Modern Nuclear Force Predictions for the α Particle

We present new calculations of the α particle which are based on the most modern nucleon-nucleon interactions alone and combined with the Tucson-Melbourne or the Urbana IX three-nucleon interaction. Results for the binding energies and some properties of the wave function are given. On that phenomenological level little room is left for the action of a possible four-nucleon force

Search for Three-Nucleon Force Effects in Two-Body Photodisintegration of 3He(3H) and in the Time Reversed Proton-Deuteron Radiative Capture Process

Faddeev calculations have been performed for nucleon-deuteron photodisintegration of 3He(3H) and proton-deuteron radiative capture. The bulk of the results is based on the AV18 nucleon-nucleon force and the Urbana IX three-nucleon force together with explicit exchange currents or applying the Siegert approach. Three-nucleon force effects are predicted for both processes and supported by most of the data.Comment: 21 pages, 8 figures, modified version with changed figures, conclusions unchanged, to appear in Phys.Rev.

The Hypernuclei Λ4He and Λ4H: Challenges for Modern Hyperon-Nucleon Forces

The hypernuclei Λ4He and Λ4H provide important information on the hyperon-nucleon interaction. We present accurate Faddeev-Yakubovsky calculations for the Λ separation energies of the 0+ ground and the 1+ excited states based on the Nijmegen SC YN interactions. We explicitly take the Σ admixture into account. Mass differences of the baryons and the charge dependence of the interaction are considered. The results show that the Nijmegen models cannot predict all separation energies simultaneously hinting to failures of the current interaction models. It is pointed out that the differences of the Λ separation energies of Λ4He and Λ4H are interesting observables to probe the YN interaction models

Lorentz boosted NN potential for few-body systems: Application to the three-nucleon bound state

A Lorentz boosted two-nucleon potential is introduced in the context of equal time relativistic quantum mechanics. The dynamical input for the boosted nucleon-nucleon (NN) potential is based on realistic NN potentials, which by a suitable scaling of the momenta are transformed into NN potentials belonging to a relativistic two-nucleon Schrödinger equation in the c.m. system. This resulting Lorentz boosted potential is consistent with a previously introduced boosted two-body t matrix. It is applied in relativistic Faddeev equations for the three-nucleon bound state to calculate the 3H binding energy. Like in previous calculations the boost effects for the two-body subsystems are repulsive and lower the binding energy

A new way to perform partial wave decompositions of few-nucleon forces

We formulate a general and exact method of partial wave decomposition (PWD) of any nucleon-nucleon (NN) potential and any three-nucleon (3N) force. The approach allows one to efficiently use symbolic algebra software to generate the interaction dependent part of the program code calculating the interaction. We demonstrate the feasibility of this approach for the one-boson exchange BonnB potential, a recent nucleon-nucleon chiral force and the chiral two-pion-exchange three-nucleon force. In all cases very good agreement between the new and the traditional PWD is found. The automated PWD offered by the new approach is of the utmost importance in view of future applications of numerous chiral N3LO contributions to the 3N force in three nucleon calculations.Comment: 10 pages, 6 figures (24 eps files

Low-momentum nucleon-nucleon interaction and its application to few-nucleon systems

Low-momentum nucleon-nucleon interactions are derived within the framework of a unitary-transformationtheory, starting with realistic nucleon-nucleon interactions. A cutoff momentum L is introduced to specify aborder between the low- and high-momentum spaces. By Faddeev-Yakubovsky calculations the lowmomentuminteractions are investigated with respect to the dependence of ground-state energies of 3H and 4Heon the parameter L. It is found that we need the momentum cutoff parameter Lù5 fm−1 in order to reproducesatisfactorily the exact values of the binding energies for 3H and 4He. The calculation with L=2 fm−1 recommendedby Bogner et al. leads to considerable overbinding at least for few-nucleon systems

Effective Interactions for the Three-Body Problem

The three-body energy-dependent effective interaction given by the Bloch-Horowitz (BH) equation is evaluated for various shell-model oscillator spaces. The results are applied to the test case of the three-body problem (triton and He3), where it is shown that the interaction reproduces the exact binding energy, regardless of the parameterization (number of oscillator quanta or value of the oscillator parameter b) of the low-energy included space. We demonstrate a non-perturbative technique for summing the excluded-space three-body ladder diagrams, but also show that accurate results can be obtained perturbatively by iterating the two-body ladders. We examine the evolution of the effective two-body and induced three-body terms as b and the size of the included space Lambda are varied, including the case of a single included shell, Lambda hw=0 hw. For typical ranges of b, the induced effective three-body interaction, essential for giving the exact three-body binding, is found to contribute ~10% to the binding energy.Comment: 19 pages, 9 figures, submitted to PR

Sensitivity studies for extraction of GEn from inclusive and semi-inclusive electron scattering on polarized 3He

The processes 3He→(e→,e′) and 3He→(e→,e′n) are theoretically analyzed with the aim to search for sensitivities in the electric form factor of the neutron, GEn. Faddeev calculations based on the high-precision NN force AV18 and using consistent mesonic exchange currents are employed. While the inclusive process is too insensitive, the semiexclusive one appears promising

Low-momentum nucleon-nucleon interaction and its application to few-nucleon systems

Low-momentum nucleon-nucleon interactions are derived within the framework of a unitary-transformation theory, starting with realistic nucleon-nucleon interactions. A cutoff momentum L is introduced to specify a border between the low- and high-momentum spaces. By Faddeev-Yakubovsky calculations the lowmomentum interactions are investigated with respect to the dependence of ground-state energies of 3H and 4He on the parameter L. It is found that we need the momentum cutoff parameter Lù5 fm−1 in order to reproduce satisfactorily the exact values of the binding energies for 3H and 4He. The calculation with L=2 fm−1 recommended by Bogner et al. leads to considerable overbinding at least for few-nucleon systems