Recent Developments on Hadron Interaction and Dynamically Generated Resonances

In this talk I report on the recent developments in the subject of dynamically generated resonances. In particular I discuss the $gamma p to K^0 Sigma^+$ and $gamma n to K^0 Sigma^0$ reactions, with a peculiar behavior around the $K^{*0} Lambda$ threshold, due to a $1/2^-$ resonance around 2035 MeV. Similarly, I discuss a BES experiment, $J/psi to eta K^{*0} bar K^{*0}$ decay, which provides evidence for a new $h_1$ resonance around 1830 MeV that was predicted from the vector-vector interaction. A short discussion is then made about recent advances in the charm and beauty sectors.

$J/psi rightarrow pbar{p}phi$ decay in the isobar resonance model

Based on the effective Lagrangian approach, the $ J/psi to p bar{p} phi$ decay is studied in an isobar resonance model with the assumption that the $phi$-meson is produced from intermediate nucleon resonances. The contributions from the $N^*_{1/2^-}(1535)$, $N^*_{3/2^+}(1900)$, $N^*_{1/2^-}(2090)$ and $N^*_{1/2^+}(2100)$ states are considered. In terms of the coupling constants $g^{2}_{phi N N^{*}}$ and $g^{2}_{phi N N^{*}}$ extracted from the data of the partial decay widths of the $N^*$s to the $Npi$ channel, the reaction cross section of the $pi^{-}prightarrow nphi$ process and the partial decay widths of the $J/psirightarrow pbar{p}eta$ and $J/psirightarrow pbar{n}pi^{-}$ processes, respectively, the invariant mass spectrum and the Dalitz plot for $ J/psi to p bar{p} phi$ are predicted. It is shown that there are two types of results. In the type I case, a large peak structure around 2.09GeV implies that a considerable mount of $Nphi$ or $qqqsbar s$ component may exist in the narrow-width $N^*_{1/2^-}(2090)$ state, but for the wide-width $N^*_{1/2^+}(2100)$ state, it has little $qqqsbar s$ component. In the type II case, a small peak around 2.11GeV may only indicate the existence of a certain mount of $pphi$ or $qqqsbar s$ component in the narrow-width $N^*_{1/2^+}(2100)$ state, but no information for the wide-width $N^*_{1/2^-}(2090)$ state. Further BESIII data with high statistics would help us to distinguish the strange structures of these $N^*$s.