On the pole trajectory of the subthreshold negative parity nucleon with varying pion masses*

Abstract We study the pole trajectory of the recently established subthreshold negative-parity nucleon pole, namely the , with varying pion masses in the scheme of linear σ model with nucleons, using the unitarization method. We find that, as the pion mass increases, the pole moves toward the real axis. For larger pion masses, at tree level, the pole falls to a specific point on u -channel cut and crosses to the adjacent Riemann sheet defined by the logarithmic u- channel cut. At the one-loop level, the pole does not meet the u -cut up to GeV. We also re-examined the σ pole trajectory and found it to be in good agreement with the Roy equation analysis result.