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Nuclear Theory·nucl-th

Tuesday·July 28, 2015

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 24 Jul 2015]

    Short-range correlations in the deuteron: chiral effective field theory, meson-exchange, and phenomenology

    Francesca Sammarruca🇺🇸

    We study high-momentum distributions and short-range correlation probabilities in the deuteron with a variety of modern potentials based on chiral effective field theory up to fifth order in the chiral expansion. We also consider some conventional (meson-exchange and phenomenological) interactions. We examine our predictions in the context of short-range correlation probabilities as extracted from analyses of inclusive electron scattering data and discuss whether modern interac- tions can be reconciled with the latter.

    Comments:
    11 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1507.07043 [pdf]
    PRC(2015)·10 citations
  2. 02

    [Submitted on 26 Jul 2015]

    Halo effective field theory constrains the solar Beryllium-7 + proton -> Boron-8 + photon rate

    Xilin Zhang · Kenneth M. Nollett · D. R. Phillips

    We report an improved low-energy extrapolation of the cross section for the process Beryllium-7+proton -> Boron-8+photon, which determines the Boron-8 neutrino flux from the Sun. Our extrapolant is derived from Halo Effective Field Theory (EFT) at next-to-leading order. We apply Bayesian methods to determine the EFT parameters and the low-energy S-factor, using measured cross sections and scattering lengths as inputs. Asymptotic normalization coefficients of Boron-8 are tightly constrained by existing radiative capture data, and contributions to the cross section beyond external direct capture are detected in the data at E < 0.5 MeV. Most importantly, the S-factor at zero energy is constrained to be S(0)= 21.3 + - 0.7 eV b, which is an uncertainty smaller by a factor of two than previously recommended. That recommendation was based on the full range for S(0) obtained among a discrete set of models judged to be reasonable. In contrast, Halo EFT subsumes all models into a controlled low-energy approximant, where they are characterized by nine parameters at next-to-leading order. These are fit to data, and marginalized over via Monte Carlo integration to produce the improved prediction for S(E).

    Comments:
    7 pages, 3 figures, 2 tables, and 1 supplemental material
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
    arXiv:
    1507.07239 [pdf]
    PLB(2015)·64 citations
  3. 03

    [Submitted on 27 Jul 2015]

    Nuclear matter equation of state from a quark-model nucleon-nucleon interaction

    K. Fukukawa🇮🇹 · M. Baldo🇮🇹 · G. F. Burgio🇮🇹 · L. Lo Monaco🇮🇹 · H.-J. Schulze🇮🇹

    Starting from a realistic constituent quark model for the nucleon-nucleon interaction, we derive the equation of state (EOS) of nuclear matter within the Bethe-Brueckner-Goldstone approach up to three-hole-line level, without need to introduce three-nucleon forces. To estimate the uncertainty of the calculations both the gap and the continuous choices for the single-particle potential are considered and compared. The resultant EOS is compatible with the phenomenological analysis on the saturation point, the incompressibility, the symmetry energy at low density and its slope at saturation, together with the high-density pressure extracted from flow data on heavy ion collisions. Although the symmetry energy is appreciably larger in the gap choice in the high-density region, the maximum neutron star masses derived from the continuous-choice EOS and the gap-choice EOS are similar and close to two solar masses, which is again compatible with recent observational data. Comparison with other microscopic EOS is presented and discussed.

    Comments:
    15 pages, 11 figures, 8 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1507.07288 [pdf]
    PRC(2015)·29 citations
  4. 04

    [Submitted on 27 Jul 2015]

    Large scale evaluation of beta-decay rates of r-process nuclei with the inclusion of first-forbidden transitions

    T. Marketin · L. Huther · G. Martínez-Pinedo

    R-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are beta-decay half-lives of neutron rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. We use a fully self-consistent covariant density functional theory (CDFT) framework to provide a table of -decay half-lives and -delayed neutron emission probabilities, including first-forbidden transitions. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced, both for even-even, odd-A and odd-odd nuclei, in particular for short-lived nuclei.

    Comments:
    18 pages, 17 figures, submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    1507.07442 [pdf]
    PRC(2016)·280 citations

Affiliations

first authorsco-authorsvia INSPIRE