of the low-lying scalar mesons.