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Register a new userLongitudinal response function of 4He with a realistic force
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The longitudinal response function of 4He is calculated with the Argonne V18 potential. The comparison with experiment suggests the need of a three-body force. When adding the Urbana IX three-body potential in the calculation of the lower longitudinal multipoles, the total strength is suppressed in the quasi-elastic peak, towards the trend of the experimental data.
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The 4He total photoabsorption cross section is calculated with the realistic nucleon-nucleon potential Argonne V18 and the three-nucleon force (3NF) Urbana IX. Final state interaction is included rigorously via the Lorentz Integral Transform method. A rather pronounced giant resonance with peak cross sections of 3 (3.2) mb is obtained with (without) 3NF. Above 50 MeV strong 3NF effects, up to 35%, are present. Good agreement with experiment is found close to threshold. A comparison in the giant resonance region is inconclusive, since present data do not show a unique picture.
We present a consistent emph{ab initio} computation of the longitudinal response function $R_L$ in $^{40}$Ca using the coupled-cluster and Lorentz integral transform methods starting from chiral nucleon-nucleon and three-nucleon interactions. We validate our approach by comparing our results for $R_L$ in $^4$He and the Coulomb sum rule in $^{40}$Ca against experimental data and other calculations. For $R_L$ in $^{40}$Ca we obtain a very good agreement with experiment in the quasi-elastic peak up to intermediate momentum transfers, and we find that final state interactions are essential for an accurate description of the data. This work presents a milestone towards emph{ab initio} computations of neutrino-nucleus cross sections relevant for experimental long-baseline neutrino programs.
Linear density response functions are calculated for symmetric nuclear matter of normal density by time-evolving two-time Greens functions in real time. The feasability and convenience of this approach to this particular problem has been shown in previous publications. Calculations are here improved by using more realistic interactions derived from phase-shifts by inverse scattering. Of particular interest is the effect of the strong correlations in the nuclear medium on the response. This as well as the related energy weighted sum rule, dependence on mean field and effective mass are some of the main objects of this investigation. Comparisons are made with the collision-less limit, the HF+RPA method. The importance of vertex corrections is demonstrated.
We report on a consistent, microscopic calculation of the bound and scattering states in the 4He system employing modern realistic two-nucleon and three-nucleon potentials in the framework of the resonating group model (RGM). We present for comparison with these microscopic RGM calculations the results from a charge-independent, Coulomb-corrected R-matrix analysis of all types of data for reactions in the A=4 system. Comparisons are made for selected examples of phase shifts and measurements from reactions sensitive to three-nucleon force effects.
We report on microscopic calculations for the 4He compound system in the framework of the resonating group model employing realistic nucleon-nucleon and three nucleon forces. The resulting scattering phase shifts are compared to those of a comprehensive R-matrix analysis of all data in this system, which are available in numerical form. The agreement between calculation and analysis is in most cases very good. Adding three-nucleon forces yields in many cases large effects. For a few cases the new agreement is striking. We relate some differencies between calculation and analysis to specific data and discuss neccessary experiments to clarify the situation. From the results we conclude that the data of the 4He system might be well suited to determine the structure of the three-nucleon force.
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