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Nuclear Theory·nucl-th

Thursday·March 5, 2020

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    On collective octupole degrees of freedom -- next pieces of the formal background

    L. Prochniak

    The concept of an intrinsic system can be extended to the case of collective octupole degrees of freedom by exploiting the symmetry properties with respect to transformations of the octahedral group O_h. Explicit formulas for scalar invariants as polynomials of intrinsic variables are presented. A method of constructing a basis in the space of functions on the octupole intrinsic space is proposed.

    nucl-thActa Phys.Polon.Supp.(2020)·0 citations
  2. 02

    Parametrisations of relativistic energy density functionals with tensor couplings

    Stefan Typel · Diana Alvear Terrero

    The relativistic density functional with minimal density dependent nucleon-meson couplings for nuclei and nuclear matter is extended to include tensor couplings of the nucleons to the vector mesons. The dependence of the minimal couplings on either vector or scalar densities is explored. New parametrisations are obtained by a fit to nuclear observables with uncertainties that are determined self-consistently. The corresponding nuclear matter parameters at saturation are determined including their uncertainties. An improvement in the description of nuclear observables, in particular for binding energies and diffraction radii, is found when tensor couplings are considered, accompanied by an increase of the Dirac effective mass. The equations of state for symmetric nuclear matter and pure neutron matter are studied for all models. The density dependence of the nuclear symmetry energy, the Dirac effective masses and scalar densities is explored. Problems at high densities for parametrisations using a scalar density dependence of the couplings are identified due to the rearrangement contributions in the scalar self-energies that lead to vanishing Dirac effective masses.

    nucl-thnucl-exEPJA(2020)·35 citations
  3. 03

    Magnetic dipole excitations based on the relativistic nuclear energy density functional

    G. Kruzic · T. Oishi · D. Vale · N. Paar

    Magnetic dipole (M1) excitations build not only a fundamental mode of nucleonic transitions, but they are also relevant for nuclear astrophysics applications. We have established a theory framework for description of M1 transitions based on the relativistic nuclear energy density functional. For this purpose the relativistic quasiparticle random phase approximation (RQRPA) is established using density dependent point coupling interaction DD-PC1, supplemented with the isovector-pseudovector interaction channel in order to study unnatural parity transitions. The introduced framework has been validated using the M1 sum rule for core-plus-two-nucleon systems, and employed in studies of the spin, orbital, isoscalar and isovector M1 transition strengths, that relate to the electromagnetic probe, in magic nuclei Ca and Pb, and open shell nuclei Ca and Ti. In these systems, the isovector spin-flip M1 transition is dominant, mainly between one or two spin-orbit partner states. It is shown that pairing correlations have a significant impact on the centroid energy and major peak position of the M1 mode. The M1 excitations could provide an additional constraint to improve nuclear energy density functionals in the future studies.

    nucl-thnucl-exPRC(2020)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE