The study of exotic structure of hadrons is fully achieved when reaction dynamics of the associated hadron productions is well understood. We employ as the standard mechanism the effective Lagrangian method and invest...The study of exotic structure of hadrons is fully achieved when reaction dynamics of the associated hadron productions is well understood. We employ as the standard mechanism the effective Lagrangian method and investigate several physical observables within the framework. The parameters are constrained by microscopic description of hadrons. We discuss photoproductions of kaon associated with the ground state A（1116） and its resonances A（1405） and A（1520）. In the former example we emphasize the meson cloud effect which significantly renormalizes the phenomenological parameters, while in the latter we discuss the features of the standard method. Finally we discuss briefly the N（1535） for the study of chiral symmetry of baryons. production of ηπ associated with the nucleon resonance展开更多
We study charmed baryon resonances that are generated dynamically from a coupled-channel unitary approach that implements heavy-quark symmetry. Some states can already be identified with experimental observations, suc...We study charmed baryon resonances that are generated dynamically from a coupled-channel unitary approach that implements heavy-quark symmetry. Some states can already be identified with experimental observations, such as Ac（2595）, Ac（2660）, Ec（2902） or Ac（2941）, while others need a compilation of more experimental data as well as an extension of the model to include higher order contributions. We also compare our model to previous SU（4） schemes.展开更多
If the number of colors N c is taken large,baryons and their excitations can be considered in a mean-field approach.We argue that the mean field in baryons breaks spontaneously the spherical and SU（3） flavor symmetr...If the number of colors N c is taken large,baryons and their excitations can be considered in a mean-field approach.We argue that the mean field in baryons breaks spontaneously the spherical and SU（3） flavor symmetries,but retains the SU（2） symmetry of simultaneous rotations in space and isospace.The one-quark and quark-hole excitations in the mean field,together with the SU（3） rotational bands about them determine the spectrum of baryon resonances,which turns out to be in good accordance with reality when one puts N c =3.A by-product of this scheme is a confirmation of the light pentaquark Θ ＋ baryon uudds as a typical Gamov–Teller resonance long known in nuclear physics.An extension of the same large-N c logic to charmed baryons leads to a prediction of a anti-decapenta （15）-plet of charmed pentaquarks,two of which,B ＋＋ c = cuuds and B ＋ c = cudds,may be light and stable with respect to strong decays.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
In this paper we discuss the reasons for our work towards establishing a new collaboration between Jefferson Lab （JLab） and the Institute of High Energy Physics （IHEP） in Beijing. We seek to combine experimentalis...In this paper we discuss the reasons for our work towards establishing a new collaboration between Jefferson Lab （JLab） and the Institute of High Energy Physics （IHEP） in Beijing. We seek to combine experimentalists and theorists into a dedicated group focused on better understanding the current and future data from JLab and from the Beijing Electron Positron Collider （BEPC）. Recent JLab results on the extraction of single- and double-polarization observables in both the lπ- and 2π-channel show their high sensitivity to small production amplitudes and therefore their importance for the extraction of resonance parameters. The Beijing Electron Spectrometer （BES） at the BEPC has collected high statistics data on J/ψ production. Its decay into baryon-antibaryon channels offers a unique and complementary way of probing nucleon resonances. The CEBAF Large Acceptance Spectrometer, CLAS, has access to N＊ form factors at high Q2 which is advantageous for the study of dynamical properties of nucleon resonances, while the low-background BES results will be able to provide guidance for the search for less-dominant excited states at JLab. Moreover, with the recently approved experimental proposal Nucleon Resonance Studies with CLAS12 and the high-quality data streaming from BES-Ⅲand CLAS, the time has come for forging a new Trans-Pacific collaboration of theorists and experimentalists on NSTAR physics.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
Baryon chiral perturbation theory （BChPT）, as an effective field theory of low-energy quantum chromodynamics （QCD）, has played and is still playing an important role in our understanding of non-perturbative strong...Baryon chiral perturbation theory （BChPT）, as an effective field theory of low-energy quantum chromodynamics （QCD）, has played and is still playing an important role in our understanding of non-perturbative strong-interaction phenomena. In the past two decades, inspired by the rapid progress in lattice QCD simulations and the new experimental campaign to study the strangeness sector of low-energy QCD, many efforts have been made to develop a fully covariant BChPT and to test its validity in all scenarios. These new endeavours have not only deepened our understanding of some long-standing problems, such as the power-counting-breaking problem and the convergence problem, but also resulted in theoretical tools that can be confidently applied to make robust predic- tions. Particularly, the manifestly covariant BChPT supplemented with the extended-on-mass-shell （EOMS） renormalization scheme has been shown to satisfy all analyticity and symmetry constraints and converge relatively faster compared to its non-relativistic and infrared counterparts. In this article, we provide a brief review of the fully covariant BChPT and its latest applications in the u, d, and s three-flavor sector.展开更多
We study the origin of baryon resonances which are dynamically generated in the chiral unitary approach. We propose a natural renormalization scheme for the dynamical generation of resonances using the low energy chir...We study the origin of baryon resonances which are dynamically generated in the chiral unitary approach. We propose a natural renormalization scheme for the dynamical generation of resonances using the low energy chiral interaction and a general feature of the scattering theory. A deviation of a phenomenological scattering amplitude from the natural one is interpreted by an effective pole term interaction of genuine nature which can not be described by the meson-baryon dynamics,reminiscent of the CDD pole. Applying the present method to physical meson-baryon scatterings,we find that the Λ(1405) resonance is dominated by a meson-baryon component forming a KN-πΣ molecular-like structure,while the N(1535) resonance requires some pole contribution.展开更多
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
In this work the mass spectra for some of the baryon resonances of the particle data group with three and four star status are obtained, and a unified description of the ground states and excitation spectra of baryons...In this work the mass spectra for some of the baryon resonances of the particle data group with three and four star status are obtained, and a unified description of the ground states and excitation spectra of baryons are provided in the framework of a non-relativistic potential model. For this goal we have analytically solved the radial SchrSdinger equation for three identical interacting particles with the anharmonic potential by using the Ansatz method and then we have calculated the baryon resonances spectrum by using the G/irsey Radicati mass formula （GR） and with generalized Giirsey Radicati mass formula （GGR）. The results of our model show that the calculated masses of baryon resonances by using the generalized Giirsey Radicati mass formula are found to be in good agreement with the tabulations of the Particle Data Group. The overall good description of the spectrum which we obtain shows that our model can also be used to give a fair description of the energies of the excited multiples up to 3 GeV mass and negative-parity resonance. Moreover, we have shown that our model reproduces the position of the Roper resonance of the nucleon.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
We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner.We analyze the behaviour in th...We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner.We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions.We discuss the implications of the in-medium properties of open-charm mesons on the D s0 （2317） and the predicted X（3700） scalar resonances.展开更多
基金Supported by Grant for Scientific Research Contract No. 19540297 from Ministry of Education, Culture, Science and Technology, Japan
文摘The study of exotic structure of hadrons is fully achieved when reaction dynamics of the associated hadron productions is well understood. We employ as the standard mechanism the effective Lagrangian method and investigate several physical observables within the framework. The parameters are constrained by microscopic description of hadrons. We discuss photoproductions of kaon associated with the ground state A（1116） and its resonances A（1405） and A（1520）. In the former example we emphasize the meson cloud effect which significantly renormalizes the phenomenological parameters, while in the latter we discuss the features of the standard method. Finally we discuss briefly the N（1535） for the study of chiral symmetry of baryons. production of ηπ associated with the nucleon resonance
基金Supported by EU contract FLAVIAnet MRTN-CT-2006-035482, by the contract FIS2008-01143 from MEC (Spain) and FEDERby the Generalitat de Catalunya contract 2005SGR-00343, and the Junta de Andalucía grants FQM225, FQM481 and P06-FQM-01735This research is part of the EU Integrated Infrastructure Initiative Hadron Physics Project under contractnumber RII3-CT-2004-506078
文摘We study charmed baryon resonances that are generated dynamically from a coupled-channel unitary approach that implements heavy-quark symmetry. Some states can already be identified with experimental observations, such as Ac（2595）, Ac（2660）, Ec（2902） or Ac（2941）, while others need a compilation of more experimental data as well as an extension of the model to include higher order contributions. We also compare our model to previous SU（4） schemes.
基金Supported by Russian Government grant RFBR-09-02-01198Mercator Fellowship,DFG,Germany
文摘If the number of colors N c is taken large,baryons and their excitations can be considered in a mean-field approach.We argue that the mean field in baryons breaks spontaneously the spherical and SU（3） flavor symmetries,but retains the SU（2） symmetry of simultaneous rotations in space and isospace.The one-quark and quark-hole excitations in the mean field,together with the SU（3） rotational bands about them determine the spectrum of baryon resonances,which turns out to be in good accordance with reality when one puts N c =3.A by-product of this scheme is a confirmation of the light pentaquark Θ ＋ baryon uudds as a typical Gamov–Teller resonance long known in nuclear physics.An extension of the same large-N c logic to charmed baryons leads to a prediction of a anti-decapenta （15）-plet of charmed pentaquarks,two of which,B ＋＋ c = cuuds and B ＋ c = cudds,may be light and stable with respect to strong decays.
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.
文摘In this paper we discuss the reasons for our work towards establishing a new collaboration between Jefferson Lab （JLab） and the Institute of High Energy Physics （IHEP） in Beijing. We seek to combine experimentalists and theorists into a dedicated group focused on better understanding the current and future data from JLab and from the Beijing Electron Positron Collider （BEPC）. Recent JLab results on the extraction of single- and double-polarization observables in both the lπ- and 2π-channel show their high sensitivity to small production amplitudes and therefore their importance for the extraction of resonance parameters. The Beijing Electron Spectrometer （BES） at the BEPC has collected high statistics data on J/ψ production. Its decay into baryon-antibaryon channels offers a unique and complementary way of probing nucleon resonances. The CEBAF Large Acceptance Spectrometer, CLAS, has access to N＊ form factors at high Q2 which is advantageous for the study of dynamical properties of nucleon resonances, while the low-background BES results will be able to provide guidance for the search for less-dominant excited states at JLab. Moreover, with the recently approved experimental proposal Nucleon Resonance Studies with CLAS12 and the high-quality data streaming from BES-Ⅲand CLAS, the time has come for forging a new Trans-Pacific collaboration of theorists and experimentalists on NSTAR physics.
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Acknowledgements L.S. Geng acknowledges fruitful discussions with L. Alvarez-Ruso, M. Altenbuchinger, N. Kaiser, J. Martin-Camalich, J. Meng, X.-L. Ren, H. Toki, M. J. Vicente Vacas, and W. Weise. This work was partly supported by the National Natural Science Foundation of China under Grant Nos. 11005007, 11035007, and 11175002, and the New Century Excellent Talents in University Program of Ministry of Education of China under Grant No. NCET- 10-0029.
文摘Baryon chiral perturbation theory （BChPT）, as an effective field theory of low-energy quantum chromodynamics （QCD）, has played and is still playing an important role in our understanding of non-perturbative strong-interaction phenomena. In the past two decades, inspired by the rapid progress in lattice QCD simulations and the new experimental campaign to study the strangeness sector of low-energy QCD, many efforts have been made to develop a fully covariant BChPT and to test its validity in all scenarios. These new endeavours have not only deepened our understanding of some long-standing problems, such as the power-counting-breaking problem and the convergence problem, but also resulted in theoretical tools that can be confidently applied to make robust predic- tions. Particularly, the manifestly covariant BChPT supplemented with the extended-on-mass-shell （EOMS） renormalization scheme has been shown to satisfy all analyticity and symmetry constraints and converge relatively faster compared to its non-relativistic and infrared counterparts. In this article, we provide a brief review of the fully covariant BChPT and its latest applications in the u, d, and s three-flavor sector.
基金Ministry of Education, Culture,Sports,Science and Technology,Japan(19540297,19853800,20028004)
文摘We study the origin of baryon resonances which are dynamically generated in the chiral unitary approach. We propose a natural renormalization scheme for the dynamical generation of resonances using the low energy chiral interaction and a general feature of the scattering theory. A deviation of a phenomenological scattering amplitude from the natural one is interpreted by an effective pole term interaction of genuine nature which can not be described by the meson-baryon dynamics,reminiscent of the CDD pole. Applying the present method to physical meson-baryon scatterings,we find that the Λ(1405) resonance is dominated by a meson-baryon component forming a KN-πΣ molecular-like structure,while the N(1535) resonance requires some pole contribution.
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.
文摘In this work the mass spectra for some of the baryon resonances of the particle data group with three and four star status are obtained, and a unified description of the ground states and excitation spectra of baryons are provided in the framework of a non-relativistic potential model. For this goal we have analytically solved the radial SchrSdinger equation for three identical interacting particles with the anharmonic potential by using the Ansatz method and then we have calculated the baryon resonances spectrum by using the G/irsey Radicati mass formula （GR） and with generalized Giirsey Radicati mass formula （GGR）. The results of our model show that the calculated masses of baryon resonances by using the generalized Giirsey Radicati mass formula are found to be in good agreement with the tabulations of the Particle Data Group. The overall good description of the spectrum which we obtain shows that our model can also be used to give a fair description of the energies of the excited multiples up to 3 GeV mass and negative-parity resonance. Moreover, we have shown that our model reproduces the position of the Roper resonance of the nucleon.
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.
基金partly supported by the EU contract No.MRTN-CT-2006- 035482 (FLAVIAnet)the contracts FIS2008-01661 and FIS2008-01143 from MICINN (Spain)+3 种基金the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042)the Generalitat de Catalunya contract 2009SGR-1289Junta de Andalucía under contract FQM225the support of the European Community-Research Infrastructure Integrating Activity 'Study of Strongly Interacting Matter' (HadronPhysics2,Grant Agreement n.227431) under the 7th Framework Programme of EU
文摘We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner.We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions.We discuss the implications of the in-medium properties of open-charm mesons on the D s0 （2317） and the predicted X（3700） scalar resonances.
