Temperature Effects on the Equation of State and Symmetry Energy at Low and High Densities
- PDF / 1,231,320 Bytes
- 13 Pages / 612 x 792 pts (letter) Page_size
- 37 Downloads / 172 Views
NUCLEI Theory
Temperature Effects on the Equation of State and Symmetry Energy at Low and High Densities∗ Kh. Gad1), 2)** Received February 1, 2018
Abstract—Thermal properties of symmetric nuclear matter and pure neutron matter are studied in a selfconsistent Green’s function and Brueckner–Hartree–Fock approaches with the inclusion of the contact interaction using CDBONN potential. Also we investigate the temperature dependence of the symmetry energy. The symmetry energy at fixed density is found to generally decrease with temperature. The temperature effects on the nuclear matter symmetry energy are found to be stronger at lower densities while become much weaker at higher densities. The results of several microscopic approaches are compared. Also the results are compared with recent experimental data. There is good agreement between the experimental symmetry energy and those calculated in the Brueckner–Hartree–Fock approach. DOI: 10.1134/S1063778818040038
1. INTRODUCTION One of the most fundamental issues in theoretical nuclear physics is the understanding of nuclear matter under high density and/or high temperature. At very high density and temperature there is a possibility of quark-gluon plasma creation. Studying nuclear matter is very important to understand the structure of neutron stars [1–3]. The nuclear equation of state for finite temperatures [4–7] is necessary for studies of many processes, e.g. core collapse of supernovae (SN), black hole formation and neutron star cooling, to name but a few. Also knowledge of the equation of states (EOS) of pure neutron matter at high densities is the important bridge between the symmetry energy in nuclei and the neutron star properties. Neutron stars have become more important in recent years. The discovery of the first two-solar-mass neutron stars with twice solar mass [8, 9] provided critical constraints on the dense matter equation of state, and many models yielding the soft equation of states were excluded. Information about the EOS is essential in understanding not only many aspects of nuclear physics, but also a number of important issues in astrophysics [10–14]. Several approaches have been developed to study the EOS of nuclear matter including variational ∗
The text was submitted by the author in English. Physics Department, Faculty of Science, Islamic University, Al-Madina, KSA. 2) Physics Department, Faculty of Science, Sohag University, Sohag 82524, Egypt. ** E-mail: [email protected] 1)
techniques within the correlated basis functions [1], quantum Monte Carlo [15] or more recently the auxiliary field diffusion Monte Carlo [16, 17]. Many efforts have been also devoted to the traditional BruecknerBethe–Goldstone hole-line expansion [18] in its lowest-order form, the so called Brueckner–Hartree– Fock (Exact-BHF) approximation [19]. The strong short-range repulsion prevents the use of perturbative expansions and either one incorporates explicitly the correlations in the wave function, as it is the case of the variational approaches, or performs partial summatio
Data Loading...
