Evidence for narrow baryon resonances in inelastic pp scattering

The reaction pp --> p pi(+)N has been studied at three energies (T-p = 1520, 1805, and 2100 MeV) and six angles from 0 degrees up to 17 degrees (laboratory). Several narrow states have been observed in missing mass spectra at 1004, 1044, and 1094 MeV. Their widths are typically 1 order of magnitude smaller than the widths of N* or Delta. Possible biases are discussed. These masses are in good agreement with those calculated within a simple phenomenological mass formula based on color magnetic interaction between two colored quark clusters.