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Nuclear Theory·nucl-th

Monday·October 4, 2021

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 01

    Effects of Many-body Interactions in Hypernuclei with Korea-IBS-Daegu-SKKU Functionals

    Soonchul Choi🇰🇷 · Emiko Hiyama🇯🇵 · Chang Ho Hyun🇰🇷 · Myung-Ki Cheoun🇰🇷

    We investigate the properties of hyperon in -hypernuclei using an effective nuclear density functional theory which is based on the low-energy effective field theory. It expands the energy density in the power of Fermi momentum, and consequently has multiple density dependence for the effective many-body interactions. Starting from the effective density functional for nucleons, we determine the parameters for the two- and many-body - interactions added to the nucleon energy density functional by fitting to -hypernuclear data. The experimental data consist of the energy levels of a hyperon in the -, and -states as well as -state of -hypernuclei in the mass range from O to Pb. The results turn out to properly explain the data relevant to hypernuclei owing to the effective many-body interaction apart from a few data in light hypernuclei. This hyperon functional is applied to study the hyperon binding energy of the neutron-rich Sn isotopes which are under consideration for the measurement at J-PARC. Our results are shown to be insensitive to the density dependence of symmetry energy. We also examine the nuclear matter including hyperon. We note that the hyperon threshold density depends on the nuclear matter properties.

    nucl-thnucl-exEPJA(2022)·9 citations
  2. 02

    Constraints on high density equation of state from maximum neutron star mass

    Márcio Ferreira🇵🇹 · Constança Providência🇵🇹

    The low density nuclear matter equation of state is strongly constrained by nuclear properties, however, for constraining the high density equation of state it is necessary to resort to indirect information obtained from the observation of neutron stars, compact objects that may have a central density several times nuclear matter saturation density, . Taking a meta-modelling approach to generate a huge set of equation of state that satisfy nuclear matter properties close to and that do not contain a first order phase transition, the possibility of constraining the high density equation of state was investigated. The entire information obtained from the GW170817 event for the probability distribution of was used to make a probabilistic inference of the EOS, which goes beyond the constraints imposed by nuclear matter properties. Nuclear matter properties close to saturation, below , do not allow us to distinguish between equations of state that predict different neutron star (NS) maximum masses. This is, however, not true if the equation of state is constrained at low densities by the tidal deformability of the NS merger associated to GW170817. Above , differences may be large, for both approaches, and, in particular, the pressure and speed of sound of the sets studied do not overlap, showing that the knowledge of the NS maximum mass may give important information on the high density EOS. Narrowing the maximum mass uncertainty interval will have a sizeable effect on constraining the high density EOS.

    nucl-thastro-ph.HEhep-phPRD(2021)·34 citations
  3. 03

    Properties of the neutron star crust: Quantifying and correlating uncertainties with improved nuclear physics

    G. Grams🇫🇷 · R. Somasundaram🇫🇷 · J. Margueron🇫🇷 · S. Reddy🇺🇸

    A compressible liquid-drop model (CLDM) is used to correlate uncertainties associated with the properties of the neutron star (NS) crust with theoretical estimates of the uncertainties associated with the equation of state (EOS) of homogeneous neutron and nuclear matter. For the latter, we employ recent calculations based on Hamiltonians constructed using Chiral Effective Field theory. Fits to experimental nuclear masses are employed to constrain the CLDM further, and we find that they disfavor some of the Chiral Hamiltonians. The CLDM allows us to study the complex interplay between bulk, surface, curvature, and Coulomb contributions, and their impact on the NS crust. It also reveals how the curvature energy alters the correlation between the surface energy and the bulk symmetry energy. Our analysis quantifies how the uncertainties associated with the EOS of homogeneous matter implies significant uncertainties for the composition of the crust, its proton fraction, and the volume fraction occupied by nuclei. We find that the finite-size effects impact the crust composition, but have a negligible effect on the net isospin asymmetry of matter. The isospin asymmetry is largely determined by the bulk properties and the isospin dependence of the surface energy. The most significant uncertainties associated with matter properties in the densest regions of the crust, the precise location of the crust-core transition, are found to be strongly correlated with uncertainties associated with the Hamiltonians. By adopting a unified model to describe the crust and the core of NSs, we tighten the correlation between their global properties such as their mass-radius relationship, moment of inertia, crust thickness, and tidal deformability with uncertainties associated with the nuclear Hamiltonians.

    nucl-thPRC(2022)·33 citations
  4. 04

    Nuclear symmetry energy components and their ratio: A new approach within the coherent density fluctuation model

    M. K. Gaidarov · E. Moya de Guerra · A. N. Antonov · I. C. Danchev · P. Sarriguren · D. N. Kadrev

    A new alternative approach to calculate the ratio of the surface to volume components of the nuclear symmetry energy is proposed in the framework of the coherent density fluctuation model (CDFM). A new expression (scheme II) for the ratio is derived consistently within the model. This expression appears in a form more direct and physically motivated than the expression (scheme I) that was used in our previous works within the CDFM and avoids preliminary assumptions and mathematical ambiguities in scheme I. The calculations are based on the Skyrme and Brueckner energy-density functionals for nuclear matter and on nonrelativistic Brueckner-Hartree-Fock method with realistic Bonn B and Bonn CD nucleon-nucleon potentials. The approach is applied to isotopic chains of Ni, Sn, and Pb nuclei using nuclear densities obtained in self-consistent Hartree-Fock+BCS calculations with SLy4 Skyrme effective interaction. The applicability of both schemes within the CDFM is demonstrated by a comparison of the results with the available empirical data and with results of other theoretical studies of the considered quantities. Although in some instances the results obtained for the studied ratio and the symmetry energy components are rather close in both schemes, the new scheme II leads to more realistic values that agree better with the empirical data and exhibits conceptual and operational advantages.

    nucl-thPRC(2021)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE