arXiv subjects
Publications and source records attributed to Hiroyuki Kamano.
We give an overview of recent progress in the spectroscopic study of nucleon resonances within the dynamical coupled-channels analysis of meson-production reactions. The important role of multichannel reaction dynamics in understanding various properties of nucleon resonances is emphasized.
Recent results on the study of light-quark baryons with the ANL-Osaka dynamical coupled-channels (DCC) approach are presented, which contain the N* and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the Lambda* and Sigma* spectroscopy via the analysis of K- p reactions. A recent application of our DCC approach to neutrino-nucleon reactions in the resonance region is also presented.
The intrinsic difficulties in extracting the hadron resonances from reaction data are illustrated by using several exactly soluble $ππ$ scattering models. The finite-volume Hamiltonian method is applied to predict spectra using two meson-exchange Hamiltonians of $πN$ reactions. Within a three-channel model with $πN$, $πΔ$ and $σN$ channels, we show the advantage of the finite-volume Hamiltonian method over the approach using the Lüscher formula to test Lattice QCD calculations aimed at predicting nucleon resonances. We discuss the necessary steps for using the ANL-Osaka eight-channel Hamiltonian to predict the spectra for testing the LQCD calculations for determining the excited nucleon states up to invariant mass $W= 2 $ GeV.
We report our recent effort for the extraction of resonance parameters (complex pole mass and residues etc.) associated with Lambda* and Sigma* hyperons. This was accomplished via a comprehensive partial-wave analysis of the data for K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi reactions from the thresholds up to W=2.1 GeV within a dynamical coupled-channels approach. The results suggest a possible existence of new narrow J^P=3/2^+ Λresonance with pole mass 1671^{+2}_{-8} -i(5^{+11}_{-2}) MeV, located close to the eta Lambda threshold. This resonance is found to be responsible for reproducing the data for K^-p --> eta Lambda differential cross sections near the threshold, and thus the data seem favor its existence. The extracted poles for J^P=1/2^- Lambda resonances below the barK N threshold, including Lambda(1405), are also presented.
We review our recent efforts for determining resonance parameters associated with light-quark baryons ($N^*$, $Δ^*$, $Λ^*$, $Σ^*$) through comprehensive analyses of various meson production reactions off the nucleon within the ANL-Osaka dynamical coupled-channels approach.
We analyze the current status of three P-wave baryon states $N(1710){1/ 2}^+$, $N(1900){3/2}^+$, and $Δ(1600){3/2}^+$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recommendations.
Motivated by an experimental proposal for the measurement of the pi N --> pi pi N reactions at J-PARC, we examine a potential impact of the pi N --> pi pi N cross section data on the determination of the resonance parameters of the high-mass N* states. For this purpose, we make use of the ANL-Osaka dynamical coupled-channels model, which has been developed recently by a combined analysis of the unpolarized as well as polarized observables of pion- and photon-induced pi N, eta N, K Lambda, and K Sigma production reactions off a proton target. We present predictions for the pi N --> pi pi N total cross sections and invariant mass distributions, and demonstrate that the pi N --> pi pi N differential cross section data can indeed be a crucial source of information for understanding N* --> pi Delta, rho N, sigma N --> pi pi N decay of the high-mass N* states.
We examine how the signature of the strange dibaryon resonances shows up in scattering amplitudes and observables of the three-body $\bar{K}NN$-$πY N (Y=Σ, Λ)$ system on the physical real energy axis. The so-called point method is applied to handle logarithmic singularities that appear in solving the Alt-Grassberger-Sandhas equations for the real scattering energies. By taking two different kinds of models for the two-body $\bar{K}N$-$πΣ$ subsystem, both of which reproduce the available data equally well but give quite a different resonance-pole structure for $Λ(1405)$, we also investigate whether the strange-dibaryon production reactions can be used for disentangling the nature of $Λ(1405)$.
We review a global analysis of meson production reactions off the nucleons by a collaboration at Excited Baryon Analysis Center of Jefferson Lab. The analysis is pursued with a dynamical coupled-channels approach, within which the dynamics of multi-channel reaction processes are taken into account in a fully consistent way with the two-body as well as three-body unitarity of the S-matrix. With this approach, new features of nucleon excitations are revealed as resonant particles originating from the non-trivial multi-channel reaction dynamics, which cannot be addressed by static hadron models where the nucleon excitations are treated as stable particles.
We examine how the signature of the strange-dibaryon resonances in the barKNN-piSigmaN system shows up in the scattering amplitude on the physical real energy axis within the framework of Alt-Grassberger-Sandhas (AGS) equations. The so-called point method is applied to handle the three-body unitarity cut in the amplitudes. We also discuss the possibility that the strange-dibaryon production reactions can be used for discriminating between existing models of the two-body barKN-piSigma system with Lambda(1405).
We present an alternative interpretation for the dynamical origin of the P11 nucleon resonances, which results from the dynamical coupled-channels analysis at Excited Baryon Analysis Center of Jefferson Lab. The results indicate the crucial role of the multichannel reaction dynamics in determining the N^* spectrum.
The scattering length and effective range of the piSigma channel are studied in order to characterize the strangeness S=-1 meson-baryon scattering and the Lambda(1405) resonance. We examine various off-shell dependence of the amplitude in dynamical chiral models to evaluate the threshold quantities with the constraint at the KbarN threshold. We find that the piSigma threshold parameters are important to the structure of the Lambda(1405) resonance and provide further constraints on the subthreshold extrapolation of the KbarN interaction.
We report the current status of exploring the dynamical aspect of the excited nucleon states through the comprehensive coupled-channels analysis of meson production reactions at the Excited Baryon Analysis Center of Jefferson Lab.
We present the current status of a combined and simultaneous analysis of meson production reactions based on a dynamical coupled-channels (DCC) model, which is conducted at Excited Baryon Analysis Center (EBAC) of Jefferson Lab.
We study the resonance energy of the strange dibaryons using two models with the energy-independent and energy-dependent potentials for the s-wave barKN interaction, both of which are derived by certain reductions from the leading order term of the effective chiral Lagrangian. These potential models produce rather different off-shell behaviors of the two-body barKN - piSigma amplitudes in I=0 channel, i.e., the model with energy-independent (energy-dependent) potential predicts one (two) resonance pole in the Lambda(1405) region, while they describe the available data equally well. We find that the energy-independent potential model predicts one resonance pole of the strange dibaryons, whereas the energy-dependent potential model predicts two resonance poles: one is the shallow quasi-bound state of the barKNN, and another is the resonance of the piYN with large width. An investigation of the binding energy of the strange dibaryons will make a significant contribution to clarify resonance structure of s-wave barKN - piSigma around the Lambda(1405) region.
The master formula approach to chiral symmetry breaking proposed by Yamagishi and Zahed is extended to the U_R(3)xU_L(3) group, in which effects of the U_A(1) anomaly and the flavor symmetry breaking m_u \not= m_d \not= m_s are properly contained. New identities for the gluon topological susceptibility and pi^0, eta, eta' -> gamma^(*) gamma^(*) decays are derived, which exactly embody the consequence from broken chiral symmetry in QCD without relying on any unphysical limit.
We present the dynamical origin of the P11 nucleon resonances resulting from a dynamical coupled-channels (DCC) analysis of meson production reactions off a nucleon target, which is conducted at Excited Baryon Analysis Center (EBAC) of Jefferson Lab. Two resonance poles are found in the energy region where the Roper resonance P11(1440) was identified. Furthermore, the two resonance poles and the next higher resonance pole corresponding to P11(1710) are found to originate from a single bare state.
We present an overview of a research program for the excited nucleon states in Excited Baryon Analysis Center (EBAC) at Jefferson Lab. Current status of our analysis of the meson production reactions based on the unitary dynamical coupled-channels model is summarized, and the N* pole positions extracted from the constructed scattering amplitudes are presented. Our plans for future developments are also discussed.