Search

In this work we study the performances of our microscopic optical potential [1, 2], derived from nucleon-nucleon chiral potentials at fifth order (N4LO), in comparison with those of a successful non-relativistic phenomenological optical potential in the description of elastic proton scattering data on tin and lead isotopes at energies around and above 200 MeV. Our results indicate that microscopic optical potentials derived from nucleon-nucleon chiral potentials at N4LO can provide reliable predictions for observables of stable and exotic nuclei, even at energies where the robustness of the chiral expansion starts to be questionable.

The ¹So pairing gap in isospin-symmetric nuclear matter and finite nuclei is investigated using the chiral nucleon-nucleon potential at the next-to-next-to-next-to-leading order (N³LO) order in the two-body sector and the next-to-next-to-leading order (N²LO) order in the three-body sector. To include realistic nuclear forces in the relativistic Hartree-Bogoliubov (RHB) framework, we employ a separable form of the pairing interaction that is adjusted to the nuclear matter pairing gap computed with a bare nuclear force. The separable pairing force is applied to the analysis of pairing properties for several isotopic and isotonic chains of spherical nuclei. [ABSTRACT FROM AUTHOR]

Background: Elastic scattering is a very important process to understand nuclear interactions in finite nuclei. Despite decades of efforts, the goal of reaching a coherent description of this physical process in terms of microscopic forces is still far from being completed. Purpose: In previous papers we derived a nonrelativistic theoretical optical potential from nucleon-nucleon chiral potentials at fourth (N³LO) and fifth order (N4LO). We checked convergence patterns and established theoretical error bands. With this work we study the performances of our optical potential in comparison with those of a successful nonrelativistic phenomenological optical potential in the description of elastic proton scattering data on several isotopic chains at energies around and above 200 MeV. Methods: We use the same framework and the same approximations as adopted in our previous papers, where the nonrelativistic optical potential is derived at the first-order term within the spectator expansion of the multiple scattering theory and adopting the impulse approximation and the optimum factorization approximation. Results: The cross sections and analyzing powers for elastic proton scattering off calcium, nickel, tin, and lead isotopes are presented for several incident proton energies, exploring the range 156≤E≤333 MeV, where experimental data are available. In addition, we provide theoretical predictions for 56Ni at 400 MeV, which is of interest for the future experiments at EXL. Conclusions: Our results indicate that microscopic optical potentials derived from nucleon-nucleon chiral potentials at N4LO can provide reliable predictions for the cross section and the analyzing power both of stable and exotic nuclei, even at energies where the reliability of the chiral expansion starts to be questionable. [ABSTRACT FROM AUTHOR]

Background: Elastic scattering is probably the main event in the interactions of nucleons with nuclei. Even if this process has been extensively studied in the past years, a consistent description, i.e., starting from microscopic two- and many-body forces connected by the same symmetries and principles, is still under development. Purpose: In a previous paper [M. Vorabbi, P. Finelli, and C. Giusti, Phys. Rev. C 93, 034619 (2016)] we derived a theoretical optical potential from NN chiral potentials at fourth order (N³LO). In the present work we use NN chiral potentials at fifth order (N4LO), with the purpose to check the convergence and to assess the theoretical errors associated with the truncation of the chiral expansion in the construction of an optical potential. Methods: Within the same framework and with the same approximations as the previous paper [M. Vorabbi, P. Finelli, and C. Giusti, Phys. Rev. C 93, 034619 (2016)], the optical potential is derived as the first-order term within the spectator expansion of the nonrelativistic multiple scattering theory and adopting the impulse approximation and the optimum factorization approximation. Results: The pp and np Wolfenstein amplitudes and the cross section, analyzing power, and spin rotation of elastic proton scattering from 16O, 12C, and 40Ca nuclei are presented at an incident proton energy of 200 MeV. The results obtained with different versions of chiral potentials at N4LO are compared. Conclusions: Our results indicate that convergence has been reached at N4LO. The agreement with the experimental data is comparable with the agreement obtained in the previous paper [M. Vorabbi, P. Finelli, and C. Giusti, Phys. Rev. C 93, 034619 (2016)]. We confirm that building an optical potential within chiral perturbation theory is a promising approach for describing elastic proton-nucleus scattering. [ABSTRACT FROM AUTHOR]

Background: Elastic scattering is probably the main event in the interactions of nucleons with nuclei. Even if this process has been extensively studied over the last years, a consistent description, i.e., starting from microscopic two- and many-body forces connected by the same symmetries and principles, is still under development. Purpose: In this work we study the domain of applicability of microscopic two-body chiral potentials in the construction of an optical potential. Methods: We basically follow the Kerman, McManus, and Thaler approach [Ann. Phys. (NY) 8, 551 (1959)] to build a microscopic complex optical potential, and then we perform some test calculations on 16O at different energies. Results:. Our conclusion is that a particular set of potentials with a Lippmann-Schwinger cutoff at relatively high energies (above 500 MeV) reproduces best the scattering observables. Conclusions: Our work shows that building an optical potential within chiral perturbation theory is a promising approach for describing elastic proton scattering; in particular, in view of the future inclusion of many-body forces that naturally arises in such a framework. [ABSTRACT FROM AUTHOR]

Background: An accurate description of nuclear pairing gaps is extremely important for understanding static and dynamic properties of the inner crusts of neutron stars and to explain their cooling process. Purpose: We plan to study the behavior of the pairing gaps ΔF as a function of the Fermi momentum kF for neutron and nuclear matter in all relevant angular momentum channels where superfluidity is believed to naturally emerge. The calculations will employ realistic chiral nucleon-nucleon potentials with the inclusion of three-body forces and self-energy effects. Methods: The superfluid states of neutron and nuclear matter are studied by solving the BCS gap equation for chiral nuclear potentials using the method suggested by Khodel et al., where the original gap equation is replaced by a coupled set of equations for the dimensionless gap function Χ(k) defined by Δ(k) = ΔFΧ(k) and a nonlinear algebraic equation for the gap magnitude ΔF = Δ(kF) at the Fermi surface. This method is numerically stable even for small pairing gaps, such as that encountered in the coupled ³PF2 partial wave. Results: We have successfully applied Khodel's method to singlet (S) and coupled channel (SD and PF) cases in neutron and nuclear matter. Our calculations agree with other ab initio approaches, where available, and provide crucial inputs for future applications in superfluid systems [ABSTRACT FROM AUTHOR]

Elastic scattering of antiprotons off 4He, 12C, and 16,18O is described for the first time with a consistent microscopic approach based on the calculation of an optical potential (OP) describing the antiproton-target interaction. The OP is derived using the recent antiproton-nucleon (p̅N) chiral interaction to calculate the p̅N t matrix, while the target densities are computed with the ab initio no-core shell model using chiral interactions as well. Our results are in good agreement with the existing experimental data and the results computed at different chiral orders of the p̅N interaction display a well-defined convergence pattern. [ABSTRACT FROM AUTHOR]

We present and discuss numerical predictions for the neutron density distribution of 208Pb using various nonrelativistic and relativistic mean-field models for the nuclear structure. Our results are compared with the very recent pion photoproduction data from Mainz. The parity-violating asymmetry parameter for elastic electron scattering at the kinematics of the PREX experiment at JLab and the neutron skin thickness are compared with the available data. We consider also the dependence between the neutron skin and the parameters of the expansion of the symmetry energy. [ABSTRACT FROM AUTHOR]

We present theoretical predictions for electron scattering on the N = 14,20, and 28 isotonic chains from proton-deficient to proton-rich nuclei. The calculations are performed within the framework of the distorted-wave Born approximation and the proton and neutron density distributions are evaluated adopting a relativistic Hartree-Bogoliubov (RHB) approach with a density dependent meson-exchange interaction. We present results for the elastic and quasi-elastic cross sections and for the parity-violating asymmetry parameter. Owing to the correlations between the evolution of the electric charge form factors along each chain with the underlying proton shell structure of the isotones, elastic electron scattering experiments on isotones can provide useful information about the occupation and filling of the single-particle levels of protons. [ABSTRACT FROM AUTHOR]

We present theoretical predictions for electron scattering on oxygen and calcium isotopic chains. The calculations are done within the framework of the distorted-wave Born approximation and the proton and neutron density distributions are evaluated adopting a relativistic Dirac-Hartree model. We present results for the elastic and quasi-elastic cross sections and for the parity-violating asymmetry. As a first step, the results of the models are tested in comparison with some of the data available for elastic and quasi-elastic scattering on 16O and 40Ca nuclei. Then, the evolution of some nuclear properties is investigated as a function of the neutron number. We also present a comparison with the parity-violating asymmetry parameter obtained by the PREX Collaboration on 208Pb and give a prediction for the future experiment CREX on 48Ca. [ABSTRACT FROM AUTHOR]