We have developed an analytic continuation method for extracting parameters of nucleon resonances within a Hamiltonian formulation of meson-nucleon reactions. The method was tested for simple solvable models and then ...We have developed an analytic continuation method for extracting parameters of nucleon resonances within a Hamiltonian formulation of meson-nucleon reactions. The method was tested for simple solvable models and then applied for our recent coupled channels model （πN, ηN, π△, ρN, and σN ） of the π＊N and γ＊N reactions. The resonance pole positions and their properties are studied for P11and P11 channels.展开更多
Abundant ψ＇ events have been collected at the Beijing Electron Positron Collider-Ⅱ （BEPCⅡ） that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been n...Abundant ψ＇ events have been collected at the Beijing Electron Positron Collider-Ⅱ （BEPCⅡ） that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of J/ψ＇ decaying to the baryonic final states, pK-Λ, the evident Λ＊ and N＊ bands have been observed. Similarly, by using the product of χcJ from ψ＇ radiative decay, we may confirm this or find some extra new resonances. χc0＇s data samples will be more than χc1,2, taking into account the larger branching ratio of ψ＇ →γχc0. Here, we provide explicit partial wave analysis formulae for the very interesting channel ψ＇ →γχc0 →γpK-Λ.展开更多
A chiral quark-model approach is employed to study theˉ KN scattering at low energies.The processes of Kˉp → Σ 0 π 0,Λπ 0 andˉ K 0 n at P K 800 MeV/c （i.e.the center mass energy W 1.7 GeV） are investigated.T...A chiral quark-model approach is employed to study theˉ KN scattering at low energies.The processes of Kˉp → Σ 0 π 0,Λπ 0 andˉ K 0 n at P K 800 MeV/c （i.e.the center mass energy W 1.7 GeV） are investigated.The analysis shows that the Λ（1405）S 01 dominates the processes Kˉp → Σ 0 π 0,ˉ K 0 n in the energy region considered here.Around P K 400 MeV/c,the Λ（1520）D 03 is responsible for a strong resonant peak in the cross section of Kˉp → Σ 0 π 0 andˉ K 0 n.To reproduce the data,an unexpectedly large coupling for Λ（1520）D 03 to KN is needed.In contrast,the coupling for Λ（1670）S 01 to KN appears to be weak,which could be due to configuration mixings between Λ（1405）S 01 and Λ（1670）S 01 .By analyzing Kˉ p → Λπ 0,evidences for two low mass S-wave states,Σ（1480）S 11 and Σ（1560）S 11,seem to be available.With these two states,the reaction Kˉp →ˉ K 0 n can also be described well.However,it is difficult to understand the low masses of Σ（1480）S 11 and Σ（1560）S 11 .The s-channel amplitudes for Kˉp → Λπ 0 are also larger than the naive quark model expectations.The non-resonant background contributions,i.e.t-channel and/or u-channel,also play important roles in the explanation of the angular distributions due to amplitude interferences.展开更多
A chiral quark-model approach is extended to the study of the KN scattering at low energies. The process of K-p →∑0π0 at PK 〈 800 MeV/c （i.e. the center mass energy W 〈 1.7 GeV） is investigated. The A（1405）S...A chiral quark-model approach is extended to the study of the KN scattering at low energies. The process of K-p →∑0π0 at PK 〈 800 MeV/c （i.e. the center mass energy W 〈 1.7 GeV） is investigated. The A（1405）S01 dominates the reactions over the energy region considered here. Around PK -- 400 MeV/c, the A（1520）D03 is responsible for a strong resonant peak in the cross section. Our analysis suggests that there exist configuration mixings within the A（1405）S01 and A（1670）S01 as admixtures of the [70,2 1,1/2] and [70,2 8,1/2] configurations. The A（1405）SOl is dominated by [70,2 1, 1/2], and A（1670）Sol by [70,2 8,1/2]. The non-resonant background contributions, i.e. u-channel and t-channel, also play important roles in the explanation of the angular distributions due to amplitude interferences.展开更多
A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer （CLAS）...A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer （CLAS） and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target （FROST） gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photopro- duction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.展开更多
最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论,该理论恰好是SU(6)夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现...最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论,该理论恰好是SU(6)夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现,重子共振态谱公式能够与2 Ge V以下重子谱良好吻合。展开更多
The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-...The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-lying poles in other channels,which have been extensively discussed in the literature,though they belong to different octets in the SU(3) limit.Hence,the existence of N^(*)(890) is further verified.展开更多
A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COS...A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COSY we show that this phenomenon is linked with a resonant energy dependence in the total cross section of isoscalar double-pionic fusion processes.This resonance structure is connected with the baryon-baryon system,in particular with the pn and ΔΔ systems,however,has a mass,which is 90 MeV below the nominal ΔΔ threshold and a width of only 70 MeV,i.e.,five times smaller than expected from a conventional t-channel ΔΔ scenario.展开更多
基金Supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research(C) 20540270U.S. Department of Energy, Office of Nuclear Physics Division, under contract No. DE-AC02-06CH11357Contract No. DE-AC05-060R23177 under which Jefferson Science Associates operates Jefferson Lab
文摘We have developed an analytic continuation method for extracting parameters of nucleon resonances within a Hamiltonian formulation of meson-nucleon reactions. The method was tested for simple solvable models and then applied for our recent coupled channels model （πN, ηN, π△, ρN, and σN ） of the π＊N and γ＊N reactions. The resonance pole positions and their properties are studied for P11and P11 channels.
基金Supported by Program for Innovative Research Team (in Science and Technology) at University of Henan Province, China(2010IRTSTHN002)National Natural Science Foundation of China (10521003, 10821063, 10835001, 10979008)100 Talents Program of CAS and the Knowledge Innovation Project of CAS (U-612, U-530) (IHEP)
文摘Abundant ψ＇ events have been collected at the Beijing Electron Positron Collider-Ⅱ （BEPCⅡ） that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of J/ψ＇ decaying to the baryonic final states, pK-Λ, the evident Λ＊ and N＊ bands have been observed. Similarly, by using the product of χcJ from ψ＇ radiative decay, we may confirm this or find some extra new resonances. χc0＇s data samples will be more than χc1,2, taking into account the larger branching ratio of ψ＇ →γχc0. Here, we provide explicit partial wave analysis formulae for the very interesting channel ψ＇ →γχc0 →γpK-Λ.
基金Supported by National Natural Science Foundation of China (10675131,10775145)Chinese Academy of Sciences (KJCX3-SYW-N2)
文摘A chiral quark-model approach is employed to study theˉ KN scattering at low energies.The processes of Kˉp → Σ 0 π 0,Λπ 0 andˉ K 0 n at P K 800 MeV/c （i.e.the center mass energy W 1.7 GeV） are investigated.The analysis shows that the Λ（1405）S 01 dominates the processes Kˉp → Σ 0 π 0,ˉ K 0 n in the energy region considered here.Around P K 400 MeV/c,the Λ（1520）D 03 is responsible for a strong resonant peak in the cross section of Kˉp → Σ 0 π 0 andˉ K 0 n.To reproduce the data,an unexpectedly large coupling for Λ（1520）D 03 to KN is needed.In contrast,the coupling for Λ（1670）S 01 to KN appears to be weak,which could be due to configuration mixings between Λ（1405）S 01 and Λ（1670）S 01 .By analyzing Kˉ p → Λπ 0,evidences for two low mass S-wave states,Σ（1480）S 11 and Σ（1560）S 11,seem to be available.With these two states,the reaction Kˉp →ˉ K 0 n can also be described well.However,it is difficult to understand the low masses of Σ（1480）S 11 and Σ（1560）S 11 .The s-channel amplitudes for Kˉp → Λπ 0 are also larger than the naive quark model expectations.The non-resonant background contributions,i.e.t-channel and/or u-channel,also play important roles in the explanation of the angular distributions due to amplitude interferences.
基金Supported by National Natural Science Foundation of China (10675131, 10775145)Chinese Academy of Sciences (KJCX3-SYW-N2)
文摘A chiral quark-model approach is extended to the study of the KN scattering at low energies. The process of K-p →∑0π0 at PK 〈 800 MeV/c （i.e. the center mass energy W 〈 1.7 GeV） is investigated. The A（1405）S01 dominates the reactions over the energy region considered here. Around PK -- 400 MeV/c, the A（1520）D03 is responsible for a strong resonant peak in the cross section. Our analysis suggests that there exist configuration mixings within the A（1405）S01 and A（1670）S01 as admixtures of the [70,2 1,1/2] and [70,2 8,1/2] configurations. The A（1405）SOl is dominated by [70,2 1, 1/2], and A（1670）Sol by [70,2 8,1/2]. The non-resonant background contributions, i.e. u-channel and t-channel, also play important roles in the explanation of the angular distributions due to amplitude interferences.
基金Supported by National Science Foundation, the U.S. Department of Energy (DOE)the French Centre National de la Recherche Scientifique and Commissariat à l’Energie Atomique, the Italian Istituto Nazionale di Fisica Nucleare, and the Korean Science,Engineering FoundationThe Southeastern Universities Research Association (SURA) operated Jefferson Lab for DOE under contract DE-AC05-84ER40150 during this work
文摘A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer （CLAS） and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target （FROST） gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photopro- duction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.
基金Supported in part by National Nature Science Foundations of China (11975028,10925522)。
文摘The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-lying poles in other channels,which have been extensively discussed in the literature,though they belong to different octets in the SU(3) limit.Hence,the existence of N^(*)(890) is further verified.
基金Supported by BMBF (06TU261,06TU9193)Forschungszentrum Jülich (COSY-FFE)DFG (Europ.Graduiertenkolleg 683)
文摘A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COSY we show that this phenomenon is linked with a resonant energy dependence in the total cross section of isoscalar double-pionic fusion processes.This resonance structure is connected with the baryon-baryon system,in particular with the pn and ΔΔ systems,however,has a mass,which is 90 MeV below the nominal ΔΔ threshold and a width of only 70 MeV,i.e.,five times smaller than expected from a conventional t-channel ΔΔ scenario.
