The nucleon resonances are investigated within a dynamical coupled-channels model of πN and γN reactions up to the invariant mass W = 2 GeV. The meson-baryon (M B) channels included in the calculations are M B = πN , ηN , KΛ, KΣ, and ππN that has π∆, ρN , and σN resonant components. From the extracted residues, we have determined the N * → πN, γN, ηN, KΛ, KΣ transition amplitudes at resonance poles. We compare the resonance pole positions from our analysis with those given by the Particle Data Group and the recent coupled-channels analyses by the Jülich and Bonn-Gatchina groups. Four results agree well only for the first N * in each spin-parity-isospin (J P , I) channel. For higher mass states, the number of states and their resonance positions from four results do not agree well. We discuss the possible sources of the discrepancies and the need of additional data from new hadron facilities such as J-PARC.

We show that two almost degenerate poles near the piDelta threshold and the next higher mass pole in the P11 partial wave of piN scattering evolve from a single bare state through its coupling with piN, etaN, and pipiN reaction channels. This finding provides new information on understanding the dynamical origins of the Roper N{*}(1440) and N{*}(1710) resonances listed by Particle Data Group. Our results for the resonance poles in other piN partial waves are also presented.

We study the resonance energy of the strange dibaryons using two models with the energy-independent and energy-dependent potentials for the s-waveKN 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-bodyKN -πΣ amplitudes in I = 0 channel, i.e., the model with energy-independent (energy-dependent) potential predicts one (two) resonance pole in the Λ(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 thē KN N , and the other is the resonance of the πY N with large width. An investigation of the binding energy of the strange dibaryons will make a significant contribution to clarify resonance structure of s-waveKN -πΣ around the Λ(1405) region. Subject Index: 232Since the deeply bound kaonic nuclear states were predicted, 1) few-nucleon systems with a kaon have attracted increasing interest. Among the deeply bound kaonic states, the resonances in theKN N -πY N (Y = Σ, Λ) system (strange dibaryons) are actively investigated recently, since the three-hadron dynamics can be theoretically handled by the well-established Faddeev equations. Using the coupled-channel Faddeev equations, two of the authors 2), 3) and Shevchenko et al. 4) studied the possible existence and the energy of the strange dibaryons. It has been found in these studies that off-shell behaviors of the two-bodyKN -πΣ amplitudes in I = 0 channel, which involve the Λ(1405) resonance, strongly affect the determination of the energy of the strange dibaryons.In Refs. 2) and 3), the energy of the strange dibaryons is evaluated by employing the following energy-independent potential for theKN -πY subsystem (we refer to this potential model as 'E-indep' throughout this letter):Here indices i, j represent the meson-baryon channel in isospin basis; m i (p i ) is the meson mass (the relative momentum in the center of mass frame) of the channel i; C ij = λ ij / 32π 2 F 2 π ω i (p i )ω j (p j ) with ω i (p i ) = m 2 i + p 2 i and F π = 92.4

Abstract.A new generation of complete experiments is focused on a high precision extraction of pseudoscalar meson photo-production amplitudes. Here, we review the development of the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single, double and triple-polarization terms involving 16 spin-dependent observables. We examine the different conventions that have been used by different authors, and we present expressions that allow the direct numerical calculation of any pseudoscalar meson photo-production observables with arbitrary spin projections from the ChewGoldberger-Low-Nambu (CGLN) amplitudes. We use this numerical tool to clarify apparent sign differences that exist in the literature, in particular with the definitions of six double-polarization observables. We also present analytic expressions that determine the recoil baryon polarization, together with examples of their potential use with quasi-4π detectors to deduce observables. As an illustration of the use of the consistent machinery presented in this review, we carry out a multipole analysis of the γp → K + Λ reaction and examine the impact of recently published polarization measurements. When combining data from different experiments, we utilize the Fierz identities to fit a consistent set of scales. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow χ 2 valley pitted with a very large number of local minima. This results in broad bands of multipole solutions that are experimentally indistinguishable. While these bands have been noticeably narrowed by the inclusion of new polarization measurements, many of the multipoles remain very poorly determined, even in sign, despite the inclusion of data on 8 different observables. We have compared multipoles from recent PWA codes with our model-independent solution bands, and found that such comparisons provide useful consistency tests which clarify model interpretations. The potential accuracy of amplitudes that could be extracted from measurements of all 16 polarization observables has been studied with mock data using the statistical variations that are expected from ongoing experiments. We conclude that, while a mathematical solution to the problem of determining an amplitude free of ambiguities may require 8 observables, as has been pointed out in the literature, experiments with realistically achievable uncertainties will require a significantly larger number.

A dynamical coupled-channels (DCC) model for neutrino-nucleon reactions in the resonance region is developed. Starting from the DCC model that we have previously developed through an analysis of πN, γN → πN, ηN, KΛ, KΣ reaction data for W ≤ 2.1 GeV, we extend the model of the vector current to Q 2 ≤ 3.0 (GeV/c) 2 by analyzing electron-induced reaction data for both proton and neutron targets. We derive axial-current matrix elements that are related to the πN interactions of the DCC model through the Partially Conserved Axial Current (PCAC) relation. Consequently, the interference pattern between resonant and non-resonant amplitudes is uniquely determined. We calculate cross sections for neutrino-induced meson productions, and compare them with available data. Our result for the single-pion production reasonably agrees with the data. We also make a comparison with the double-pion production data. Our model is the first DCC model that can give the double-pion production cross sections in the resonance region. We also make comparison of our result with other existing models to reveal an importance of testing the models in the light of PCAC and electron reaction data. The DCC model developed here will be a useful input for constructing a neutrino-nucleus reaction model and a neutrino event generator for analyses of neutrino experiments.