The N(1710)P11 state is confirmed in the re-analysis of the pi N --> K Lambda production; it is a good candidate for a non-strange pentaquark

Abstract

Re-analyzing the old pi N --> K Lambda data, the additional proof is given for the existence of the N(1710) P11 state, critically needed in light of reported observations of exotic Theta(1539) and Xi(1862) pentaquarks. An existing single-resonance model with S11, P11 and P13 Breit-Wiegner resonances in the s-channel has been applied. It has been shown that the standard set of resonant parameters fails to reproduce the shape of the differential cross section. The new resonance parameter determination has been performed keeping in mind the most recent knowledge about nucleon resonances. The extracted set of parameters has confirmed the need for the strong contribution of a N(1710) P11 resonance. The need for any significant contribution of the P13 resonance has been eliminated. To reproduce the total cross section at the same time with the linear dependence of the differential cross sections with the cos(theta) in the energy range 1650 MeV < W < 1800 MeV the P11 resonance can not but be quite narrow.