[en] The quantum relativistic field theory of hadron exchange has provided an excellent description of medium and long range forces (r>1/2μ^-1) for low energy nucleon-nucleon interactions (Esub(L)<350MeV). We demonstrate that the successful application of this approach can be extended to medium energies (350MeV< Esub(L)<1000MeV) after including the effect of the coupling of the nucleon-nucleon to nucleon-isobar channels

[en] As has already been discussed, nuclear potentials at small distances have many complications. Appreciable non-static effects may be expected at c stances less than half a meson Compton wavelength, due to many meson and strange particle intermediate states. This is reflected in the hard core, spin-orbit or other non-local contributions required in phenomenological potentials. Several years ago work by G. Breit, and by H. Feshbach and myself, showed that an alternative, simpler, description of the strong interaction region may be feasible. It was proposed that the large amount of energy inherent in the virtual states involved at small distances should make the interior wave function insensitive to the relative kinetic energy; that this internal region could therefore be replaced by an energy-independent boundary condition (only the logarithmic derivative of the wave function is required) at some boundary radius at the edge of the region of “ strong ” interaction. Outside this region the potential description would apply and some correspondence with the one and two meson predictions of meson theory could be sought. If the boundary radius is large enough a static potential might be adequate, simplifying the description. (author)

[en] A model which fits the nucleon-nucleon data for Esub(L)<=800 MeV using a field theoretical NN potential and one-pion exchange couplings to NΔ, ΔΔ and NN*(1440) isobars outside a boundary condition core puts many theoretical and phenomenological constraints on the core and short range transition potential parameters. Some consequences of the model for the deuteron are discussed. (Auth.)

[en] Quark structure of hadrons cannot be ignored in hadron-hadron interactions which already probe the region of asymptotic freedom at relatively low energies. But one cannot compute the full interaction directly with QCD because: (1) very high order processes enter at medium and small momentum transfer; (2) bag models approximate confinement, and (3) contain no theoretical information on longer range interactions of (unconfined) color singlet pairs. Our present understanding of nucleon-nucleon and nuclear data implies that nucleon degrees of freedom and hadronic field theory are adequate descriptions for r greater than or equal to 1 fm. The total potential fits np and pp data for laboratory energy E_L < 400 MeV. For higher energies the dynamic effects of production thresholds must be included. Work by Kloet and Silbar and by Lomon has shown that these can account for data up to E_L = 800 MeV, including the dibaryonic structures seen

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[en] The roles played by mesons in the electromagnetic form factors of the nucleon are explored using as a basis a model containing vector mesons with coupling to the continuum together with the asymptotic Q² behavior of perturbative QCD. Specifically, the vector dominance model (GKex) developed by E. L. Lomon is employed, as it is known to be very successful in representing the existing high-quality data published to date. An analysis is made of the experimental uncertainties present when the differences between the GKex model and the data are expanded in orthonormal basis functions. A main motivation for the present study is to provide insight into how the various ingredients in this model yield the measured behavior, including discussions of when dipole form factors are to be expected or not, of which mesons are the major contributors, for instance, at low Q² or large distances, and of what effects are predicted from coupling to the continuum. Such insights are first discussed in momentum space, followed by an analysis of how different and potentially useful information emerges when both the experimental and theoretical electric form factors are Fourier transformed to coordinate space. While these Fourier transforms should not be interpreted as ''charge distributions,'' nevertheless the roles played by the various mesons, especially those which are dominant at large or small distance scales, can be explored via such experiment-theory comparisons.