Dispersive analysis of low energy yN→nN process and studies on the N*(890)resonance

• 来源期刊: 中国物理C（英文版）
• 年，卷（期）: 2021,（1）
• 所属期刊栏目: NUCLEAR PHYSICS
• 页码范围: 252-264
• 页数: 13页
• 语种: 英文
• DOI: 10.1088/1674-1137/abc169

摘要

We present a dispersive representation of the yN → nN partial-wave amplitude based on unitarity and analyticity.In this representation,the right-hand-cut contribution responsible for nN final-state-interaction effects is taken into account via an Omnes formalism with elastic πN phase shifts as inputs,while the left-hand-cut contribu-tion is estimated by invoking chiral perturbation theory.Numerical fits are performed to pin down the involved sub-traction constants.Good fit quality can be achieved with only one free parameter,and the experimental data regard-ing the multipole amplitude E+0 in the energy region below the A(1232)are well described.Furthermore,we extend the yN → nN partial-wave amplitude to the second Riemann sheet to extract the couplings of the N*(890).The modulus of the residue of the multipole amplitude E+0(S11pE)is 2.41 mfm.GeV2,and the partial width of N*(890)→ yN at the pole is approximately 0.369 MeV,which is almost the same as that of the N*(1535)reson-ance,indicating that N*(890)strongly couples to the nN system.