Asymmetric nuclear matter and realistic potentials
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ORIGINAL PAPER
Asymmetric nuclear matter and realistic potentials Kh Gad1,2* 1
Physics Department, Faculty of Science, Islamic University of Madinah, Madinah, Kingdom of Saudi Arabia 2
Physics Department, Faculty of Science, Sohag University, Sohag 82524, Egypt Received: 28 September 2019 / Accepted: 24 February 2020
Abstract: The equation of state for asymmetric nuclear matter is presented within the Brueckner–Hartree–Fock (BHF) approach by using recent high-quality soft nucleon–nucleon potentials from next-to-leading order (NLO) up to fifth order (N4LO) of the chiral expansion for the wide range of densities and asymmetry parameter, which are very interesting these days in the heavy-ion collisions and neutron stars. For comparison purposes, the same calculations are performed for Brueckner–Hartree–Fock approach plus two-body density-dependent Skyrme potential which is equivalent to three-body forces. Also the results are compared with the other theoretical models, especially the Brueckner–Hartree–Fock plus threebody forces and the Dirac–Brueckner–Hartree–Fock approaches. Our equation-of-state models are able to reproduce the empirical symmetry energy Esym and its slope parameter L at the empirical saturation density q0 and are compatible with experimental data from collisions between heavy nuclei. The symmetry energy of about 30 MeV is obtained at the saturation nuclear matter density. There is very good agreement between the experimental symmetry energy value and those calculated in the Brueckner–Hartree–Fock approach. Keywords: Asymmetric nuclear matter; Brueckner–Hartree–Fock approximation; Equation of state; Skyrme interaction; Chiral effective field theory
1. Introduction The properties of asymmetric nuclear matter (ANM) are important for addressing a number of open questions in nuclear physics and nuclear astrophysics, including the location on neutron drip lines, the thickness on neutron skins, and the structure of neutron stars [1–12]. The structure of neutron stars is strongly sensitive to the equation of state (EoS) of cold, fully catalyzed, asymmetric nuclear matter (ANM) over an enormous range of densities [13–15]. So it is very interesting to predict EoS by a full microscopic many-body calculation. Also new data from heavy-ion collisions can be used to extract the free symmetry energy. The symmetry energy and its density dependence are therefore a key focus of contemporary theoretical and experimental investigations, and much effort has been devoted to finding correlations between nuclear observables and this property of infinite nuclear matter. Recently developed quantum statistical approach
*Corresponding author, E-mail: [email protected]
that takes into account the formation of clusters predicts symmetry energies that are in very good agreement with the experimental data. Two recent studies [16, 17] provide indications for how the overbinding energy problem may be overcome. Numerous calculations have been performed by using different methods to solve the many-body problem of symmetric nuc
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