The three-nucleon (3N) Faddeev equation is solved in a Poincaré-invariant model of the three-nucleon system. Two-body interactions are generated so that when they are added to the two-nucleon invariant mass operator (rest energy) the two-nucleon S-matrix is identical to the non-relativistic S-matrix with a CD Bonn interaction. Cluster properties of the three-nucleon S-matrix determine how these two-nucleon interactions are embedded in the three-nucleon mass operator. Differences in the predictions of the relativistic and corresponding non-relativistic models for elastic and breakup processes are investigated. Of special interest are the lowering of the Ay maximum in elastic nucleon-deuteron (Nd) scattering below ≈25?MeV caused by the Wigner spin rotations and the significant changes of the breakup cross sections in certain regions of the phase space. 相似文献
Polarization observables in low-energy proton-deuteron radiative capture have been calculated using the Bonn-B nucleon-nucleon
potential. Their sensitivity to the changes of the nucleon-nucleon force components has been studied. Modifications of these forces, which drastically diminished the permanent
discrepancy between the data and theory for the vector-analyzing power in low-energy nucleon-deuteron elastic scattering,
have only small effects on the pd capture observables.
Received May 26, 1999; accepted for publication June 30, 1999 相似文献
We develop an approach for calculating matrix elements of meson-exchange current operators between three-nucleon basis states
in -coupling and a three-nucleon bound state. The contributions generated by π- and ρ-exchanges are included into the consideration.
The matrix elements are expressed in terms of multiple integrals in momentum space. We apply a technique of partial-wave decompositions
and carry out some angular integrations in closed form. Different representations appropriate for numerical calculations are
derived for the matrix elements of interest. The momentum dependences of the matrix elements are studied and benchmark results
are presented. The approach developed is of interest for investigations of deuteron-proton radiative capture and 3He photo- and electrodisintegration when the interactions in the initial or final states are taken into account by solving
the Faddeev equations.
Received April 2, 1999; accepted for publication December 30, 1999 相似文献
Based on the preformed cluster model (PCM), we have extended our earlier study on cluster decays of heavy parent nuclei to analyze the effects of different nuclear proximity potentials in the ground-state clusterization of superheavy nuclei with Z = 113, 115 and 117. In order to look for the possible role of deformations, calculations are performed for spherical as well as β2-deformed choices of fragmentation. The relevance of “hot compact” over “cold elongated” configurations due to orientations is also explored, in addition to the role of Q value and angular momentum ℓ effects. As the PCM is based on collective clusterization picture, the preformation and penetration probabilities get modified considerably, and hence do so the decay constants and half-lives of the clusters, with the use of different nuclear proximity potentials. The comparative importance of nuclear proximity potentials Prox-1977 and Prox-2000 is analyzed and the calculated decay half-lives in the framework of PCM are compared with the recent predictions of the analytical super-asymmetric fission model (ASAFM). The possible role of shell corrections is also investigated for understanding the dynamics of heavy particle radioactivity. Finally, the potential energy surfaces are compared for different proton and neutron magic numbers in superheavy mass region.
Cross sections and vector-analyzing powers for four unspecific configurations of the 2H(p,pp)n breakup reaction at Elabp = 65MeV were measured in a kinematically complete experiment. Measured observables are compared with rigorous Faddeev calculations
using four realistic charge-dependent interaction models, the CD Bonn, Argonne v18, Nijmegen I, and Nijmegen II potentials with or without inclusion of the Tucson-Melbourne three-nucleon force. Coulomb effects
are completely omitted. A satisfactory agreement between theory and experiment has been found. There exist, however, some
discrepancies between measured and calculated analyzing-power distributions in certain kinematical regions. The effects of
the Tucson-Melbourne three-body force are either negligible or slightly increasing the disagreement.
Received May 12, 1999; revised March 3, 2000; accepted for publication April 26, 2000 相似文献
The electron-induced processes on 3He are analyzed using the Faddeev formalism with modern nucleon-nucleon and three-nucleon forces as well as exchange currents. The kinematical region is restricted to a mostly nonrelativistic one where the three-nucleon c.m. energy is below the pion production threshold and the three-momentum of the virtual photon is sufficiently below the nucleon mass. Comparisons with available data are shown and cases of agreement and disagreement are found. It is argued that new and precise data are needed to systematically check the present-day dynamical ingredients.Received: 6 February 2004, Published online: 17 August 2004PACS:
21.45. + v Few-body systems - 21.10.-k Properties of nuclei; nuclear energy levels - 25.10. + s Nuclear reactions involving few-nucleon systems - 25.20.-x Photonuclear reactions 相似文献
We solved the Faddeev equation in a Poincaré invariant model of the three-nucleon system. Two-body interactions are generated so that when they are added to the two-nucleon invariant mass operator (rest energy) the two-nucleon S matrix is identical to the experimental S matrix modeled with a given nucleon?Cnucleon interaction. Cluster properties of the three-nucleon S-matrix determine how these two-nucleon interactions are embedded in the three-nucleon mass operator. Differences in the predictions of the relativistic and corresponding non-relativistic models for elastic and breakup processes are investigated. Of special interest are effects of relativity on the elastic scattering angular distribution and total cross sections, the lowering of the Ay maximum in elastic nucleon-deuteron (Nd) scattering below ??25?MeV caused by the Wigner spin rotations and the significant changes of the breakup cross sections in certain regions of the phase-space. 相似文献
A recently developed formulation for a direct treatment of the equations for two- and three-nucleon bound states as set of
coupled equations of scalar functions depending only on vector momenta is extended to three-nucleon scattering. Starting from
the spin-momentum dependence occurring as scalar products in two- and three-nucleon forces together with other scalar functions,
we present the Faddeev multiple scattering series in which order by order the spin degrees can be treated analytically leading
to 3D integrations over scalar functions depending on momentum vectors only. Such formulation is especially important in view
of awaiting extension of 3N Faddeev calculations to projectile energies above the pion production threshold and applications
of chiral perturbation theory 3N forces, which are to be most efficiently treated directly in such three-dimensional formulation
without having to expand these forces into a partial-wave basis. 相似文献
The direct treatment of the Faddeev equation for the three-boson system in 3 dimensions is generalized to nucleons. The one Faddeev equation for identical bosons is replaced by a strictly finite set of coupled equations for scalar functions which depend only on 3 variables. The spin-momentum dependence occurring as scalar products in 2N and 3N forces accompanied by scalar functions is supplemented by a corresponding expansion of the Faddeev amplitudes. After removing the spin degrees of freedom by suitable operations only scalar expressions depending on momenta remain. The corresponding steps are performed for the deuteron leading to two coupled equations. 相似文献