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Nuclear Theory·nucl-th

Wednesday·July 1, 2015

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 30 Jun 2015]

    Spectra and Scattering of Light Lattice Nuclei from Effective Field Theory

    Johannes Kirscher🇮🇱 · Nir Barnea🇮🇱 · Doron Gazit🇮🇱 · Francesco Pederiva🇮🇹 · Ubirajara van Kolck🇫🇷

    An effective field theory is used to describe light nuclei, calculated from quantum chromodynamics on a lattice at unphysically large pion masses. The theory is calibrated at leading order to two available data sets on two- and three-body nuclei for two pion masses. At those pion masses we predict the quartet and doublet neutron-deuteron scattering lengths, and the alpha-particle binding energy. For MeV we obtain, respectively, fm, fm, and MeV, while for MeV fm, fm, and MeV are found. Phillips- and Tjon-like correlations to the triton binding energy are established. Higher-order effects on the respective correlation bands are found insensitive to the pion mass. As a benchmark, we present results for the physical pion mass, using experimental two-body scattering lengths and the triton binding energy as input. Hints of subtle changes in the structure of the triton and alpha particle are discussed.

    Comments:
    19 pages, 8 figures, 4 tables, submitted to PRC
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
    arXiv:
    1506.09048 [pdf]
    PRC(2015)·55 citations
  2. 02

    [Submitted on 30 Jun 2015]

    Symmetry energy systematics and its high density behavior

    Lie-Wen Chen🇨🇳

    We explore the systematics of the density dependence of nuclear matter symmetry energy in the ambit of microscopic calculations with various energy density functionals, and find that the symmetry energy from subsaturation density to supra-saturation density can be well determined by three characteristic parameters of the symmetry energy at saturation density , i.e., the magnitude , the density slope and the density curvature . This finding opens a new window to constrain the supra-saturation density behavior of the symmetry energy from its (sub-)saturation density behavior. In particular, we obtain MeV and MeV as well as MeV and MeV based on the present knowledge of MeV, MeV and MeV at fm extracted from nuclear mass and the neutron skin thickness of Sn isotopes. Our results indicate that the symmetry energy cannot be stiffer than a linear density dependence.In addition, we also discuss the quark matter symmetry energy since the deconfined quarks could be the right degree of freedom in dense matter at high baryon densities.

    Comments:
    10 pages, 5 figures. Contribution to International Workshop on Multi facets of Eos and Clustering (IWM-EC 2014), May 6-9, 2014, Catania, Italy
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
    arXiv:
    1506.09057 [pdf]
    EPJ Web Conf.(2015)·32 citations
  3. 03

    [Submitted on 30 Jun 2015]

    Electromagnetic multipoles - theory issues

    M.M. Giannini🇮🇹

    Some predictions of the Hypercentral Constituent Quark Model for the helicity amplitudes are discussed and compared with data and with the recent analysis of the Mainz group; the role of the pion cloud contribution in explaining the major part of the missing strength at low is emphasized.

    Comments:
    Physics of excited nucleons (J.-P. Bocquet, V. Kuznetsov, D. Rebreyend eds.), World Scientific, Singapore 2004, 377-381 BRAG Meeting, Grenoble 23 March 2004
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1506.09188 [pdf]
    0 citations
  4. 04

    [Submitted on 30 Jun 2015]

    Nuclear Energy Density Functionals: What do we really know?

    Aurel Bulgac · Michael McNeil Forbes · Shi Jin

    We present the simplest nuclear energy density functional (NEDF) to date, determined by only 4 significant phenomenological parameters, yet capable of fitting measured nuclear masses with better accuracy than the Bethe-Weizsäcker mass formula, while also describing density structures (charge radii, neutron skins etc.) and time-dependent phenomena (induced fission, giant resonances, low energy nuclear collisions, etc.). The 4 significant parameters are necessary to describe bulk nuclear properties (binding energies and charge radii); an additional 2 to 3 parameters have little influence on the bulk nuclear properties, but allow independent control of the density dependence of the symmetry energy and isovector excitations, in particular the Thomas-Reiche-Kuhn sum rule. This Hohenberg-Kohn-style of density functional theory successfully realizes Weizsäcker's ideas and provides a computationally tractable model for a variety of static nuclear properties and dynamics, from finite nuclei to neutron stars, where it will also provide a new insight into the physics of the r-process, nucleosynthesis, and neutron star crust structure. This new NEDF clearly separates the bulk geometric properties - volume, surface, symmetry, and Coulomb energies which amount to 8MeV per nucleon or up to 2000MeV per nucleus for heavy nuclei - from finer details related to shell effects, pairing, isospin breaking, etc. which contribute at most a few MeV for the entire nucleus. Thus it provides a systematic framework for organizing various contributions to the NEDF. Measured and calculated physical observables - symmetry and saturation properties, the neutron matter equation of state, and the frequency of giant dipole resonances - lead directly to new terms not considered in current NEDF parameterizations.

    Comments:
    25 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    1506.09195 [pdf]
    14 citations

Affiliations

first authorsco-authorsvia INSPIRE