科研之友
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摘要
A production representation of partial-wave S matrix is utilized to construct low-energy elastic pion-nucleon scattering amplitudes from cuts and poles on complex Riemann sheets. Among them, the contribution of left-hand cuts is estimated using the ■(p3) results obtained in covariant baryon chiral perturbation theory within the extendedon-nass-shell scheme. By fitting to data on partial-wave phase shifts, it is indicated that the existences of hidden poles in S11 and P11 channels, as conjectured in our previous paper [Eur. Phys. J. C, 78(7): 543(2018)], are firmly established. Specifically, the pole mass of the S11 hidden resonance is determined to be(895±81)-(164±23)i MeV,whereas,the virtual pole in the P11 channel locates at(966±18) MeV. It is found that analyses at the■ (p3) level improves significantly the fit quality, comparing with the previous■ (p2) one. Quantitative studies with cautious physical discussions are also conducted for the other S-and P-wave channels.
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单位北京大学; 核物理与核技术国家重点实验室
