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

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

Proton-proton scattering without Coulomb force renormalization

We demonstrate numerically that proton-proton (pp) scattering observables can be determined directly by standard short range methods using a screened pp Coulomb force without renormalization. In examples the appropriate screening radii are given. We also numerically investigate solutions of the 3-dimensional Lippmann-Schwinger (LS) equation for a screened Coulomb potential alone in the limit of large screening radii and confirm analytically predicted properties for off-shell, half-shell and on-shell Coulomb t-matrices. These 3-dimensional solutions will form a basis for a novel approach to include the pp Coulomb interaction into the 3N Faddeev framework.Comment: 22 pages, 13 eps figure

A novel treatment of the proton-proton Coulomb force in elastic proton-deuteron Faddeev calculations

We propose a novel approach to incorporate the proton-proton (pp) Coulomb force into the three-nucleon (3N) Faddeev calculations. The main new ingredient is a 3-dimensional screened pp Coulomb t-matrix obtained by a numerical solution of the 3-dimensional Lippmann-Schwinger (LS) equation. We demonstrate numerically and provide analytical insight that the elastic proton-deuteron (pd) observables can be determined directly from the resulting on shell 3N amplitude increasing the screening radius. The screening limit exists without the need of renormalisation not only for observables but for the elastic pd amplitude itself.Comment: 33 pages, 4 eps figures. New figure with a description in the Section V and minor text changes have been added. The physical conclusions remain unchange

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

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

Evidence for a three-nucleon-force effect in proton-deuteron elastic scattering

Developments in spin-polarized internal targets for storage rings have permitted measurements of 197 MeV polarized protons scattering from vector polarized deuterons. This work presents measurements of the polarization observables A_y, iT_11, and C_y,y in proton-deuteron elastic scattering. When compared to calculations with and without three-nucleon forces, the measurements indicate that three-nucleon forces make a significant contribution to the observables. This work indicates that three-body forces derived from static nuclear properties appear to be crucial to the description of dynamical properties.Comment: 8 pages 2 figures Latex, submitted to Phys. Rev. Letter

Measurement of the 2H(n,γ)3H reaction cross section between 10 and 550 keV

We have measured for the first time the cross section of the 2H(n,γ)3H reaction at an energy relevant to big-bang nucleosynthesis by employing a prompt discrete -ray detection method. The outgoing photons have been detected by means of anti-Compton NaI(Tl) spectrometers with a large signal-to-noise ratio. The resulting cross sections are 2.23±0.34,1.99±0.25, and 3.76±0.41µb at En=30.5,54.2, and 531 keV, respectively. At En=30.5 keV the cross section differs from the value reported previously by a factor of 2. Based on the present data the reaction rate has been obtained for temperatures in the range 107-1010 K. The astrophysical impact of the present result is discussed. The obtained cross sections are compared with a theoretical calculation based on the Faddeev approach, which includes meson exchange currents as well as a three-nucleon force