Kanzo Nakayama
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The organizations/institutes from the scholar's latest article
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The organizations / institutes from the scholar's other articles in the past ten years
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Kanzo Nakayama has a total of 70 co-authors. Here are the top co-authors by number of shared publications:
- Helmut Haberzettl
Institute for Nuclear Studies and Department of Physics, The George Washington University, Washington, DC 20052, USA
28 shared publications - Yongseok Oh
Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 37673, Korea
19 shared publications - Fei Huang
University of Chinese Academy of Sciences
10 shared publications - Michael Doering
The George Washington University
5 shared publications - Maxim Mai
The George Washington University
3 shared publications - A. Johansson
Department of Physics and Astronomy Uppsala University Box 535 S-751 21 Uppsala Sweden
2 shared publications
Latest Publications
- Open Access
- 19 May 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 105 (9) , 094017
Nucleon and resonances in photoproductionThe most recent data on beam asymmetries and beam-target asymmetries from the CLAS Collaboration, together with the previous data on differential cross sections and beam asymmetries from the CLAS and LEPS Collaborations, for the reaction are studied based on an effective Lagrangian approach in the tree-level Born approximation. The -channel and exchanges, the -channel exchange, the interaction current, and the exchanges of , , and their excited states in the channel are considered in constructing the reaction amplitudes to describe the available experimental data. The reaction mechanisms of are analyzed, and the associated resonances’ parameters are extracted. The numerical results show that the exchange and the , , , and resonance exchanges in the channel dominate the reaction in the lower energy region, and the -channel exchange plays a crucial role at forward angles in the higher energy region.- 19 May 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 105 (9) , 094017
Open AccessNucleon and resonances in photoproductionThe most recent data on beam asymmetries and beam-target asymmetries from the CLAS Collaboration, together with the previous data on differential cross sections and beam asymmetries from the CLAS and LEPS Collaborations, for the reaction are studied based on an effective Lagrangian approach in the tree-level Born approximation. The -channel and exchanges, the -channel exchange, the interaction current, and the exchanges of , , and their excited states in the channel are considered in constructing the reaction amplitudes to describe the available experimental data. The reaction mechanisms of are analyzed, and the associated resonances’ parameters are extracted. The numerical results show that the exchange and the , , , and resonance exchanges in the channel dominate the reaction in the lower energy region, and the -channel exchange plays a crucial role at forward angles in the higher energy region. - Open Access
Complex phase structure of the meson-baryon $T$-matrix
The full complex phase structure of the meson-baryon reaction amplitude in coupled channels approach is investigated, including also the photon-baryon channel. The result may be viewed as a generalization of the well-known Watson's theorem. Furthermore, the complex phase structure is exhibited for the pole and nonpole parts of the reaction amplitude in such a way that it will serve as a convenient common starting point for constructing models with different levels of approximation, in particular, for building isobar models where the basic properties of the $S$-matrix can be maintained. Such models should be useful, especially, in coupled multichannel calculations, where a large amount of experimental data are considered in resonance analyses, a situation encountered in modern baryon spectroscopy. In particular, it is shown that the unitarity of the pole part of the $T$-matrix arises automatically from the dressing mechanism inherent in the basic scattering equation. This implies that no separate conditions are required for making this part of the resonance amplitude unitary as it has been done in some of the existing isobar models.
Open AccessComplex phase structure of the meson-baryon $T$-matrix
The full complex phase structure of the meson-baryon reaction amplitude in coupled channels approach is investigated, including also the photon-baryon channel. The result may be viewed as a generalization of the well-known Watson's theorem. Furthermore, the complex phase structure is exhibited for the pole and nonpole parts of the reaction amplitude in such a way that it will serve as a convenient common starting point for constructing models with different levels of approximation, in particular, for building isobar models where the basic properties of the $S$-matrix can be maintained. Such models should be useful, especially, in coupled multichannel calculations, where a large amount of experimental data are considered in resonance analyses, a situation encountered in modern baryon spectroscopy. In particular, it is shown that the unitarity of the pole part of the $T$-matrix arises automatically from the dressing mechanism inherent in the basic scattering equation. This implies that no separate conditions are required for making this part of the resonance amplitude unitary as it has been done in some of the existing isobar models.
- 23 December 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 100 (11) , 114036
Complex phase structure of the meson-baryon -matrixThe full complex phase structure of the meson-baryon reaction amplitude in coupled channels approach is investigated, including also the photon-baryon channel. The result may be viewed as a generalization of the well-known Watson’s theorem. Furthermore, the complex phase structure is exhibited for the pole and nonpole parts of the reaction amplitude in such a way that it will serve as a convenient common starting point for constructing models with different levels of approximation, in particular, for building isobar models where the basic properties of the -matrix can be maintained. Such models should be useful, especially, in coupled multichannel calculations, where a large amount of experimental data are considered in resonance analyses, a situation encountered in modern baryon spectroscopy. In particular, it is shown that the unitarity of the pole part of the -matrix arises automatically from the dressing mechanism inherent in the basic scattering equation. This implies that no separate conditions are required for making this part of the amplitude unitary as it has been done in some of the existing isobar models.- 23 December 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 100 (11) , 114036
Complex phase structure of the meson-baryon -matrixThe full complex phase structure of the meson-baryon reaction amplitude in coupled channels approach is investigated, including also the photon-baryon channel. The result may be viewed as a generalization of the well-known Watson’s theorem. Furthermore, the complex phase structure is exhibited for the pole and nonpole parts of the reaction amplitude in such a way that it will serve as a convenient common starting point for constructing models with different levels of approximation, in particular, for building isobar models where the basic properties of the -matrix can be maintained. Such models should be useful, especially, in coupled multichannel calculations, where a large amount of experimental data are considered in resonance analyses, a situation encountered in modern baryon spectroscopy. In particular, it is shown that the unitarity of the pole part of the -matrix arises automatically from the dressing mechanism inherent in the basic scattering equation. This implies that no separate conditions are required for making this part of the amplitude unitary as it has been done in some of the existing isobar models.- Open Access
- 16 December 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 100 (11) , 114026
Nucleon resonances in reactionThe most recent high-precision data on spin observables , , , , , and reported by the CLAS Collaboration together with the previous data on differential cross sections and spin-density-matrix elements reported by the CLAS, A2, GRAAL, SAPHIR, and CBELSA/TAPS Collaborations for the reaction are analyzed within an effective Lagrangian approach. The reaction amplitude is constructed by considering the -channel and exchanges, the -channel nucleon and nucleon resonances exchanges, the -channel nucleon exchange, and the generalized contact current. The latter accounts effectively for the interaction current and ensures that the full photoproduction amplitude is gauge invariant. It is shown that all the available CLAS data can be satisfactorily described by considering the , , , , , , and resonances in the -channel. The parameters of these resonances are extracted and compared with those quoted by PDG.- 16 December 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 100 (11) , 114026
Open AccessNucleon resonances in reactionThe most recent high-precision data on spin observables , , , , , and reported by the CLAS Collaboration together with the previous data on differential cross sections and spin-density-matrix elements reported by the CLAS, A2, GRAAL, SAPHIR, and CBELSA/TAPS Collaborations for the reaction are analyzed within an effective Lagrangian approach. The reaction amplitude is constructed by considering the -channel and exchanges, the -channel nucleon and nucleon resonances exchanges, the -channel nucleon exchange, and the generalized contact current. The latter accounts effectively for the interaction current and ensures that the full photoproduction amplitude is gauge invariant. It is shown that all the available CLAS data can be satisfactorily described by considering the , , , , , , and resonances in the -channel. The parameters of these resonances are extracted and compared with those quoted by PDG. - 30 September 2019
- Published by American Physical Society (APS) in Physical Review C
- Vol. 100 (3) , 035208
Explicit derivation of the completeness condition in pseudoscalar meson photoproduction
By exploiting the underlying symmetries of the relative phases of the pseudoscalar meson photoproduction amplitude, we provide a consistent and explicit mathematical derivation of the completeness condition for the observables in this reaction. In particular, we determine all the possible sets of four double-spin observables that resolve the phase ambiguity of the amplitude in transversity basis up to an overall phase. The present work substantiates and corroborates the original findings of Chiang and Tabakin [ Phys. Rev. C 55, 2054 (1997)]. It is found, however, that the completeness condition of four double-spin observables to resolve the phase ambiguity holds only when the relative phases do not meet the condition of equal magnitudes. In situations where this condition occurs, it is shown that one needs extra chosen observables, resulting in the minimum number of observables required to resolve the phase ambiguity reaching up to eight, depending on the particular set of four double-spin observables considered. Furthermore, a way of gauging when the condition of equal magnitudes occurs is provided.
- 30 September 2019
- Published by American Physical Society (APS) in Physical Review C
- Vol. 100 (3) , 035208
Explicit derivation of the completeness condition in pseudoscalar meson photoproduction
By exploiting the underlying symmetries of the relative phases of the pseudoscalar meson photoproduction amplitude, we provide a consistent and explicit mathematical derivation of the completeness condition for the observables in this reaction. In particular, we determine all the possible sets of four double-spin observables that resolve the phase ambiguity of the amplitude in transversity basis up to an overall phase. The present work substantiates and corroborates the original findings of Chiang and Tabakin [ Phys. Rev. C 55, 2054 (1997)]. It is found, however, that the completeness condition of four double-spin observables to resolve the phase ambiguity holds only when the relative phases do not meet the condition of equal magnitudes. In situations where this condition occurs, it is shown that one needs extra chosen observables, resulting in the minimum number of observables required to resolve the phase ambiguity reaching up to eight, depending on the particular set of four double-spin observables considered. Furthermore, a way of gauging when the condition of equal magnitudes occurs is provided.
- Open Access
On the spin-observables in pseudoscalar meson photoproduction
Spin-observables in pseudoscalar meson photoproduction is discussed. This work is complementary to the earlier works on this topic. Here, the reaction amplitude is expressed in Pauli-spin basis which allows to calculate all the observables straightforwardly. We make use of the fact that the underlying reflection symmetry about the reaction plane can be most conveniently and easily exploited in this basis to help finding the non-vanishing and independent observables in this reaction. The important issue of complete experiments is reviewed. By expressing the reaction amplitude in Pauli-spin basis, many sets of eight observables - distinct from those found in earlier works from the amplitude in transversity basis - capable of determining the reaction amplitude up to an overall phase are found. It is also shown that some of the combinations of the spin observables are suited for studying certain aspects of the reaction dynamics. We, then, carry out a (strictly) model-independent partial-wave analysis, in particular, of the peculiar angular behavior of the beam asymmetry observed in eta' photoproduction very close to threshold [P. Levi Sandri et al. 2015 Eur. Phys. J. A 51, 77]. This work should be useful, especially, for newcomers in the field of baryon spectroscopy, where the photoproduction reactions are a major tool for probing the baryon spectra.
Open AccessOn the spin-observables in pseudoscalar meson photoproduction
Spin-observables in pseudoscalar meson photoproduction is discussed. This work is complementary to the earlier works on this topic. Here, the reaction amplitude is expressed in Pauli-spin basis which allows to calculate all the observables straightforwardly. We make use of the fact that the underlying reflection symmetry about the reaction plane can be most conveniently and easily exploited in this basis to help finding the non-vanishing and independent observables in this reaction. The important issue of complete experiments is reviewed. By expressing the reaction amplitude in Pauli-spin basis, many sets of eight observables - distinct from those found in earlier works from the amplitude in transversity basis - capable of determining the reaction amplitude up to an overall phase are found. It is also shown that some of the combinations of the spin observables are suited for studying certain aspects of the reaction dynamics. We, then, carry out a (strictly) model-independent partial-wave analysis, in particular, of the peculiar angular behavior of the beam asymmetry observed in eta' photoproduction very close to threshold [P. Levi Sandri et al. 2015 Eur. Phys. J. A 51, 77]. This work should be useful, especially, for newcomers in the field of baryon spectroscopy, where the photoproduction reactions are a major tool for probing the baryon spectra.
- 2 September 2019
- Published by IOP Publishing in Journal of Physics G: Nuclear and Particle Physics
- Vol. 46 (10) , 105108
On the spin-observables in pseudoscalar meson photoproduction
Spin-observables in pseudoscalar meson photoproduction are discussed. This work is complementary to the earlier works on this topic. Here, the reaction amplitude is expressed in Pauli-spin basis which allows to calculate all the observables straightforwardly. We make use of the fact that the underlying reflection symmetry about the reaction plane can be most conveniently and easily exploited in this basis to help find the non-vanishing and independent observables in this reaction. The important issue of complete experiments is reviewed. By expressing the reaction amplitude in Pauli-spin basis, many sets of eight observables—distinct from those found in earlier works from the amplitude in transversity basis—capable of determining the reaction amplitude up to an overall phase are found. It is also shown that some of the combinations of the spin observables are suited for studying certain aspects of the reaction dynamics. We, then, carry out a (strictly) model-independent partial-wave analysis, in particular, of the peculiar angular behavior of the beam asymmetry observed in η ′ photoproduction very close to threshold (Levi Sandri et al 2015 Eur. Phys. J. A 51 77). This work should be useful, especially, for newcomers in the field of baryon spectroscopy, where the photoproduction reactions are a major tool for probing the baryon spectra.
- 2 September 2019
- Published by IOP Publishing in Journal of Physics G: Nuclear and Particle Physics
- Vol. 46 (10) , 105108
On the spin-observables in pseudoscalar meson photoproduction
Spin-observables in pseudoscalar meson photoproduction are discussed. This work is complementary to the earlier works on this topic. Here, the reaction amplitude is expressed in Pauli-spin basis which allows to calculate all the observables straightforwardly. We make use of the fact that the underlying reflection symmetry about the reaction plane can be most conveniently and easily exploited in this basis to help find the non-vanishing and independent observables in this reaction. The important issue of complete experiments is reviewed. By expressing the reaction amplitude in Pauli-spin basis, many sets of eight observables—distinct from those found in earlier works from the amplitude in transversity basis—capable of determining the reaction amplitude up to an overall phase are found. It is also shown that some of the combinations of the spin observables are suited for studying certain aspects of the reaction dynamics. We, then, carry out a (strictly) model-independent partial-wave analysis, in particular, of the peculiar angular behavior of the beam asymmetry observed in η ′ photoproduction very close to threshold (Levi Sandri et al 2015 Eur. Phys. J. A 51 77). This work should be useful, especially, for newcomers in the field of baryon spectroscopy, where the photoproduction reactions are a major tool for probing the baryon spectra.
- Open Access
- 8 March 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 99 (5) , 053001
Theory of two-meson photo- and electroproduction off the nucleon
Using the reaction as the paradigmatic topological framework, a field-theoretical description of the electromagnetic production of two pseudoscalar mesons off the nucleon is derived and applied to photo- and electroproduction processes, assuming only one-photon exchange for the latter. The dynamics of all explicit three-point interaction mechanisms of the system is accounted for by the Faddeev-type ordering structure of the Alt-Grassberger-Sandhas equations. The modifications necessary for incorporating -meson vertices for are discussed. The formulation is valid for hadronic two-point and three-point functions dressed by arbitrary (even nonlinear) internal mechanisms provided all associated electromagnetic currents are constructed to satisfy their respective (generalized) Ward-Takahashi identities. Coupling the photon to the Faddeev structure of the underlying hadronic two-pion production mechanisms results in a natural expansion of the full two-pion photoproduction current in terms of multiple dressed loops involving two-body subsystem scattering amplitudes of the system that preserves gauge invariance as a matter of course order by order in the number of (dressed) loops. A closed-form expression is presented for the entire gauge-invariant current with complete three-body dynamics. Individually gauge-invariant truncations of the full dynamics most relevant for practical applications at the no-loop, one-loop, and two-loop levels are discussed in detail. An approximation scheme to the full two-meson amplitude for calculational purposes is also presented. It approximates, systematically, the full amplitude to any desired order of expansion in the underlying hadronic two-body amplitude. Moreover, it allows for the approximate incorporation of all neglected higher-order mechanisms in terms of a locally gauge-invariant phenomenological remainder current.- 8 March 2019
- Published by American Physical Society (APS) in Physical Review D
- Vol. 99 (5) , 053001
Open AccessTheory of two-meson photo- and electroproduction off the nucleon
Using the reaction as the paradigmatic topological framework, a field-theoretical description of the electromagnetic production of two pseudoscalar mesons off the nucleon is derived and applied to photo- and electroproduction processes, assuming only one-photon exchange for the latter. The dynamics of all explicit three-point interaction mechanisms of the system is accounted for by the Faddeev-type ordering structure of the Alt-Grassberger-Sandhas equations. The modifications necessary for incorporating -meson vertices for are discussed. The formulation is valid for hadronic two-point and three-point functions dressed by arbitrary (even nonlinear) internal mechanisms provided all associated electromagnetic currents are constructed to satisfy their respective (generalized) Ward-Takahashi identities. Coupling the photon to the Faddeev structure of the underlying hadronic two-pion production mechanisms results in a natural expansion of the full two-pion photoproduction current in terms of multiple dressed loops involving two-body subsystem scattering amplitudes of the system that preserves gauge invariance as a matter of course order by order in the number of (dressed) loops. A closed-form expression is presented for the entire gauge-invariant current with complete three-body dynamics. Individually gauge-invariant truncations of the full dynamics most relevant for practical applications at the no-loop, one-loop, and two-loop levels are discussed in detail. An approximation scheme to the full two-meson amplitude for calculational purposes is also presented. It approximates, systematically, the full amplitude to any desired order of expansion in the underlying hadronic two-body amplitude. Moreover, it allows for the approximate incorporation of all neglected higher-order mechanisms in terms of a locally gauge-invariant phenomenological remainder current. - Open AccessPossible $S$-wave $ND^{(*)}$ and $N\bar B^{(*)}$ bound states in a chiral quark model$S$-wave bound-states composed of a nucleon($N$) and a heavy meson ($D$, $D^*$, $\bar{B}$ or $\bar{B}^*$) are investigated in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the resonating group method equation. The results reveal that the $ND$ and $ND^*$ interactions in the corresponding relative $S$-wave states are attractive, arising mainly from one boson exchange processes between light quarks. It is shown that these attractions are strong enough to form six $ND$ and $ND^*$ $S$-wave bound states in the extended chiral SU(3) quark model with the binding energies in the range of $3-45$ MeV, and three $S$-wave bound states within the chiral SU(3) quark model with binding energies of $2-8$ MeV. In particular, the experimentally observed $\Sigma_c(2800)$ is interpreted to be most likely an $S-$wave $ND$ state with the total isopsin $I=0$ and spin-parity $J^P=1/2^-$, while $\Lambda_c(2940)^+$ as an $S-$wave $ND^*$ state with $I=0$ and $J^P=3/2^-$. Further information on the $ND$ and $ND^*$ interactions in the (unbound) scattering kinematics are obtained from the corresponding $S$-wave phase shifts. The $N\bar{B}$ and $N\bar{B}^*$ systems are also investigated within the present two models and some $S-$wave bound states with binding energies in the range of $1-60$ MeV are predicted in these systems: six (in total) within the extended chiral SU(3) quark model and, four, within the chiral SU(3) quark model.Open AccessPossible $S$-wave $ND^{(*)}$ and $N\bar B^{(*)}$ bound states in a chiral quark model$S$-wave bound-states composed of a nucleon($N$) and a heavy meson ($D$, $D^*$, $\bar{B}$ or $\bar{B}^*$) are investigated in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the resonating group method equation. The results reveal that the $ND$ and $ND^*$ interactions in the corresponding relative $S$-wave states are attractive, arising mainly from one boson exchange processes between light quarks. It is shown that these attractions are strong enough to form six $ND$ and $ND^*$ $S$-wave bound states in the extended chiral SU(3) quark model with the binding energies in the range of $3-45$ MeV, and three $S$-wave bound states within the chiral SU(3) quark model with binding energies of $2-8$ MeV. In particular, the experimentally observed $\Sigma_c(2800)$ is interpreted to be most likely an $S-$wave $ND$ state with the total isopsin $I=0$ and spin-parity $J^P=1/2^-$, while $\Lambda_c(2940)^+$ as an $S-$wave $ND^*$ state with $I=0$ and $J^P=3/2^-$. Further information on the $ND$ and $ND^*$ interactions in the (unbound) scattering kinematics are obtained from the corresponding $S$-wave phase shifts. The $N\bar{B}$ and $N\bar{B}^*$ systems are also investigated within the present two models and some $S-$wave bound states with binding energies in the range of $1-60$ MeV are predicted in these systems: six (in total) within the extended chiral SU(3) quark model and, four, within the chiral SU(3) quark model.
- Open Access
Towards the Minimal Spectrum of Excited Baryons
In the light baryon sector resonances can be broad and overlapping and are in most cases not directly visible in the cross section data. Automatized model selection techniques that introduce penalties for resonances can be used to determine the minimally needed set of resonances to describe the data. Several possible penalization schemes are compared. As an application we perform a blindfold identification of hyperon resonances in the $\bar{K} N \to K \Xi$ reaction based on the Least Absolute Shrinkage and Selection Operator (LASSO) in combination with the Bayesian Information Criterion (BIC). We find ten resonances --- out of the 21 above-threshold hyperon resonances with spin $J\le 7/2$ listed by the Particle Data Group. In traditional analyses, it is practically impossible to test the relevance of all resonances and their combinations that may potentially contribute to the reaction. By contrast, the present method proves capable of determining the relevant resonances among a large pool of candidates.Open AccessTowards the Minimal Spectrum of Excited Baryons
In the light baryon sector resonances can be broad and overlapping and are in most cases not directly visible in the cross section data. Automatized model selection techniques that introduce penalties for resonances can be used to determine the minimally needed set of resonances to describe the data. Several possible penalization schemes are compared. As an application we perform a blindfold identification of hyperon resonances in the $\bar{K} N \to K \Xi$ reaction based on the Least Absolute Shrinkage and Selection Operator (LASSO) in combination with the Bayesian Information Criterion (BIC). We find ten resonances --- out of the 21 above-threshold hyperon resonances with spin $J\le 7/2$ listed by the Particle Data Group. In traditional analyses, it is practically impossible to test the relevance of all resonances and their combinations that may potentially contribute to the reaction. By contrast, the present method proves capable of determining the relevant resonances among a large pool of candidates.