The $\rho - \pi$ Puzzle of J/\psi and \psi' Decays

TL;DR

This paper discusses the $ ho - \pi$ puzzle in $J/\psi$ and $\psi'$ decays, analyzing recent BES data to address theoretical challenges and explore decay modes with implications for understanding charmonium decay mechanisms.

Contribution

It provides a detailed analysis of recent experimental data on $\psi'$ decays, offering insights into the longstanding $ ho - \pi$ puzzle and proposing directions for future measurements.

Findings

Observation of isospin violating decay $\psi' o \pi^0 \omega^0$

Finite branching ratio for $\psi' o K^{*0} ar{K}^0$

Questions about $\psi' o \pi^+\pi^-$ and $K^{*+} K^-$ modes remain open

Abstract

The recent BES Collaboration data on $\psi' \ra PV$, particularly the isospin violating mode $\psi' \ra \pi^0 \omega^0$ and finding of a finite number for $B(\psi' \ra K^{*0}\bar{K}^0)$, enable us now to deal more precisely about the challenges to theory concerning this extraordinary and remarkable so called $\rho - \pi$ Puzzle of $J/\psi$ and $\psi'$ Decays. In terms of existing data, and deploying the simplest phenomenology, measurement of $\psi' \ra \pi^+\pi^-$ and whether a finite number for the $K^{*+} K^-$ mode might require a significantly larger accumulation of data, remain interesting questions.