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Title: Application of density dependent parametrization models to asymmetric nuclear matter

Abstract

Density dependent parametrization models of the nucleon-meson effective couplings, including the isovector scalar {delta}-field, are applied to asymmetric nuclear matter. The nuclear equation of state and the neutron star properties are studied in an effective Lagrangian density approach, using the relativistic mean field hadron theory. It is known that the introduction of a {delta}-meson in the constant coupling scheme leads to an increase of the symmetry energy at high density and so to larger neutron star masses, in a pure nucleon-lepton scheme. We use here a more microscopic density dependent model of the nucleon-meson couplings to study the properties of neutron star matter and to reexamine the {delta}-field effects in asymmetric nuclear matter. Our calculations show that, due to the increase of the effective {delta} coupling at high density, with density dependent couplings the neutron star masses in fact can be even reduced.

Authors:
 [1];  [2]; ;  [3];  [4];  [1];  [2];  [5];  [6]
  1. Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhon 730000 (China)
  2. (China)
  3. Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy)
  4. (Italy)
  5. Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080 (China)
  6. Institute of Theoretical Physics, College of Applied Sciences, Beijing University of Technology, Beijing 100022 (China)
Publication Date:
OSTI Identifier:
20995251
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.75.048801; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ASYMMETRY; COUPLINGS; DENSITY; EQUATIONS OF STATE; ISOVECTORS; LAGRANGIAN FUNCTION; LEPTONS; MASS; MESONS; NEUTRON STARS; NUCLEAR MATTER; NUCLEONS; RELATIVISTIC RANGE

Citation Formats

Liu, B., Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Toro, M. Di, Greco, V., University of Catania, I-95123 Catania, Shen, C. W., School of Science, Huzhou Teachers College, Huzhou 313000, Zhao, E. G., and Sun, B. X.. Application of density dependent parametrization models to asymmetric nuclear matter. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.048801.
Liu, B., Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Toro, M. Di, Greco, V., University of Catania, I-95123 Catania, Shen, C. W., School of Science, Huzhou Teachers College, Huzhou 313000, Zhao, E. G., & Sun, B. X.. Application of density dependent parametrization models to asymmetric nuclear matter. United States. doi:10.1103/PHYSREVC.75.048801.
Liu, B., Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Toro, M. Di, Greco, V., University of Catania, I-95123 Catania, Shen, C. W., School of Science, Huzhou Teachers College, Huzhou 313000, Zhao, E. G., and Sun, B. X.. Sun . "Application of density dependent parametrization models to asymmetric nuclear matter". United States. doi:10.1103/PHYSREVC.75.048801.
@article{osti_20995251,
title = {Application of density dependent parametrization models to asymmetric nuclear matter},
author = {Liu, B. and Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 and Toro, M. Di and Greco, V. and University of Catania, I-95123 Catania and Shen, C. W. and School of Science, Huzhou Teachers College, Huzhou 313000 and Zhao, E. G. and Sun, B. X.},
abstractNote = {Density dependent parametrization models of the nucleon-meson effective couplings, including the isovector scalar {delta}-field, are applied to asymmetric nuclear matter. The nuclear equation of state and the neutron star properties are studied in an effective Lagrangian density approach, using the relativistic mean field hadron theory. It is known that the introduction of a {delta}-meson in the constant coupling scheme leads to an increase of the symmetry energy at high density and so to larger neutron star masses, in a pure nucleon-lepton scheme. We use here a more microscopic density dependent model of the nucleon-meson couplings to study the properties of neutron star matter and to reexamine the {delta}-field effects in asymmetric nuclear matter. Our calculations show that, due to the increase of the effective {delta} coupling at high density, with density dependent couplings the neutron star masses in fact can be even reduced.},
doi = {10.1103/PHYSREVC.75.048801},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 75,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • Using various relativistic mean-field models, including nonlinear ones with meson field self-interactions, models with density-dependent meson-nucleon couplings, and point-coupling models without meson fields, we have studied the isospin-dependent bulk and single-particle properties of asymmetric nuclear matter. In particular, we have determined the density dependence of nuclear symmetry energy from these different relativistic mean-field models and compared the results with the constraints recently extracted from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate energy heavy-ion collisions as well as from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes. Among the 23 parameter setsmore » in the relativistic mean-field model that are commonly used for nuclear structure studies, only a few are found to give symmetry energies that are consistent with the empirical constraints. We have also studied the nuclear symmetry potential and the isospin splitting of the nucleon effective mass in isospin asymmetric nuclear matter. We find that both the momentum dependence of the nuclear symmetry potential at fixed baryon density and the isospin splitting of the nucleon effective mass in neutron-rich nuclear matter depend not only on the nuclear interactions but also on the definition of the nucleon optical potential.« less
  • Thermal properties of asymmetric nuclear matter are studied within a self-consistent thermal model using an isospin and momentum-dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, a momentum-independent interaction (MID), and an isoscalar momentum-dependent interaction (eMDYI). In particular, we study the temperature dependence of the isospin-dependent bulk and single-particle properties, the mechanical and chemical instabilities, and liquid-gas phase transition in hot asymmetric nuclear matter. Our results indicate that the temperature dependence of the equation of state and the symmetry energy are not so sensitive to the momentum dependence of the interaction. The symmetry energy at fixed densitymore » is found to generally decrease with temperature and for the MDI interaction the decrement is essentially due to the potential part. It is further shown that only the low momentum part of the single-particle potential and the nucleon effective mass increases significantly with temperature for the momentum-dependent interactions. For the MDI interaction, the low momentum part of the symmetry potential is significantly reduced with increasing temperature. For the mechanical and chemical instabilities as well as the liquid-gas phase transition in hot asymmetric nuclear matter, our results indicate that the boundaries of these instabilities and the phase-coexistence region generally shrink with increasing temperature and are sensitive to the density dependence of the symmetry energy and the isospin and momentum dependence of the nuclear interaction, especially at higher temperatures.« less
  • The density dependence of nuclear symmetry energy is determined from a systematic study of the isospin dependent bulk properties of asymmetric nuclear matter using the isoscalar and isovector components of the density dependent M3Y interaction. The incompressibility K{sub {infinity}} for the symmetric nuclear matter, the isospin dependent part K{sub asy} of the isobaric incompressibility, and the slope L are all in excellent agreement with the constraints recently extracted from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes, from the neutron skin thickness of nuclei, and from analyses of experimental data on isospin diffusion and isotopic scalingmore » in intermediate energy heavy-ion collisions. This work provides a fundamental basis for the understanding of nuclear matter under extreme conditions and validates the important empirical constraints obtained from recent experimental data.« less
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