Spin-parity analysis of the diffractively produced low-mass Nπ system in the reaction π±p → π± (Nπ)+ at GeV/c

The dominant partial waves of the diffractively produced Nπ system at low Nπ masses (⩽ 1.4 GeV) are determined in the reactions π±p → π(Nπ) at 16 GeV/c. A satisfactory description of our data can only be obtained by strong contributions of both a 12− S-wave and a 32+ P-wave, violating the Gribov-Morrison rule. Spin and parity of the diffractively produced states are found from the interference between diffraction and Δ (1236) production. The interference term is obtained by an isospin analysis.