We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties...We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties of the multiple images.By comparing with the classical dispersion relations,we find that one image has exhibited specific inverse properties to others,such as their delay times at high frequency is higher than that at low frequency,owing to the lensing effects of the plasma clump.We demonstrate that these inverse effects should be observable in some repeating FRBs.Our results predict deviation in the estimated dispersion measure(DM)across multiple images,consistent with the observations of FRB 121102 and FRB 180916.J0158+65.If other plasma lenses have effects similar to an exponential lens,we find that they should also give rise to a similar dispersion relation in the multiple images.For some repeating FRBs,analysis of the differences in time delay and in DM between multiple images at different frequencies can serve as a method to reveal the plasma distribution.展开更多
In this talk, I present the results on the pole structure of pion-nucleon scattering in an analytic model based on meson exchange. The analytic properties of scattering amplitudes provide important information. Beside...In this talk, I present the results on the pole structure of pion-nucleon scattering in an analytic model based on meson exchange. The analytic properties of scattering amplitudes provide important information. Besides the cuts, the poles and zeros on the different Riemann sheets determine the global behavior of the amplitude on the physical axis. Pole positions and residues allow for a parameterization of resonances in a well-defined way, free of assumptions for the background and energy dependence of the resonance part. This is a necessary condition to relate resonance contributions in different reactions.展开更多
The analytic properties theoretical investigations of baryon of scattering amplitudes provide a meeting point for experimental and resonances. Pole positions and residues allow for a parameterization of resonances in ...The analytic properties theoretical investigations of baryon of scattering amplitudes provide a meeting point for experimental and resonances. Pole positions and residues allow for a parameterization of resonances in a well-defined way which relates different reactions. The recent progress made within the Jiilich model is summarized.展开更多
In this paper we present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some...In this paper we present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. We also describe recent progress in performing geometrical fitting of the XANES (X-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach.展开更多
基金supported by the National Natural Science Foundation of China(grant Nos.12041304,11873080 and 12033001)supported by the 2021 project Xinjiang Uygur Autonomous Region of China for Tianshan elites,and the National SKA Program of China(grant Nos.U1838109,2020SKA0120100 and 12041301)+4 种基金supported by the Key Laboratory of Xinjiang Uygur Autonomous Region No.2020D04049the National SKA Program of China No.2020SKA0120200the 2018 Project of Xinjiang Uygur Autonomous Region of China for Flexibly Fetching in Upscale Talentssupported by CAS“Light of West China”Program No.2018-XBQNXZ-B-025partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the CAS。
文摘We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties of the multiple images.By comparing with the classical dispersion relations,we find that one image has exhibited specific inverse properties to others,such as their delay times at high frequency is higher than that at low frequency,owing to the lensing effects of the plasma clump.We demonstrate that these inverse effects should be observable in some repeating FRBs.Our results predict deviation in the estimated dispersion measure(DM)across multiple images,consistent with the observations of FRB 121102 and FRB 180916.J0158+65.If other plasma lenses have effects similar to an exponential lens,we find that they should also give rise to a similar dispersion relation in the multiple images.For some repeating FRBs,analysis of the differences in time delay and in DM between multiple images at different frequencies can serve as a method to reveal the plasma distribution.
基金Supported by DFG (Deutsche Forschungsgemeinschaft, Gz: DO 1302/1-1)Helmholtz Association through funds provided to the virtual institute 'Spin and Strong QCD' (VH-VI-231)EU-Research Infrastructure Integrating Activity 'Study of Strongly Interacting Matter' (Hadron Physics2 (227431)) under the Seventh Framework Program of EU and by the DFG (TR 16), COSY FFE (41445282)(COSY-58)
文摘In this talk, I present the results on the pole structure of pion-nucleon scattering in an analytic model based on meson exchange. The analytic properties of scattering amplitudes provide important information. Besides the cuts, the poles and zeros on the different Riemann sheets determine the global behavior of the amplitude on the physical axis. Pole positions and residues allow for a parameterization of resonances in a well-defined way, free of assumptions for the background and energy dependence of the resonance part. This is a necessary condition to relate resonance contributions in different reactions.
基金Supported by DFG (Deutsche Forschungsgemeinschaft, Gz: DO 1302/1-1)Helmholtz Association through funds provided to the virtual institute 'Spin and Strong QCD' (VH-VI-231)+1 种基金EU-Research Infrastructure Integrating Activity 'Study of Strongly Interacting Matter' (HadronPhysics2, grant n. 227431)under the Seventh Framework Program of EU and DFG (TR 16)COSY FFE grant No. 41445282 (COSY-58)
文摘The analytic properties theoretical investigations of baryon of scattering amplitudes provide a meeting point for experimental and resonances. Pole positions and residues allow for a parameterization of resonances in a well-defined way which relates different reactions. The recent progress made within the Jiilich model is summarized.
基金We would like to thank C.R.Natoli for iluminating discussion.Zi-Yu WU acknowledges the financial support of the 100-Talent Research Program of the Chinese Academy of Sciencesof the Outstanding Youth Fund(10125523)Key Important Nano-Research Project(90206032)of the National Natural Science Foundation of China.
文摘In this paper we present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. We also describe recent progress in performing geometrical fitting of the XANES (X-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach.
