Recent N^* Results From J/\psi Decays

TL;DR

This paper reports the observation of two nucleon resonances, S11(1535) and S11(1650), in J/psi decay data, providing detailed mass and width measurements through partial wave analysis of selected decay channels.

Contribution

It presents new experimental evidence and precise measurements of nucleon resonances in J/psi decays, enhancing understanding of nucleon resonance spectrum.

Findings

Observation of two nucleon resonances S11(1535) and S11(1650)

Mass and width measurements of the resonances

Identification of peaks in invariant mass spectra

Abstract

Based on 7.8 million J/\psi events collected at BEPC, the events for J/\psi \to p\bar{p}\pi^0 and p\bar{p}\eta have been selected and reconstructed. Clear peaks are observed around 1480 MeV in p\pi^0 (\bar{p}\pi^0) invariant mass spectrum and near the threshold for $\eta$ production in p\eta(\bar{p}\eta) invariant mass spectrum. A partial wave analysis of J/\psi \to p\bar{p}\eta data has been performed. Two J^P={1/2}^- resonances are observed with mass and width (M, \Gamma) at (1540^{+15}_{-17}, 178^{+20}_{-22}) MeV and (1648^{+18}_{-16}, 150)MeV, and are considered to be the nucleon resonances S_{11}(1535) and S_{11}(1650) respectively.