分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The ground state properties including radii, density distribution and one neutron separation energy for C, N, O and F isotopes up to the neutron drip line are systematically studied by the fully self-consistent microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton density distribution thus obtained, the charge-changing cross sections for C, N, O and F isotopes are calculated using the Glauber model. Good agreement with the data has been achieved. The charge changing cross sections change only slightly with the neutron number except for proton-rich nuclei. Similar trends of variations of proton radii and of charge changing cross sections for each isotope chain is observed which implies that the proton density plays important role in determining the charge-changing cross sections.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: Based on the systematic investigation of the data available for A ≥ 40, a Z1/3 dependence for the nuclear charge radii is shown to be superior to the generally accepted A1/3 law. A delicate scattering of data around Rc/Z1/3 is infered as owing to the isospin effect and a linear dependence of Rc/Z1/3 on N/Z ( or (N − Z)/2 ) is found. This inference is well supported by the microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) calculation conducted for the proton magic Ca, Ni, Zr, Sn and Pb isotopes including the exotic nuclei close to the neutron drip line. With the linear isospin dependence provided by the data and RCHB theory, a new isospin dependent Z1/3 formula for the nuclear charge radii is proposed.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The origin of pseudospin symmetry and its broken in real nuclei are discussed in the relativistic mean field theory. In the exact pseudospin symmetry, even the usual intruder orbits have degenerate partners. In real nuclei, pseudospin symme- try is approximate, and the partners of the usual intruder orbits will disappear. The difference is mainly due to the pseudo spin-orbit potential and the transition between them is discussed in details. The contribution of pseudospin-orbit potential for intruder orbits is quite large, compared with that for pseudospin doublets. The disappearance of the pseu- dospin partner for the intruder orbit can be understood from the properties of its wave function.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We show that the splitting between the light pseudo-scalar and vector meson states is due to the strong short-range attraction in the 1S0 sector which makes the pion and the kaon light particles. We use a light-cone QCD-inspired model of the mass squared operator with harmonic confinement and a Dirac-delta interaction. We apply a renormalization method to define the model, in which the pseudo-scalar ground state mass fixes the renormalized strength of the Dirac-delta interaction.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: A light-cone QCD-inspired model, with the mass squared operator consisting of a harmonic oscillator potential as confinement and a Dirac-delta interac- tion, is used to study the S-wave meson spectra. The two parameters of the harmonic potential and quark masses are fixed by masses of ρ(770), ρ(1450), J/ψ, ψ(2S), K∗(892) and B∗. We apply a renormalization method to define the model, in which the pseudo-scalar ground state mass fixes the renormal- ized strength of the Dirac-delta interaction. The model presents an universal and satisfactory description of both singlet and triplet states of S-wave mesons and the corresponding radial excitations.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We study the proton magic O, Ca, Ni, Zr, Sn, and Pb isotope chains from the proton drip line to the neutron drip line with the relativistic con- tinuum Hartree-Bogoliubov (RCHB) theory. Particulary, we study in detail the properties of even-even Ca isotopes due to the appearance of giant ha- los in neutron rich Ca nuclei near the neutron drip line. The RCHB theory is able to reproduce the experimental binding energies Eb and two neutron separation energies S2n very well. The predicted neutron drip line nuclei are 28O, 72Ca, 98Ni, 136Zr, 176Sn, and 266Pb, respectively. Halo and giant halo properties predicted in Ca isotopes with A > 60 are investigated in detail from the analysis of two neutron separation energies, nucleon density distri- butions, single particle energy levels, the occupation probabilities of energy levels including continuum states. The spin-orbit splitting and the diffuseness of nuclear potential in these Ca isotopes are studied also. Furthermore, we study the neighboring lighter isotopes in the drip line Ca region and find some possibility of giant halo nuclei in the Ne-Na-Mg drip line nuclei.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The Woods-Saxon basis has been suggested to replace the widely used harmonic oscillator basis for solving the relativistic mean field (RMF) theory in order to generalize it to study exotic nuclei. As examples, relativistic Hartree theory is solved for spherical nuclei in a Woods-Saxon basis obtained by solving either the Schro ̈dinger equation or the Dirac equation (labelled as SRHSWS and SRHDWS, respectively and SRHWS for both). In SRHDWS, the negative levels in the Dirac Sea must be properly included. The basis in SRHDWS could be smaller than that in SRHSWS which will simplify the deformed problem. The results from SRHWS are compared in detail with those from solving the spherical relativistic Hartree theory in the harmonic oscillator basis (SRHHO) and those in the coordinate space (SRHR). All of these approaches give identical nuclear properties such as total binding energies and root mean square radii for stable nuclei. For exotic nuclei, e.g., 72Ca, SRHWS satisfactorily reproduces the neutron density distribution from SRHR, while SRHHO fails. It is shown that the Woods-Saxon basis can be extended to more complicated situations for exotic nuclei where both deformation and pairing have to be taken into account.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We discuss spin and pseudo-spin symmetry in the spectrum of single nucleons and single anti- nucleons in a nucleus. As an example we use relativistic mean field theory to investigate single anti-nucleon spectra. We find a very well developed spin symmetry in single anti-neutron and single anti-proton spectra. The dominant components of the wave functions of the spin doublet are almost identical. This spin symmetry in anti-particle spectra and the pseudo-spin symmetry in particle spectra have the same origin. However it turns out that the spin symmetry in anti-nucleon spectra is much better developed than the pseudo-spin symmetry in normal nuclear single particle spectra.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We show that the mass of the recently found meson, Ds∗J(2317)+ could be reproduced by an effective light cone Hamiltonian model with a harmonic oscillator potential as confinement — the light cone harmonic oscillator model.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: I present some recent applications of a light cone QCD-inspired model with the mass squared operator consisting of a harmonic oscillator potential as con- finement in the meson spectra. The model gives an universal and satisfactory description of both singlet and triplet states of S-wave mesons. In the present work P -wave Ds mesons are also investigated. The mass of the recently found meson, Ds∗J (2317)+ is reproduced fairly well by this simple model.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: New parameter sets for the Lagrangian density in the relativistic mean field (RMF) theory, PK1 with nonlinear σ- and ω-meson self-coupling, PK1R with nonlinear σ-, ω- and ρ-meson self-coupling and PKDD with the density-dependent meson-nucleon coupling, are proposed. They are able to provide an excellent description not only for the properties of nuclear matter but also for the nuclei in and far from the valley of beta-stability. For the first time in the parametrization of the RMF Lagrangian density, the center-of-mass correction is treated by a microscopic way, which is essential to unify the description of nuclei from light to heavy regions with one effective interaction.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We use a light cone harmonic oscillator model to study S wave meson spectra, namely the pseu- doscalar and vector mesons. The model Hamiltonian is a mass squared operator consisting of a central potential (a harmonic oscillator potential) from which a hyperfine interaction is derived. The hyperfine interaction is responsible for the splitting in the pseudoscalar-vector spectra. With 4 parameters for the masses of up/down, strange, charm and bottom quarks, 2 for the harmonic oscil- lator potential and 1 for the hyperfine interaction, the model presents a reasonably good agreement with the data.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigen- functions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calcu- lations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The critical point nuclei in Sm isotopes, which marks the first order phase transition between spherical U(5) and axially deformed shapes SU(3), have been investigated in the microscopic quadrupole constrained relativistic mean field (RMF) model plus BCS method with all the most used interactions, i.e., NL1, NL3, NLSH and TM1. The calculated potential energy surfaces show a clear shape transition for the even-even Sm isotopes with N = 82 ∼ 96 and the critical point nuclei are found to be 148Sm, 150Sm and 152Sm. Similar conclusions can also be drawn from the microscopic neutron and proton single particle spectra.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: Single-particle resonant states in spherical nuclei are studied by an analytic continuation in the coupling constant (ACCC) method within the framework of the self-consistent relativistic mean field (RMF) theory. Taking the neutron resonant state ν1g9/2 in 60Ca as an example, we examine the analyticity of the eigenvalue and eigenfunction for the Dirac equation with respect to the coupling constant by means of a Pad ́e approximant of the second kind. The RMF-ACCC approach is then applied to 122Zr and, for the first time, this approach is employed to investigate both the energies, widths and wave functions for l ̸= 0 resonant states close to the continuum threshold. Predictions are also compared with corresponding results obtained from the scattering phase shift method.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly takes into account the pairing correlation and the coupling to (discretized) continuum via Bogoliubov transformation in a micro- scopic and self-consistent way, has been reviewed together with its new interpretation of the halo phenomena observed in light nuclei as the scattering of particle pairs into the continuum, the prediction of the exotic phenomena — giant halos in nuclei near neutron drip line, the reproduction of interaction cross sections and charge-changing cross sections in light exotic nuclei in combination with the Glauber theory, better restora- tion of pseudospin symmetry in exotic nuclei, predictions of exotic phenomena in hyper nuclei, and new magic numbers in superheavy nuclei, etc. Recent investigations on new effective interactions, the density dependence of the interaction strengthes, the RMF theory on the Woods-Saxon basis, the single particle resonant states, and the resonant BCS (rBCS) method for the pairing correlation, etc. are also presented in some details.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly takes into account the pairing correlation and the coupling to (discretized) continuum via Bogoliubov transformation in a micro- scopic and self-consistent way, has been reviewed together with its new interpretation of the halo phenomena observed in light nuclei as the scattering of particle pairs into the continuum, the prediction of the exotic phenomena — giant halos in nuclei near neutron drip line, the reproduction of interaction cross sections and charge-changing cross sections in light exotic nuclei in combination with the Glauber theory, better restora- tion of pseudospin symmetry in exotic nuclei, predictions of exotic phenomena in hyper nuclei, and new magic numbers in superheavy nuclei, etc. Recent investigations on new effective interactions, the density dependence of the interaction strengthes, the RMF theory on the Woods-Saxon basis, the single particle resonant states, and the resonant BCS (rBCS) method for the pairing correlation, etc. are also presented in some details.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: Adiabatic and configuration-fixed constraint triaxial relativistic mean field (RMF) approaches are developed for the first time and a new phenomenon, the existence of multi-chiral doublets (MχD), i.e., more than one pairs of chiral doublets bands in one single nucleus, is suggested for 106Rh based on the triaxial deformations together with their corresponding proton and neutron configurations.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: The phenomena of giant halo and halo of neutron-rich even-Ca isotopes are investigated and compared in the framework of the relativistic continuum Hartree-Bogoliubov (RCHB) and non- relativistic Skyrme Hartree-Fock-Bogoliubov (HFB) calculations. With two parameter sets for each of the RCHB and the Skyrme HFB calculations, it is found that although halo phenomena exist for Ca isotopes near neutron drip line in both calculations, the halo of the Skyrme HFB calculations starts at a more neutron-rich nucleus than that of the RCHB calculations, and the RCHB calculations have larger neutron root-mean-square (rms) radii systematically in N ≥ 40 than those of the Skyrme HFB calculations. The former difference comes from difference in shell structure. The reasons for the latter can be partly explained by the neutron 3s1/2 orbit, which causes more than 50 % of the difference among the four calculations for neutron rms radii at 66Ca.
分类: 物理学 >> 核物理学 提交时间: 2017-08-22
摘要: We develop the real stabilization method within the framework of the relativistic mean field (RMF) model. With the self-consistent nuclear potentials from the RMF model, the real stabilization method is used to study single-particle resonant states in spherical nuclei. As examples, the energies, widths and wave functions of low-lying neutron resonant states in 120Sn are obtained. These results are compared with those from the scattering phase shift method and the analytic continuation in the coupling constant approach and satisfactory agreements are found.