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Pseudospin symmetry and its approximation in real nuclei

T.S. Chen; H.F. Lu; J. Meng; and S.-G. ZhouSubjects: Physics >> Nuclear Physics

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. |

Splitting of the π ? ρ spectrum in a renormalized light-cone QCD-inspired model

T. Frederico; Hans-Christian Pauli; Shan-Gui ZhouSubjects: Physics >> Nuclear Physics

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. |

Universal description of S-wave meson spectra in a renormalized light-cone QCD-inspired model

T. Frederico; Hans-Christian Pauli; Shan-Gui ZhouSubjects: Physics >> Nuclear Physics

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. |

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. |

MESON SPECTRA FROM AN EFFECTIVE LIGHT CONE QCD-INSPIRED MODEL

Shan-Gui ZhouSubjects: Physics >> Nuclear Physics

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. |

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. |

Test of Pseudospin Symmetry in Deformed Nuclei

J.N. Ginocchio; A. Leviatan; J. Meng; Shan-Gui ZhouSubjects: Physics >> Nuclear Physics

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. |

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. |