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We derive local microscopic optical potentials U systematically for polarized proton scattering at 65 MeV using the local-potential version of the Melbourne g-matrix folding model. As target nuclei, we take 6 He and neutron-rich Ne isotopes in addition to stable nuclei of mass number A = 4-208 in order to clarify mass-number and isotope dependence of U . The local potentials reproduce the experimental data systematically and have geometries similar to the phenomenological optical potentials for stable targets. The target density is broadened by the weak-binding nature and/or deformation of unstable nuclei. For the real spin-orbit part of U the density broadening weakens the strength and enlarges the radius, whereas for the central part it enlarges both of the strength and the radius. The density-broadening effect is conspicuous for halo nuclei such as 6 He and 31 Ne. Similar discussions are made briefly for proton scattering at 200 MeV. We briefly investigate how the isovector and the non spherical components of U affect proton scattering.

We present a reliable double-folding (DF) model for 4 He-nucleus scattering, using the Melbourne g-matrix nucleon-nucleon interaction that explains nucleon-nucleus scattering with no adjustable parameter. In the DF model, only the target density is taken as the local density in the Melbourne g-matrix. For 4 He elastic scattering from 58 Ni and 208 Pb targets in a wide range of incident energies from 20 MeV/nucleon to 200 MeV/nucleon, the DF model with the target-density approximation (TDA) yields much better agreement with the experimental data than the usual DF model with the frozen-density approximation in which the sum of projectile and target densities is taken as the local density. We also discuss the relation between the DF model with the TDA and the conventional folding model in which the nucleon-nucleus potential is folded with the 4 He density.

We propose a practical folding model to describe 3 He elastic scattering. In the model, 3 He optical potentials are constructed by making the folding procedure twice. First the nucleon-target potential is evaluated by folding the Melbourne g-matrix with the target density and localizing the nonlocal folding potential with the Brieva-Rook method, and second the resulting local nucleon-target potential is folded with the 3 He density. This double single-folding model well describes 3 He elastic scattering from 58 Ni and 208 Pb targets in a wide incident-energy range from 30 MeV/nucleon to 150 MeV/nucleon with no adjustable parameter. Spin-orbit force effects on differential cross sections are found to be appreciable only at higher incident energies such as 150 MeV/nucleon. Three-nucleon breakup effects of 3 He are investigated with the continuum discretized coupled-channels method and are found to be appreciable only at lower incident energies around 40 MeV/nucleon. Effects of knock-on exchange processes are also analyzed.

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We investigate the effects of chiral three-nucleon force (3NF) at NNLO level on nucleon-nucleus (NA) elastic scattering, using the standard framework based on the Brueckner-Hartree-Fock method for nuclear matter and the g-matrix folding model for NA elastic scattering. The optical potential in nuclear matter calculated from chiral two-nucleon force (2NF) at N 3 LO level is found to be close to that from Bonn-B 2NF, whereas the Melbourne g-matrix is known as a practical effective nucleon-nucleon interaction constructed by localizing the g-matrices calculated from Bonn-B 2NF. As the first attempt to estimate chiral-3NF effects on NA scattering, the effects are simply introduced by multiplying the local Melbourne g-matrix by the ratio of the optical potential in nuclear matter calculated from chiral 2NF+3NF to that from chiral 2NF. For NA elastic scattering on various targets at 65 MeV, chiral 3NF makes the folding potential less attractive and more absorptive. The novel property for the imaginary part is originated in the enhancement of tensor correlations due to chiral 3NF (mainly the 2π-exchange diagram). The two effects are small for differential cross sections and vector analyzing powers at the forward and middle angles where the experimental data are available. If backward measurements are made, the data will reveal the effects of chiral 3NF.

Background: It is a current important subject to clarify properties of chiral three-nucleon forces (3NFs) not only in nuclear matter but also in scattering between finite-size nuclei. Particularly for the elastic scattering, this study has just started and the properties are not understood in a wide range of incident energies (Ein). Aims and approach: We investigate basic properties of chiral 3NFs in nuclear matter with positive energies by using the Brueckner-Hartree-Fock method with chiral two-nucleon forces at N 3 LO and 3NFs at NNLO, and analyze effects of chiral 3NFs on 4 He elastic scattering from targets 208 Pb, 58 Ni and 40 Ca over a wide range of 30 < ∼ Ein/AP < ∼ 200 MeV by using the g-matrix folding model, where AP is the mass number of the projectile. Results: In symmetric nuclear matter with positive energies, chiral 3NFs make the single-particle potential less attractive and more absorptive. The effects mainly come from the Fujita-Miyazawa 2π-exchange 3NF and slightly become larger as Ein increases. These effects persist in the optical potentials of 4 He scattering. As for the differential cross sections of 4 He scattering, chiral-3NF effects are large in Ein/AP > ∼ 60 MeV and improve the agreement of the theoretical results with the measured ones. Particularly in Ein/AP > ∼ 100 MeV, the folding model reproduces measured differential cross sections pretty well. Cutoff (Λ) dependence is investigated for both nuclear matter and 4 He scattering by considering two cases of Λ = 450 and 550 MeV. The uncertainty coming from the dependence is smaller than chiral-3NF effects even at Ein/AP = 175 MeV. PACS numbers: 21.30.Fe, 24.10.Ht, 25.55.Ci FIG. 1: 3NFs in NNLO. Diagram (a) corresponds to the Fujita-Miyazawa 2π-exchange 3NF [1], and diagrams (b) and (c) correspond to 1π-exchange and contact 3NFs. The solid and dashed lines denote nucleon and pion propagations, respectively, and filled circles and squares stand for vertices. The strength of the filled-square vertex is often called cD in diagram (b) and cE in diagram (c).tact 3NFs, respectively. The filled-square vertex has a strength c D in the diagram (b) and c E in the diagram (c). Quantitative roles of chiral 3NFs were extensively investigated, particularly for light nuclei and nuclear matter [6]; more precisely, see Ref.[7] for light nuclei, Refs. [8,9] for ab initio nuclear-structure calculations in lighter nuclei and Refs. [10][11][12][13][14][15][16] for nuclear matter. In addition, effects of chiral four-nucleon forces were found to be small in nuclear matter [17,18]. The chiral g matrix, calculated from chiral 2NF+3NF with the Brueckner-Hartree-Fock (BHF) method, yields a reasonable nuclear matter sat-