The Study Of π~-p→K~0∧ In A Chiral Quark Model

With a chiral quark model, we systematically studied the nucleon resonances with main quantum number(n≤ 2) in the reaction π-p → K0Λ when W<1.75 GeV,and learned the contributions of the relevant nucleon resonances to the scattering cross section. We also proved the coupling properties of the N*(1720)P13resonance in the reaction with the properties shown by strong decay.By studying the reaction π-p → K0Λ at low energies, we get that:(i) The reaction π-p → K0Λ is dominated by N*(1720)P13around threshold;(ii) The s-wave states, N*(1535)S11and N*(1650)S11, give some contribution in the scattering of K-p → Λη. While, the D-wave states, N*(1520)D13and N*(1710)D13have negligibly small contributions in this scattering process;(iii) The background contributions from t-channel and nucleon-pole are large, while the one from uchannel is small.It should remarked that we take N*(1720)P13resonance as a pure state when we ?t the experimental data. And we get that the mass of N*(1720)P13is M≈1690MeV, decay width Γ ≈ 110 MeV. Thus, the ?tted mass is smaller 30 MeV than the data from PDG(M~1720 MeV), and the ?tted decay width is very different from the one of central value in PDG(Γ ~250 MeV). In order to understand this behaviour, we studied the strong decay properties of N*(1720)P13. We get that when the mass of N*(1720)P13equals 1690 MeV, the total decay width is around120 MeV. We can see that the strong decay properties are highly agree with the properties extracted in scattering process.