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The NN\ensuremath{\rightarrow}N\ensuremath{\Delta} reaction is investigated within the coupled \ensuremath{\pi}NN-NN theory. The model predictions for the differential cross section, production asymmetry, and spin-correlation parameters are compared with the Argonne data at ${\mathit{T}}_{\mathit{N}}^{\mathrm{lab}}$=0.57, 0.81, and 1.01 GeV. Short-range effects are introduced through the \ensuremath{\rho}-exchange contribution. The overall quality of the results is satisfactory, except for the triplet part of the production asymmetry at the two highest energies. The role of the $^{3}$${\mathit{F}}_{3}$${\ensuremath{\rightarrow}}^{5}$${\mathit{P}}_{3}$ amplitude in this problem is assessed.

The \ensuremath{\pi}NN system is studied with two-term potentials for the \ensuremath{\pi}N interaction in the ${\mathit{P}}_{33}$ and ${\mathit{P}}_{11}$ channels. Such model systematics as the difference in the dominant \ensuremath{\pi}N ${\mathit{P}}_{33}$ input, the effect of the so-called backward propagating pion, the choice of the relative momenta (magic vectors) at the isobar vertices, etc., are investigated. The results in the \ensuremath{\pi}d-\ensuremath{\pi}d, \ensuremath{\pi}d-NN, and NN-NN reactions at intermediate energies are compared with the available experimental data. The overall quality of the predictions by the present approach is roughly comparable to that based upon the one-term ${\mathit{P}}_{33}$ isobar model supplemented by an appropriate ad hoc off-shell modification, but with a significant improvement in the description of the \ensuremath{\pi}d-NN asymmetry ${\mathit{A}}_{\mathit{y}0}$.

Results of recent theoretical studies on the electromagnetic form factors of strange baryons and kaons are embodied in a strangeness electromagnetic production model based on an effective Lagrangian approach. The sensitivity of different observables that are the subject of current or planned measurements at JLAB, are investigated with respect to the phenomenological ingredients of the model.

Previous approaches to the photo- and electro-production of strangeness on the proton, based upon effective Lagrangian, is extended to incorporate the so called off-shell effects (OSE) required while dealing with spin ⩾3/2 baryonic resonances. Results for K+ Λ channels are presented.

A formalism, based on an isobaric approach using Feynman diagrammatic techniques, which includes the nucleonic (spin \ensuremath{\le} 5/2), hyperonic (spin 1/2), and kaonic resonances, is developed. Using this formalism, a thorough investigation of the following electromagnetic strangeness processes, for which experimental results are available, is performed: \ensuremath{\gamma}p\ensuremath{\rightarrow}${\mathit{K}}^{+}$\ensuremath{\Lambda}, ${\mathit{K}}^{+}$${\mathrm{\ensuremath{\Sigma}}}^{0}$, ${\mathit{K}}^{0}$${\mathrm{\ensuremath{\Sigma}}}^{+}$, for ${\mathit{E}}_{\ensuremath{\gamma}}^{\mathrm{lab}}$\ensuremath{\le} 2.1 GeV, ep\ensuremath{\rightarrow}${\mathit{e}}^{\ensuremath{'}}$${\mathit{K}}^{+}$\ensuremath{\Lambda}, ${\mathit{e}}^{\ensuremath{'}}$${\mathit{K}}^{+}$${\mathrm{\ensuremath{\Sigma}}}^{0}$, and ${\mathit{K}}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\Lambda},\ensuremath{\gamma}${\mathrm{\ensuremath{\Sigma}}}^{0}$. A reaction mechanism, describing well enough the data, is found to include a reasonable number of baryonic resonances among a very large number of potential candidates. The extracted main kaon-hyperon-nucleon coupling constants are in good agreement with values predicted using SU(3) symmetry. The main findings of this model are compared with the results of other recent phenomenological studies. Predictions for the upcoming photoproduction polarization and electroproduction observables are presented, and their sensitivity to the phenomenological models ingredients are emphasized. \textcopyright{} 1996 The American Physical Society.

Starting from an appropriate low energy model, we investigate the role played by spin‐3/2 nucleonic resonances. A new model is obtained giving good agreement with data up to 2.1 GeV and satisfying SU(3) constraints on the main coupling constants.

A formalism, based on an isobaric approach, via Feynman diagrammatic technique, including the nucleonic (spin ≤ 5/2), hyperonic (spin 1/2) and kaonic resonances is developed. Using this formalism, a thorough investigation of all the electromagnetic strangeness processes, for which experimental results are available, is performed and satisfactory agreement with the data is obtained. The reaction mechanism is found to include a reasonable number of baryonic resonances, with the extracted main kaon-hyperon-nucleon coupling constants in agreement with the SU(3)-symmetry predictions. The sensitivity of this model to the form factors of the relevant hadrons is emphasized.

Investigations in progress on the associated strangeness photo‐ and electroproduction of the proton in the few GeV region and the negative kaon radiative capture are reported, and results for the K+∑0 channel are presented.

This chapter focuses on Coulomb energy of 3 He. The AGS quasiparticle method provides a way to include the Coulomb interaction in the three-nucleon system, especially, as demonstrated by Alessandrini and Zankel, if only two charged nucleons are present in the three-body system. The method takes into account the Coulomb force exactly, and so the usual Coulomb singularity problem arises. As there is still no manageable exact treatment of the Coulomb many-body system available, the Coulomb singularity is circumvented by using a Yukawa type cutoff. Considering the small internucleon distances in the three-nucleon bound state, it seems to be plausible that the long-range Coulomb singularity rather weakly influences the three-nucleon binding energy. Switching off all Coulomb contributions in the 3 He, assuming charge symmetry of the nuclear forces, a model is obtained for the triton. The binding energy difference of 3 H and 3 He is then the Coulomb energy ( E C ) of He. The chapter illustrates the effective potential of 3 He.

We have investigated the Phillips' plot with different types of nonlocal separable interactions (up to rank 6) in the3S1-3D1 channel. We have then included all theP-wave contributions with rank-one interactions. The effect appears to be weak on the triton binding energy but nonnegligible on the doublet scattering length.

We show the great sensitivity of the πd elastic-scattering observables to the details of the deuteron wave function. At 142 MeV and 256 MeV we find that the differential cross-section at θc.m.=180° depends linearly upon the quantityA(q2), which is the most important part of the deuteron electromagnetic form factor. A similar behaviour appears for the tensor polarizationt20(180°) at 142 MeV. Our results are compared with existing experimental data at backward angles.

The exact-finite-range coupled-reaction channel formalism in heavy-ion transfer reactions is derived as a generalization of the Cokeret al. work. The transition amplitude involving possible excitations in the entrance and exit channels is then given. Two special cases have been considered: the zero-range and the\(\overline K \)-approximations.

We give here a brief description of the present status in the angular momentum reduction in the three-body problem. First theOmnes’ symmetrical method is restated. We have then presented three unsymmetrical methods derived from theAhmadzadeh andTjon’s work, the first one, due toGrubman, uses a particular determination of the body-fixed axis. In the second method we use the well-known expansion of a spherical harmonic the argument of which is a sum of two vectors. The third method starts from theFaddeev—Lovelace formalism and also uses the above expansion of a spherical harmonic. A comparison between these methods is made on the particular (n−d) case.

The coupled πNN-NN theory is examined in its dominant πN P33 (or Δ) input by a direct calculation of the NN → NΔ observables which are then compared with the recent data on pp → Δ+ + n extracted from the pp → π+ pn reaction at medium energies.