PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·February 25, 2015

4 papers—3 primary·1 cross-listed

All4Primary3Cross-lists1
  1. 01

    [Submitted on 24 Feb 2015]

    Nuclear Lattice Simulations using Symmetry-Sign Extrapolation

    Timo A. Lähde🇩🇪 · Thomas Luu🇩🇪 · Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪 · Evgeny Epelbaum🇩🇪 · Hermann Krebs🇩🇪 · Gautam Rupak🇺🇸

    Projection Monte Carlo calculations of lattice Chiral Effective Field Theory suffer from sign oscillations to a varying degree dependent on the number of protons and neutrons. Hence, such studies have hitherto been concentrated on nuclei with equal numbers of protons and neutrons, and especially on the alpha nuclei where the sign oscillations are smallest. Here, we introduce the "symmetry-sign extrapolation" method, which allows us to use the approximate Wigner SU(4) symmetry of the nuclear interaction to systematically extend the Projection Monte Carlo calculations to nuclear systems where the sign problem is severe. We benchmark this method by calculating the ground-state energies of the C, He and Be nuclei, and discuss its potential for studies of neutron-rich halo nuclei and asymmetric nuclear matter.

    Comments:
    25 pages, 12 figures, version to appear in Eur. Phys. J. A
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1502.06787 [pdf]
    EPJA(2015)·44 citations
  2. 02

    [Submitted on 24 Feb 2015]

    Emergence of a secondary rainbow and the dynamical polarization potential for 16O on 12C at 330 MeV

    R.S. Mackintosh · Y. Hirabayashi · S. Ohkubo

    Background: An anomaly in the elastic scattering of O-16 on C-12 around 300 MeV was resolved by including collective excitations of both nuclei, leading to a secondary rainbow. There is little systematic knowledge of the contribution of collective excitations to the interaction between nuclei, particularly in the overlap region of heavy nuclei. Purpose: To study the dynamic polarization potential (DPP) generated by channel coupling that had been validated for a case where scattering is sensitive to the nuclear potential over a wide radial range; to exhibit evidence of the non-locality due to collective coupling; to validate, or otherwise, the representation of DPPs by uniform renormalization of potentials. Methods: S-matrix to potential inversion yields local potentials reproducing the elastic channel S-matrix of coupled channel calculations. Subtracting the elastic channel uncoupled potential yields a local L-independent representation of the DPP. The dependence of the DPP on the nature of the coupled states and other parameters can be studied. Results: Local DPPs were found due to the excitation of C-12 and the combined excitation of O-16 and C-12. The radial forms found were very different from uniform renormalization of the potential. Full coupling led to a 10 percent increase in the volume integral of the real potential. Evidence for the non-locality of the underlying formal DPP and the effect of direct coupling between the collective states is found. Conclusions: The local DPP generating the secondary rainbow is found. DPPs have forms depending on the specific excitations and cannot be represented by a uniform renormalization of the potential. The method is useful for study of the contribution of collective excitations to internuclear potentials, concerning which remarkably little is known in general.

    Comments:
    9 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.06852 [pdf]
    PRC(2015)·14 citations
  3. 03

    [Submitted on 24 Feb 2015]

    Global study of beyond-mean-field correlation energies in covariant energy density functional theory using a collective Hamiltonian method

    K. Q. Lu · Z. X. Li · Z. P. Li · J. M. Yao · J. Meng

    We report the first global study of dynamic correlation energies (DCEs) associated with rotational motion and quadrupole shape vibrational motion in a covariant energy density functional (CEDF) for 575 even-even nuclei with proton numbers ranging from to by solving a five-dimensional collective Hamiltonian, the collective parameters of which are determined from triaxial relativistic mean-field plus BCS calculation using the PC-PK1 force. After taking into account these beyond mean-field DCEs, the root-mean-square (rms) deviation with respect to nuclear masses is reduced significantly down to 1.14 MeV, which is smaller than those of other successful CEDFs: NL3* (2.96 MeV), DD-ME2 (2.39 MeV), DD-ME (2.29 MeV) and DD-PC1 (2.01 MeV). Moreover, the rms deviation for two-nucleon separation energies is reduced by in comparison with cranking prescription.

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.06908 [pdf]
    PRC(2015)·75 citations

Affiliations

first authorsco-authorsvia INSPIRE