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 N^* (920), with varying pion masses, in the scheme of linear model with nucleons using the N/D 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 one-loop level, the pole does not meet the u-cut up to m_=0. 36GeV. We also re-examined the pole trajectory and find it in good agreement with Roy equation analysis result. Content from this work may be used under the terms of the Creative Commons Attribution 3. 0 licence. Any further distribution of this work must maintain attribution to the author (s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.