As a first step to analyze the electromagnetic meson production reactions in the nucleon resonance region, the parameters of the hadronic interactions of a dynamical coupled-channel model, developed in Physics Reports 439, 193 (2007), are determined by fitting the πN scattering data. The channels included in the calculations are πN , ηN and ππN which has π∆, ρN , and σN resonant components. The non-resonant meson-baryon interactions of the model are derived from a set of Lagrangians by using a unitary transformation method. One or two bare excited nucleon states in each of S, P , D, and F partial waves are included to generate the resonant amplitudes in the fits. The parameters of the model are first determined by fitting as much as possible the empirical πN elastic scattering amplitudes of SAID up to 2 GeV. We then refine and confirm the resulting parameters by directly comparing the predicted differential cross section and target polarization asymmetry with the original data of the elastic π ± p → π ± p and charge-exchange π − p → π 0 n processes. The predicted total cross sections of πN reactions and πN → ηN reactions are also in good agreement with the data. Applications of the constructed model in analyzing the electromagnetic meson production data as well as the future developments are discussed.

The electromagnetic pion production reactions are investigated within the dynamical coupledchannels model developed in Physics Reports, 439, 193 (2007). The meson-baryon channels included in this study are γN , πN , ηN , and the π∆, ρN and σN resonant components of the ππN channel. With the hadronic parameters of the model determined in a recent study of πN scattering, we show that the pion photoproduction data up to the second resonance region can be described to a very large extent by only adjusting the bare γN → N * helicity amplitudes, while the non-resonant electromagnetic couplings are taken from previous works. It is found that the coupled-channels effects can contribute about 30 -40 % of the production cross sections in the ∆ (1232) resonance region, and can drastically change the magnitude and shape of the cross sections in the second resonance region. The importance of the off-shell effects in a dynamical approach is also demonstrated. The meson cloud effects as well as the coupled-channels contributions to the γN → N * form factors are found to be mainly in the low Q 2 region. For the magnetic M1 γN → ∆ (1232) form factor, the results are close to that of the Sato-Lee Model. Necessary improvements to the model and future developments are discussed.

Within the dynamical model of Refs. [Phys. Rev. C 54, 2660 (1996); 63, 055201 (2001)], we perform an analysis of recent data of pion electroproduction reactions at energies near the (1232) resonance. We discuss possible interpretations of the extracted bare and dressed γ N → form factors in terms of relativistic constituent quark models and lattice quantum chromodynamics calculations. Possible future developments are discussed.

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.

A dynamical coupled-channel formalism for processes πN → KY and γN → KY is presented which provides a comprehensive investigation of recent data on the γp → K + Λ reaction. The nonresonant interactions within the subspace KY ⊕ πN are derived from effective Lagrangians, using a unitary transformation method. The calculations of photoproduction amplitudes are simplified by casting the coupled-channel equations into a form such that the empirical γN → πN amplitudes are input and only the parameters associated with the KY channel are determined by performing χ 2 -fits to all of the available data for π − p → K • Λ, K • Σ • and γp → K + Λ. Good agreement between our models and those data are obtained. In the fits to πN → KY channels, most of the parameters are constrained within ±20% of the values given by the Particle Data Group and/or quark model predictions, while for γp → K + Λ parameters, ranges compatible with broken SU (6)⊗ O(3) symmetry are imposed. The main reaction mechanisms in K + Λ photoproduction are singled out and issues related to newly suggested resonances S 11 , P 13 , and D 13 are studied. Results illustrating the importance of using a coupled-channel treatment are reported. Meson cloud effects on the γN → N * transitions are also discussed.

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We consider a Bose-Einstein condensate in a double-well potential undergoing a dynamical transition from the regime of Josephson oscillations to the regime of self-trapping. We analyze the statistical properties of the ground state (or the highest excited state) of the Hamiltonian in these two regimes for attractive (repulsive) interactions. We demonstrate that it is impossible to describe the transition within the mean-field theory. In contrast, the transition proceeds through a strongly correlated delocalized state, with large quantum fluctuations, and spontaneous breaking of the symmetry.

We have performed a dynamical coupled-channels analysis of available p(e, e ′ π)N data in the region of W ≤ 1.6 GeV and Q 2 ≤ 1.45 (GeV/c) 2 . The channels included are γ * N , πN , ηN , and ππN which has π∆, ρN , and σN components. With the hadronic parameters of the model determined in our previous investigations of πN → πN, ππN reactions, we have found that the available data in the considered W ≤ 1.6 GeV region can be fitted well by only adjusting the bare γ * N → N * helicity amplitudes for the lowest N * states in P 33 , P 11 , S 11 and D 13 partial waves. The sensitivity of the resulting parameters to the amount of data included in the analysis is investigated. The importance of coupled-channels effect on the p(e, e ′ π)N cross sections is demonstrated. The meson cloud effect, as required by the unitarity conditions, on the γ * N → N * form factors are also examined. Necessary future developments, both experimentally and theoretically, are discussed.