Meson Emission Model of Psi -> N Nbar m Charmonium Strong Decays

In this paper we consider a sequential "meson emission" mechanism for charmonium decays of the type $\Psi \to \NNm$, where $\Psi$ is a generic charmonium state, $N$ is a nucleon and $m$ is a light meson. This decay mechanism, which may not be dominant in general, assumes that an $\NN$ pair is created during charmonium annihilation, and the light meson $m$ is emitted from the outgoing nucleon or antinucleon line. A straightforward generalization of this model can incorporate intermediate $N^*$ resonances. We derive Dalitz plot event densities for the cases $\Psi = \eta_c$, $J/\psi$, $\chi_{c0}$, $\chi_{c1}$ and $\psi'$ and $m = \pi^0, f_0$ and $\omega$ (and implicitly, any $0^{-+}$, $0^{++}$ or $1^{--}$ final light meson). It may be possible to separate the contribution of this decay mechanism to the full decay amplitude through characteristic event densities. For the decay subset $\Psi \to \pppi$ the two model parameters are known, so we are able to predict absolute numerical partial widths for $\Gamma(\Psi\to \pppi)$. In the specific case $J/\psi \to \pppi$ the predicted partial width and $M_{p\pi}$ event distribution are intriguingly close to experiment. We also consider the possibility of scalar meson and glueball searches in $\Psi \to \ppf0$. If the meson emission contributions to $\Psi \to \NNm$ decays can be isolated and quantified, they can be used to estimate meson-nucleon strong couplings $\{g_{NNm}\}$, which are typically poorly known, and are a crucial input in meson exchange models of the $NN$ interaction. The determination of $g_{NN\pi}$ from $J/\psi \to \pppi$ and the (poorly known) $g_{NN\omega}$ and the anomalous ``strong magnetic" coupling $\kappa_{NN\omega}$ from $J/\psi \to \ppw$ are considered as examples.