How does the S11 N^*(890) state emerge from a naive K-matrix fit?  

作　　者：Yao Ma Wen-Qi Niu Yu-Fei Wang Han-Qing Zheng 

机构地区：[1]Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China [2]Helmholtz Institut für Strahlen-und Kernphysik,University of Bonn,Bonn D-53115,Germany [3]Collaborative Innovation Center of Quantum Matter,Beijing,China

出　　处：《Communications in Theoretical Physics》2020年第10期92-97,共6页理论物理通讯（英文版）

基　　金：supported in part by the National Nature Science Foundations of China under contract numbers 11975028 and 10925522;by the Sino-German CRC 110(Grant No.TRR110)。

摘　　要：We give a pedagogical analysis on K-matrix models describing theπN scattering amplitude,in S11 channel at low energies.We show how the correct use of analyticity in the s-channel and crossing symmetry in t-and u-channels leads to a much improved analytic behavior in the negative s region,in agreement with the prediction from chiral perturbation amplitudes in its validity region.The analysis leads again to the conclusion that a genuine N^*(890)resonance exists.

关 键 词：pi N scattering subthreshold pole K-MATRIX N^*(890) 

分 类 号：O571.412[理学—粒子物理与原子核物理]