[en] Basic ideas of chiral perturbation theory applied to nuclear forces are sketched. Applications in the two- and three-nucleon systems are shown which support the hope to gain the Hamiltonian valid in low energy nuclear physics and which is linked to QCD. The relation to the one-boson-exchange models is mentioned

[en] We report on recent progress achieved in calculating various few-nucleon low-energy observables from effective field theory. Our discussion includes scattering and bound states in the 2N, 3N and 4N systems and isospin violating effects in the 2N system. We also establish a link between the nucleon-nucleon potential derived in chiral effective field theory and various modern high-precision potentials

[en] Polarization correlation coefficients have been measured at RIKEN for the ³H vector e(d vector, p)⁴He reaction at intermediate energies (E_d = 270 MeV). We propose a model for the (d vector, p) reaction mechanism using the pd elastic scattering amplitude, which is rigorously determined with a Faddeev calculation and using modern NN forces. Our theoretical predictions for the deuteron polarization observables A_y, A_yy, A_xx and A_xz at E_d = 140, 200 and 270 MeV are given. The A_y observables agree qualitatively in shape with the new experimental data for the reaction ³He(d vector, p)⁴He. (author)

[en] A spin-isospin dependent Three-Dimensional formalism based on the momentum vectors for the four-nucleon bound state is presented. The four-nucleon Yakubovsky equations with two- and three-nucleon interactions are formulated as a function of the vector Jacobi momenta. Our formalism, according to the number of spin-isospin states that one takes into account, leads to only a strictly finite number of the coupled three dimensional integral equations to be solved. The evaluation of the transition and permutation operators as well as the coordinate transformations due to considering the continuous angle variables instead of the discrete angular momentum quantum numbers are less complicated in comparison with partial wave representation. With respect to partial wave the present formalism with the smaller number of equations leads to higher dimensionality of the integral equations. We have concluded that three dimensional formalism is less cumbersome for considering the three-nucleon forces. (author)

[en] A method for solving few-body scattering equations is proposed and examined. The solution of the scattering equations at complex energies is analytically continued to get scattering t-matrix with real positive energy. Numerical examples document that the method works well for two-nucleon scattering and three-nucleon scattering, if the set of complex energies is properly chosen. (author)

[en] We have investigated the possible existence of a quasi-bound state for the Σ-Σ-α system in the framework of Faddeev calculations. We are particularly interested in the state of total iso-spin T=2, since for an inert α particle there is no strong conversion to Ξ-N-α or Λ-Λ-α possible. A Σ-α optical potential based on Nijmegen model D and original Σ-Σ interactions of the series of Nijmegen potentials NSC97 as well a simulated Gaussian type versions thereof are used. Our investigation of the Σ-Σ-α system leads to a quasi bound state where, depending on the potential parameters, the energy ranges between -1.4 and -2.4 MeV and the level width is less than 0.4 MeV. (author)

[en] Some recent developments in the description of nuclear forces and few-nucleon dynamics derived from chiral effective field theory are reviewed. (author)

[en] In the modern description of nuclear forces based on chiral effective field theory, four-nucleon operators with unknown coupling constants appear. These couplings can be fixed by a fit to the low partial waves of nucleon-nucleon scattering. We show that the so-determined numerical values have a remarkable similarity to values extracted from phenomenological one-boson-exchange models in a low momentum expansion. We also extract these values from various modern high accuracy nucleon-nucleon potentials and find again the same similarity. This paves the way for estimating the low-energy constants of operators with more nucleon fields and/or external probes

[en] A measurement of the analyzing powers for the 1H((rvec d),pp)n breakup reaction at 130 MeV polarized deuteron beam energy was carried out at KVI Groningen. The experimental setup covered a large fraction of the phase space. Obtained tensor analyzing powers T22 for selected kinematical configurations have been compared to theoretical predictions based on various approaches: the rigorous Faddeev calculations using the realistic nucleon--nucleon potentials with and without three nucleon force (3NF) models, predictions of the chiral perturbation theory, and coupled channel calculations with the explicit Δ degrees of freedom. In the presented configurations the results of all predictions are very close to one another and there are no significant 3NF influences. Not all of the data can be satisfactory reproduced by the theoretical calculations.

[en] Using the complex energy method, the problem of nucleon-deuteron scattering is solved with a simple three-body force having a separable form. Our results are compared with the results of modern direct two-variable calculations and a good agreement is found. This forms a firm base for other applications of the complex energy method. (author)