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Energy Level Statistics of the U(5) and O(6) Symmetries in the Interacting Boson Model

Jing Shu; Ying Ran; Tao Ji; Yu-xin LiuSubjects: Physics >> The Physics of Elementary Particles and Fields

We study the energy level statistics of the states in U(5) and O(6) dynamical symmetries of the interacting boson model and the high spin states with backbending in U(5) symmetry. In the calculations, the degeneracy resulting from the additional quantum number is eliminated manually. The calculated results indicate that the finite boson number N effect is prominent. When N has a value close to a realistic one, increasing the interaction strength of subgroup O(5) makes the statistics vary from Poisson-type to GOE-type and further recover to Poisson-type. |

Statistical Properties of E(5) and X(5) Symmetries

Jing Shu; Hong-bo Jia; Yu-xin LiuSubjects: Physics >> The Physics of Elementary Particles and Fields

We study the energy level statistics of the states in E(5) and X(5) dynamical symmetries. The calculated results indicate that the statistics of E(5) symmetry is regular and follows Poisson statistics, while that of X(5) symmetry involves two maxima in the nearest neighbor level spacing distribution P(s) and the ?3 statistics follows the GOE statistics. It provides an evidence that the X(5) symmetry is at the critical point exhibiting competing degrees of freedom |

Spherical Relativistic Hartree theory in a Woods-Saxon basis

Shan-Gui Zhou Jie Meng P. RingSubjects: Physics >> Nuclear Physics

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. |

Spin symmetry in the anti-nucleon spectrum

Shan-Gui Zhou Jie Meng P. RingSubjects: Physics >> Nuclear Physics

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. |

D? (2317)+ : a P state from the light cone harmonic oscillator model?

han-Gui Zhou; Hans-Christian PauliSubjects: Physics >> Nuclear Physics

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. |

Subjects: Physics >> Nuclear Physics

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. |

Subjects: Physics >> Nuclear Physics

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. |

Subjects: Physics >> Nuclear Physics

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. |

Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei

J. Meng; H. Toki; S. G. Zhou; S. Q. Zhang; W. H. Long; L. S. GengSubjects: Physics >> Nuclear Physics

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. |

Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei

J. Meng; H. Toki; S. G. Zhou; S. Q. Zhang; W. H. Long; L. S. GengSubjects: Physics >> Nuclear Physics

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. |