Nonlinear Relativistic Mean-field Theory Research Articles

Nonlinear relativistic mean-field theory studies on He isotopes

The ground state properties of He isotopes are studied in the nonlinear relativistic mean-field (RMF) theory with force parameters NL-SH and TM2. The modified Glauber model is introduced as a gatekeeper to check the calculations. The investigation shows that the RMF theory provides a good description on the properties of He isotopes. The many-body space information of 4He + neutrons is obtained reliably. As a product, the calculation gives strong evidence for a neutron halo in 5He.

Quark deconfinement in high-mass neutron stars

In this paper, we explore whether or not quark deconfinement may occur in high-mass neutron stars such as J1614 \ensuremath{-} 2230 ($1.97\ifmmode\pm\else\textpm\fi{}0.04\phantom{\rule{0.16em}{0ex}}{M}_{\ensuremath{\bigodot}}$) and J0348 + 0432 ($2.01\ifmmode\pm\else\textpm\fi{}0.04\phantom{\rule{0.16em}{0ex}}{M}_{\ensuremath{\bigodot}}$). Our study is based on a nonlocal extension of the SU(3) Nambu--Jona-Lasinio (n3NJL) model with repulsive vector interactions among the quarks. This model goes beyond the frequently used local version of the Nambu--Jona-Lasinio (NJL) model by accounting for several key features of QCD which are not part of the local model. Confined hadronic matter is treated in the framework of nonlinear relativistic mean field theory. We find that both the local as well as the nonlocal NJL model predict the existence of extended regions of mixed quark-hadron (quark-hybrid) matter in high-mass neutron stars with masses of 2.1 to $2.4\phantom{\rule{0.16em}{0ex}}{M}_{\ensuremath{\bigodot}}$. Pure quark matter in the cores of neutron stars is obtained for certain parametrizations of the hadronic lagrangian and choices of the vector repulsion among quarks. The radii of high-mass neutron stars with quark-hybrid matter and/or pure quark matter cores in their centers are found to lie in the canonical range of 12 to 13 km.

Neutron halos in the excited states for N = 127 isotones

Properties of the ground states and the excited states of N = 127 isotones are investigated by using the nonlinear relativistic mean field theory with the interactions PK1. By analyzing the rms of proton and neutron, the single particle energies of valence nucleon and the density distributions of neutron, proton and the last neutron, it can be found that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 209Pb. It is also predicted that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 207Hg, 208Tl, 210Bi and 211Po.

HALO IN THE EXCITED STATES FOR N = 41 ISOTONES

The properties of N = 41 isotones are investigated systemically by using the nonlinear relativistic mean field theory. It is found that all the calculating binding energies with four different interactions are comparable for the ground and low-lying excited states, and very close to the data available. The calculations show that there exists a neutron halo in the first excited state in 69 Ni , as well as in the second excited state in 69 Ni . It is also predicted that there exists a neutron halo in the first excited state in 65 Cr , 66 Mn , 67 Fe and 68 Co .

Halo or skin in the excited states of some light mirror nuclei

The properties of three pairs of mirror nuclei 13N- 13C, 15N- 15O and 21Na- 21Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2s1/2 excited states of 15N and of 21Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1d5/2 excited state of 13C and the 2s1/2 excited state of 15O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2s1/2 and 1d5/2 excited states of 13N are also discussed.

One Neutron Halo in a 12B Excited State

The nonlinear relativistic mean field (RMF) theory with a neweffective interaction NL3 has been used to investigate the bulkproperties of the 12B nucleus. The results obtained in the RMFpredict one neutron halo in a 12B excited state. 12Bdoes not show the neutron halo structure if it is in its groundstate.

Neutron halo state of13C

Angular distributions for the12C(d, p)13C transfer reactions have been measured at Ed = 11.8 MeV, and compared with those of the DWBA calculations. By means of this comparison, density distributions of the last neutron in the ground state and the first 1/2+ state of13C are extracted. The properties of these states in13C have also been studied in the framework of the nonlinear relativistic mean-field theory with NL-SH parameters. It is found that the first 1/2+ state in13C is a neutron halo state shown by both the experimental and theoretical density distributions of the last neutron.

One-Neutron Halos in N = 9 Isotones**The project supported by a fund of the China Education Committee and National Natural Science Foundation of China

We have studied the ground-state properties of N = 8 and N = 9 isotones in the framework of the nonlinear relativistic mean-field (RMF) theory using force parameters NL-SH. It is shown that the RMF theory provides a good description of the ground-state properties. One-neutron halos in 15C and 14B are predicted. A simple discussion on the level inversion in N = 9 isotones is given.

Level inversion of N=9 isotones in the relativistic mean-field theory

We have studied the ground state properties of N=8 and N=9 isotones in the framework of the nonlinear relativistic mean-field (RMF) theory using force parameters NL-SH. Calculations show that the RMF theory can describe experimental data of binding energies and radii for these nuclei. The RMF theory can also reproduce the level inversion of N=9 isotones well if the ρ tensor coupling is included. One-neutron halos in 15C and 14B are predicted.

Relativistic mean-field study of light proton-rich nuclei18Ne,20Mg and22Si

The ground state properties of proton-rich nuclei18Ne,20Mg and22Si have been investigated using the nonlinear relativistic mean-field theory with NL1 and NL-SH parameters. Proton halos in these nuclei are predicted. The characteristics of proton halos in nuclei are simply discussed.

Relativistic mean-field study of even - even nuclei near and

We have studied the ground state properties of even - even nuclei with proton number Z = 106 - 114 and neutron number N = 160 - 170 in the framework of the nonlinear relativistic mean-field theory. Calculations show that there are prolate deformations in these nuclei and this supports a deformed shape for nuclei near N = 162 predicted by macroscopic models. The calculated binding energies and -decay energies agree very well with those from mass models.

Relativistic mean-field study of Mg isotopes

The nonlinear relativistic mean-field theory is used to investigate the ground state properties of Mg isotopes from the proton-drip-line nucleus 20Mg to the neutron-drip-line nucleus 40Mg, covering three magic numbers N = 8, 20, and 28. Special emphasis is placed on the influence of the pairing correlation on the deformation. Calculations show that the relativistic mean-field theory provides a good description of the binding energy and the root-mean-square radius of charge distributions. A monotonic increase of the neutron skin thickness with neutron excess is predicted. The nuclear shell structure at magic numbers N = 8, 20, and 28 is discussed.

Relativistic mean-field study of exotic carbon nuclei

The structure of carbon isotopes from the proton-drip-line nucleus 9C to the neutron-drip-line nucleus 22C has been systematically studied in the framework of the nonlinear relativistic mean-field theory with inclusion of deformations. Calculations show that the relativistic mean-field theory provides a reasonably good description of experimental binding energies and root-mean-square radii. The spin and parity of the ground state in 15,17,19C are correctly predicted to be (12)+, (32)+ and (12)+, respectively. The effect of deformations on the structure of exotic nuclei is discussed and a consistent explanation on the one-neutron halo in 19C is given.

Isospin dependence of collective flow in heavy-ion collisions at intermediate energies.

Within the framework of an isospin-dependent Boltzmann-Uehling-Uhlenbeck (BUU) model using initial proton and neutron densities calculated from the nonlinear relativistic mean-field (RMF) theory, we compare the strength of transverse collective flow in reactions $^{48}Ca+^{58}Fe$ and $^{48}Cr+^{58}Ni$, which have the same mass number but different neutron/proton ratios. The neutron-rich system ($^{48}Ca+^{58}Fe$) is found to show significantly stronger negative deflection and consequently has a higher balance energy, especially in peripheral collisions. NOTE ADDED IN PROOF: The new phenomenon predicted in this work has just been confirmed by an experiment done by G.D. Westfall et al. using the NSCL/MSU radioactive beam facility and a spartan soccer. A paper by R. Pak et al. is submitted to PRL to report the experimental result.

One-neutron halos in and and three-neutron halo in

Study of the ground-state properties of and has been performed in the framework of the nonlinear relativistic mean-field (RMF) theory using force parameters NL-SH and NL1. It is shown that the RMF theory provide a good description of the binding energies. One-neutron halos in , and and a three-neutron halo in are predicted.

One-proton halo in 26P and two-proton halo in 27S.

Proton-drip-line nuclei {sup 26}P and {sup 27}S are studied in the nonlinear relativistic mean-field theory. Calculations show that the mean-square radius of protons in the 2{ital s}{sub 1/2} state is approximately 18{endash}20 fm{sup 2} which is abnormally large as compared with the mean-square radii of proton, neutron, and matter distributions, giving a strong evidence for proton halos in {sup 26}P and {sup 27}S. This indicates that the size of proton halos is as large as that of neutron halos although there exists the Coulomb barrier in proton-drip-line nuclei. {copyright} {ital 1996 The American Physical Society.}

Relativistic mean-field study of light neutron-rich nuclei

We study theoretically the ground state properties of N=8, N=20, and N=40 neutron-rich isotones using the nonlinear relativistic mean-field theory. It is found that the nonlinear relativistic mean-field theory can very satisfactorily reproduce the ground state properties of the above nuclei, even near the neutron drip line. Some relevant phenomena on nuclear structure have been discussed.

Neutron halos in O isotopes.

The ground state properties of O isotopes have been studied in the nonlinear relativistic mean-field theory with NL-SH parameters. Neutron halos in $^{24}\mathrm{O}$, $^{26}\mathrm{O}$, and $^{28}\mathrm{O}$ are predicted. The variation of the spin-orbit splitting with the neutron excess for O isotopes is also investigated with both NL-SH and NL1 parameters. Detailed comparison and analysis on the results are given.

Effective nucleon mass, incompressibility, and third derivative of nuclear binding energy in the nonlinear relativistic mean field theory.

We have studied the equations of state of nuclear matter using the nonlinear [sigma]-[omega] model. At the normal density, there is a strong correlation among the effective nucleon mass [ital M][sub 0][sup *], the incompressibility, [ital K] and the third derivative [ital K][prime] of binding energy. The results are compared with the empirical analysis of the giant isoscalar monopole resonances data. It is difficult to fit the data when [ital K][approx lt]200 MeV, using the model. It is also found that [ital K]=300[plus minus]50 MeV is favorable to account for the volume-symmetry properties of nuclear matter.

Nuclear equation of state from the nonlinear relativistic mean field theory.

The properties of symmetric nuclear matter are investigated in the nonlinear relativistic mean field theory of nuclear matter. We consider the constraints imposed by four nuclear ground state properties on the coupling constants and on the equation of state at zero and at finite temperature. We find that the compression constant K(${\ensuremath{\rho}}_{0}$) as well as the temperature is irrelevant for the stiffness of the equation of state for ${m}^{\mathrm{*}}$(${\ensuremath{\rho}}_{0}$)\ensuremath{\le}0.7. The main point is that the relativistic mean field theory exhibits acausal and unphysical behavior for compressibilities below K(${\ensuremath{\rho}}_{0}$)=200 MeV. Every set of coupling constants with a negative quartic coupling constant c is unstable against small quantum fluctuations.