Ablikim, M (reprint author), Inst High Energy Phys, Beijing 100039, Peoples R China.
The decay J/psi ->(N) over barN pi provides an effective isospin 1/2 filter for the pi N system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi -> p pi(-)<<(n)over bar>+c.c. events are obtained. Besides the two well-known N-* peaks at around 1500 MeV/c(2) and 1670 MeV/c(2), there are two new, clear N-* peaks in the p pi invariant mass spectrum around 1360 MeV/c(2) and 2030 MeV/c(2) with statistical significance of 11 sigma and 13 sigma, respectively. We identify these as the first direct observation of the N-*(1440) peak and a long-sought missing N-* peak above 2 GeV/c(2) in the pi N invariant mass spectrum.