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Nuclear Theory·nucl-th

Thursday·March 19, 2020

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 01

    [Submitted on 17 Mar 2020]

    Rotational excitations in rare-earth nuclei: a comparative study within three cranking models with different mean fields and the treatments of pairing correlations

    Zhen-Hua Zhang🇨🇳 · Miao Huang🇨🇳 · A.V.Afanasjev🇺🇸

    High-spin rotational bands in rare-earth Er (), Tm () and Yb () isotopes are investigated by three different nuclear models. These are (i) the cranked relativistic Hartree-Bogoliubov (CRHB) approach with approximate particle number projection by means of the Lipkin-Nogami (LN) method, (ii) the cranking covariant density functional theory (CDFT) with pairing correlations treated by a shell-model-like approach (SLAP) or the so called particle-number conserving (PNC) method, and (iii) cranked shell model (CSM) based on the Nilsson potential with pairing correlations treated by the PNC method. A detailed comparison between these three models in the description of the ground state rotational bands of even-even Er and Yb isotopes is performed. The similarities and differences between these models in the description of the moments of inertia, the features of band crossings, equilibrium deformations and pairing energies of even-even nuclei under study are discussed. These quantities are considered as a function of rotational frequency and proton and neutron numbers. The changes in the properties of the first band crossings with increasing neutron number in this mass region are investigated. On average, a comparable accuracy of the description of available experimental data is achieved in these models. However, the differences between model predictions become larger above the first band crossings. Because of time-consuming nature of numerical calculations in the CDFT-based models, a systematic study of the rotational properties of both ground state and excited state bands in odd-mass Tm nuclei is carried out only by the PNC-SCM. With few exceptions, the rotational properties of experimental 1-quasiparticle and 3-quasiparticle bands in Tm are reproduced reasonably well.

    Comments:
    29 pages, 18 figures. submitted to Physical Review C, revised version with takes into account the suggestions of referee
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2003.07902 [pdf]
    PRC(2020)·28 citations
  2. 02

    [Submitted on 18 Mar 2020]

    The one-pion-exchange potential with contact terms from lattice QCD simulations

    Jinniu Hu🇨🇳 · Ying Zhang · Hong Shen🇨🇳 · Hiroshi Toki🇯🇵

    The pion-mass-dependent nucleon-nucleon () potentials in term of one-pion exchange and contact terms are obtained from the latest lattice QCD simulations of two-nucleon system, which employ the forms of leading order (LO) potential from the chiral effective field theory and thus are named as the LO chiral potential in this work. We extract the coefficients of contact terms and cut-off momenta in these potentials, for the first time, by fitting the phase shifts of and channels generated by the results of HALQCD collaboration with various pion masses from MeV to MeV. The low-energy constants in the and channels become weaker and approach each other for larger pion masses. These LO chiral potentials are applied to symmetric nuclear and pure neutron matter within the Brueckner-Hartree-Fock method. At this moment, however, we do not have yet the information of the -wave interaction to be provided by the lattice QCD simulations for full description of nuclear matter. Our results will enhance the development of nuclear structure and nuclear matter by controlling the contribution of the pionic effect and illuminate the role of chiral symmetry of the strong interaction in complex system.

    Comments:
    15 pages, 5 figures, 1 table, accepted to Chin. Phys. C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2003.08008 [pdf]
    CPC(2020)·3 citations
  3. 03

    [Submitted on 18 Mar 2020]

    Two-neutron halo structure of F and a novel pairing anti-halo effect

    H. Masui · W. Horiuchi · M. Kimura

    Background: A newly identified dripline nucleus F offers a unique opportunity to study the two-neutron () correlation at the east shore of the island of inversion where the shell closure is lost. Purpose: We aim to present the first three-body theoretical results for the radius and total reaction cross sections of F. This will further help to investigate how the pairing and breakdown of the shell closure influence the formation of the -halo structure and the anti-halo effect in this mass region. Methods: A F three-body system is described by the cluster orbital shell model, and its total reaction cross section is calculated by the Glauber theory. Results: Our three-body calculations predict 3.48-3.70 fm for the root-mean-square radius of F, which corresponds to the total reaction cross section of 1530 (1410)-1640 (1500) mb for a carbon target at 240 (900) MeV/nucleon. The binding mechanism and halo formation in F are discussed. Conclusions: The present study suggests a novel anti-halo effect in this mass region: When the pairing overcome the energy gap between the and orbits, the inversion of the occupation number of these orbits takes place, and it diminishes the -halo structure.

    Comments:
    6 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2003.08044 [pdf]
    PRC(2020)·23 citations
  4. 04

    [Submitted on 18 Mar 2020]

    Coulomb screening correction to the value of the triple alpha process in thermal plasmas

    Lai Hnin Phyu · H. Moriya · W. Horiuchi · K. Iida · K. Noda · M. T. Yamashita

    The triple alpha reaction is a key to C production and is expected to occur in weakly-coupled, thermal plasmas as encountered in normal stars. We investigate how Coulomb screening affects the structure of a system of three alpha particles in such a plasma environment by precise three-body calculations within the Debye-Hückel approximation. A three-alpha model that has the Coulomb interaction modified in the Yukawa form is employed. Precise three-body wave functions are obtained by a superposition of correlated Gaussian bases with the aid of the stochastic variational method. The energy shifts of the Hoyle state due to the Coulomb screening are obtained as a function of the Debye screening length. The results, which automatically incorporate the finite size effect of the Hoyle state, are consistent with the conventional result based on the Coulomb correction to the chemical potentials of ions that are regarded as point charges in a weakly-coupled, thermal plasma. We have given a theoretical basis to the conventional point-charge approach to the Coulomb screening problem relevant for nuclear reactions in normal stars by providing the first evaluation of the Coulomb corrections to the value of the triple alpha process that produces a finite size Hoyle state.

    Comments:
    13 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2003.08060 [pdf]
    PTEP(2020)·5 citations
  5. 05

    [Submitted on 18 Mar 2020]

    Cooling of hybrid neutron stars with microscopic equations of state

    J.-B. Wei🇮🇹 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹 · D. Zappalà🇮🇹

    We model the cooling of hybrid neutron stars combining a microscopic nuclear equation of state in the Brueckner-Hartree-Fock approach with different quark models. We then analyze the neutron star cooling curves predicted by the different models and single out the preferred ones. We find that the possibility of neutron p-wave pairing can be excluded in our scenario.

    Comments:
    10 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2003.08079 [pdf]
    MNRAS(2020)·16 citations
  6. 06

    [Submitted on 18 Mar 2020]

    Enhancement of octupole strength in near spherical nuclei

    L.M. Robledo

    The validity of the rotational formula used to compute E1 and E3 transition strengths in even-even nuclei is analyzed within the Generator Coordinate Method framework based on mean field wave functions. It turns out that those nuclei with spherical or near spherical shapes the E1 and E3 strengths computed with this formula are strongly underestimated and a sound evaluation of them requires angular momentum projected wave functions. Results for several isotopic chains with proton number equal or near magic numbers are analyzed and compared with experimental data. The use of angular momentum projected wave functions greatly improves the agreement with the scarce experimental data.

    Comments:
    7 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2003.08122 [pdf]
    EPJA(2016)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE