arXiv subjects

K. C. Chung

Publications and source records attributed to K. C. Chung.

5 recordsLinked to original sources

arXiv2001

Extraction of nuclear matter properties from nuclear masses by a model of equation of state

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei. It is shown that the volume energy $a_1$ and the nuclear incompressibility $K_0$ depend essentially on $μ_n N+\barμ_p Z-2E_N$, whereas the symmetry energy $J$ and the density symmetry coefficient $L$ as well as symmetry incompressibility $K_s$ depend essentially on $μ_n-\barμ_p$, where $\barμ_p=μ_p-\partial E_C/\partial Z$, $μ_n$ and $μ_p$ are the neutron and proton chemical potentials respectively, $E_N$ the nuclear energy, and $E_C$ the Coulomb energy. The obtained symmetry energy is $J=28.5MeV$, while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.

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arXiv2001

Effective nucleon mass in relativistic mean field theory

In the $σ$-$ω$-$ρ$ model of the relativistic mean field theory with nonlinear $σ$-meson self-interaction, the effective nucleon mass $M^*$ is discussed with relation to the symmetry incompressibility $K_s$ of nuclear matter, based on the model parameters fitted to nuclear matter properties. It is shown that $M^*$ is larger than $0.73M$, if $K_s$ is assumed to be negative and the nuclear matter incompressibility $K_0$ is kept less than $300 MeV$. Furthermore, the field system is shown to be stable, as the $σ$-meson self-interaction energy is lower bounded in this parameter region.

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arXiv2001

Nuclear matter properties and relativistic mean-field theory

Nuclear matter properties are calculated in the relativistic mean field theory by using a number of different parameter sets. The result shows that the volume energy $a_1$ and the symmetry energy $J$ are around the acceptable values 16MeV and 30MeV respectively; the incompressibility $K_0$ is unacceptably high in the linear model, but assumes reasonable value if nonlinear terms are included; the density symmetry $L$ is around $100MeV$ for most parameter sets, and the symmetry incompressibility $K_s$ has positive sign which is opposite to expectations based on the nonrelativistic model. In almost all parameter sets there exists a critical point $(ρ_c, δ_c)$, where the minimum and the maximum of the equation of state are coincident and the incompressibility equals zero, falling into ranges 0.014fm$^{-3}<ρ_c<0.039$fm$^{-3}$ and $0.74<δ_c\le0.95$; for a few parameter sets there is no critical point and the pure neutron matter is predicted to be bound. The maximum mass $M_{NS}$ of neutron stars is predicted in the range 2.45M$_\odot\leq M_{NS}\leq 3.26$M$_\odot$, the corresponding neutron star radius $R_{NS}$ is in the range 12.2km$\leq R_{NS}\leq 15.1$km.

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arXiv2001

Effective nucleon-nucleon interactions and nuclear matter equation of state

Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and Tondeur interactions are written as polynomials of the cubic root of density, with coefficients that are functions of the relative neutron excess $δ$. In the extrapolation toward states far away from the standard one, it is shown that the asymmetry dependence of the critical point ($ρ_c, δ_c$) depends on the model used. However, when the equations of state are fitted to the same standard state, the value of $δ_c$ is almost the same in Skyrme and in Myers-Swiatecki interactions, while is much lower in Tondeur interaction. Furthermore, $δ_c$ does not depend sensitively on the choice of the parameter $γ$ in Skyrme interaction.

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arXiv2000

Nuclear matter properties in the relativistic mean field model with sigma-omega coupling

The possibility of extending the linear sigma-omega model by introducing a sigma-omega coupling phenomenologically is explored. It is shown that, in contrast to the usual Walecka model, not only the effective nucleon mass M* but also the effective sigma meson mass m*_sigma and the effective omega meson mass m*_omega are nucleon density dependent. When the model parameters are fitted to the nuclear saturation point (the nuclear radius constant r_0=1.14fm and volume energy a_1=16.0MeV) as well as to the effective nucleon mass M*=0.85M, the model yields m*_sigma=1.09m_sigma and m*_omega=0.90m_omega at the saturation point, and the nuclear incompressibility K_0=501MeV. The lowest value of K_0 given by this model by adjusting the model parameters is around 227MeV.

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