Effective-Lagrangian study of $\psi'(J/\psi) \to VP$ and the insights into $\rho\pi$ puzzle

TL;DR

This study uses an effective Lagrangian approach to analyze $J/ar{J}$ decays into vector-pseudoscalar states, revealing the dominance of strong or electromagnetic interactions in different processes and providing insights into the $ ho extpi$ puzzle.

Contribution

It offers a unified analysis of $J/ar{J}$ decays and electromagnetic processes, clarifying the roles of strong and electromagnetic interactions and explaining the $ ho extpi$ puzzle.

Findings

Strong interaction dominates $J/ ho extpi$ decay.

Electromagnetic interaction dominates $ar{ extpi}$ decay.

Different $SU(3)$ breaking effects explain decay ratio differences.

Abstract

Within the effective Lagrangian approach, we carry out a unified study of the $J/\psi (\psi')\to VP$, $J/\psi \to P\gamma$ and relevant radiative decays of light-flavor hadrons. Large amount of experimental data, including the various decay widths and electromagnetic form factors, are fitted to constrain the numerous hadron couplings. Relative strengths between the strong and electromagnetic interactions are revealed in the $J/\psi \to VP$ and $\psi' \to VP$ processes. The effect from the strong interaction is found to dominate in the $J/\psi \to \rho\pi$ decay, while the electromagnetic interaction turns out to be the dominant effect in $\psi' \to \rho\pi$ decay, which provides an explanation to the $\rho\pi$ puzzle. For the $J/\psi\to K^{*}\bar{K}+\bar{K}^{*}K$ and $\psi' \to K^{*}\bar{K}+\bar{K}^{*}K$, the former process is dominated by the strong interactions, and the effects from the electromagnetic parts are found to be comparable with those of strong interactions in the latter process. Different $SU(3)$ breaking effects from the electromagnetic parts appear in the charged and neutral channels for the $\psi' \to K^{*}\bar{K}+\bar{K}^{*}K$ processes explain the rather different ratios between $B(\psi'\to K^{*+}K^{-}+K^{*-}K^{+})/B(J/\psi\to K^{*+}K^{-}+K^{*-}K^{+})$ and $B(\psi'\to K^{*0}\bar{K}^{0}+\bar{K}^{*0}K^{0})/B(J/\psi\to K^{*0}\bar{K}^{0}+\bar{K}^{*0}K^{0})$.