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Nuclear Theory·nucl-th

Tuesday·May 25, 2021

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    [Submitted on 22 May 2021]

    Nuclear masses in extended kernel ridge regression with odd-even effects

    X. H. Wu · L. H. Guo · P. W. Zhao

    The kernel ridge regression (KRR) approach is extended to include the odd-even effects in nuclear mass predictions by remodulating the kernel function without introducing new weight parameters and inputs in the training network. By taking the WS4 mass model as an example, the mass for each nucleus in the nuclear chart is predicted with the extended KRR network, which is trained with the mass model residuals, i.e., deviations between experimental and calculated masses, of other nuclei with known masses. The resultant root-mean-square mass deviation from the available experimental data for the 2353 nuclei with and can be reduced to 128 keV, which provides the most precise mass model from machine learning approaches so far. Moreover, the extended KRR approach can avoid the risk of worsening the mass predictions for nuclei at large extrapolation distances, and meanwhile, it provides a smooth extrapolation behavior with respect to the odd and even extrapolation distances.

    Comments:
    6 pages,3 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2105.10634 [pdf]
    PLB(2021)·57 citations
  2. 02

    [Submitted on 23 May 2021]

    Impact of NICER's Radius Measurement of PSR J0740+6620 on Nuclear Symmetry Energy at Suprasaturation Densities

    Nai-Bo Zhang · Bao-An Li

    By directly inverting several neutron star observables in the three-dimensional parameter space for the Equation of State of super-dense neutron-rich nuclear matter, we show that the lower radius limit for PSR J0740+6620 of mass from Neutron Star Interior Composition Explorer (NICER)'s very recent observation sets a much tighter lower boundary than previously known for nuclear symmetry energy in the density range of times the saturation density of nuclear matter. The super-soft symmetry energy leading to the formation of proton polarons in this density region of neutron stars is clearly disfavoured by the first radius measurement for the most massive neutron star observed reliably so far.

    Comments:
    New calculations/discussions/references added. The Astrophysical Journal in press
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    2105.11031 [pdf]
    ApJ(2021)·53 citations
  3. 03

    [Submitted on 24 May 2021]

    Astrophysical S factor and rate of direct capture reaction in a potential model

    E.M. Tursunov · S.A. Turakulov · A.S. Kadyrov · L.D. Blokhintsev

    The astrophysical direct capture process is studied in the framework of a two-body single-channel model with potentials of the Gaussian form. A modified potential is constructed to reproduce the new experimental value of the -wave scattering length and the known astrophysical factor at the Gamow energy, extracted from the solar neutrino flux. The resulting potential is consistent with the theory developed by Baye [Phys. Rev. C {\bf 62} (2000) 065803] according to which the -wave scattering length and the astrophysical factor at zero energy divided by the square of ANC are related. The obtained results for the astrophysical factor at intermediate energies are in good agreement with the two data sets of Hammache {\it et al.} [Phys. Rev. Lett. {\bf 86}, 3985 (2001); {\it ibid.} {\bf 80}, 928 (1998)]. Linear extrapolation to zero energy yields , consistent with the Solar Fusion II estimate. The calculated reaction rates are substantially lower than the results of the NACRE II collaboration.

    Comments:
    16 pages, 5 figures, 2 tables
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2105.11091 [pdf]
    PRC(2021)·9 citations
  4. 04

    [Submitted on 24 May 2021]

    Systematic shell-model study of Rn isotopes with 207 to 216 and isomeric states

    Bharti Bhoy · Praveen C. Srivastava

    We present systematic large-scale shell-model calculations for Rn isotopes with 207 to 216. For the Rn isotopes, we perform calculations with KHH7B interaction, while for Rn isotopes with KHPE and KHH7B interactions. The calculated energies and electromagnetic properties are compared with the available experimental data and predicted where experimental data are not available. We also suggest spins and parities of several unconfirmed states available from the recent experimental data. Comprehensive study of several isomeric states from the calculated shell-model configurations and half-lives is also reported.

    Comments:
    Accepted in Journal of Physics G: Nuclear and Particle Physics (2021)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2105.11096 [pdf]
    J.Phys.G(2021)·11 citations
  5. 05

    [Submitted on 24 May 2021]

    A Realistic Approach to the Bound-State Problem based on Faddeev Equation

    K. Miyagawa🇯🇵 · M. Kohno🇯🇵

    The Faddeev equations for the bound-state problem are solved where the three = baryon-baryon interactions of Jülich-Bonn-München chiral EFT, HAL QCD and Nijmegen ESC08c are used. The -matrix obtained within the original -- -- coupled-channel framework is employed as an input to the equations. We found no bound state for Jülich-Bonn-München chiral EFT and HAL QCD but ESC08c generates a bound state with the total isospin and spin-parity where the decays into are suppressed.

    Comments:
    to appear in the proceedings of APFB2020
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2105.11258 [pdf]
    Few Body Syst.(2021)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE