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1.
S. Marcos M. López-Quelle R. Niembro L. N. Savushkin 《The European Physical Journal A - Hadrons and Nuclei》2007,34(4):429-441
In the phenomenological relativistic framework of the Dirac equation for spherical nuclei, we use different kinds of single-particle
central potentials ( ΣS + Σ0 to investigate certain aspects of the spin and pseudospin (PS) symmetries. Neither the splitting of PS doublets (PSDs) nor
the similarity of the radial parts of the small components (F/r of the corresponding Dirac spinors have been found related with the magnitude of ΣS + Σ0 , in the sense predicted by several authors in the last decade. This conclusion is shown to be valid, in particular, for
a potential of Coulomb type. We give a simple explanation for the strong correlation established in the relativistic calculations
between the similarity of the radial parts of the big (small) components of the Dirac spinors of two spin (pseudospin) partners
and the number of their nodes. The direct effects of the so-called PS symmetry-breaking term (and its singularity point) on
the F functions of the PSDs are also analysed. 相似文献
2.
3.
Quaternion Dirac equation has been analyzed and its supersymmetrization has been discussed consistently. It has been shown
that the quaternion Dirac equation automatically describes the spin structure with its spin up and spin down components of
two component quaternion Dirac spinors associated with positive and negative energies. It has also been shown that the supersymmetrization
of quaternion Dirac equation works well for different cases associated with zero mass, nonzero mass, scalar potential and
generalized electromagnetic potentials. Accordingly we have discussed the splitting of supersymmetrized Dirac equation in
terms of electric and magnetic fields. 相似文献
4.
The effects of the symmetry breaking terms, spin-orbit potential (SOP) and pseudospin-orbit potential (PSOP), in the spin
and pseudospin symmetries, respectively, are studied in a comparative way. The analytical properties of the small component
F of the Dirac spinor for pseudospin doublets (PSDs) are investigated around the singularity point of the PSOP. We show that
the PSOP and the pseudocentrifugal barrier must be appropriately related to each other to describe adequately the wave functions
in the nuclear surface, whereas it is not the case for the centrifugal barrier and the SOP. We also determine a modified PSOP
smaller than the PSOP when the parameter ˉ, appearing in it, is left to vary in the domain of real numbers. The inclusion
of this modified PSOP allows us to define a continuous way that connects the two states of a PSD as ˉ varies continuously
between the physical (integer) values of ˉ corresponding to these states. Our results indicate that whereas the SOP can be
considered as a small spin symmetry breaking term that allows a simple explanation of the spin symmetry, the consideration
of the PSOP as the pseudospin symmetry breaking term presents serious difficulties. Thus, we propose a new strategy to explain,
in a simple way, the quasi-degeneracy of the PSDs. 相似文献
5.
One may ask whether the relations between energy and frequency and between momentum and wave vector, introduced for matter waves by de Broglie, are rigorously valid in the presence of gravity. In this paper, we show this to be true for Dirac equations in a background of gravitational and electromagnetic fields. We first transform any Dirac equation into an equivalent canonical form, sometimes used in particular cases to solve Dirac equations in a curved space-time. This canonical form is needed to apply Whitham’s Lagrangian method. The latter method, unlike the Wentzel–Kramers–Brillouin method, places no restriction on the magnitude of Planck’s constant to obtain wave packets and furthermore preserves the symmetries of the Dirac Lagrangian. We show by using canonical Dirac fields in a curved space-time that the probability current has a Gordon decomposition into a convection current and a spin current and that the spin current vanishes in the Whitham approximation, which explains the negligible effect of spin on wave packet solutions, independent of the size of Planck’s constant. We further discuss the classical-quantum correspondence in a curved space-time based on both Lagrangian and Hamiltonian formulations of the Whitham equations. We show that the generalized de Broglie relations in a curved space-time are a direct consequence of Whitham’s Lagrangian method and not just a physical hypothesis as introduced by Einstein and de Broglie and by many quantum mechanics textbooks. 相似文献
6.
求解了非球谐振子势场中1/2自旋粒子满足的Dirac方程,Dirac哈密顿量包含有标量非球谐振子势S(r)和矢量非球谐振子势V(r).在Σ(r)=S(r)+V(r)=0和Δ(r)=V(r)-S(r)=0的条件下,解析地得到了Dirac旋量波函数的束缚态解和能谱方程,结果表明非球谐振子势
关键词:
非球谐振子势
Dirac方程
赝自旋对称性
束缚态 相似文献
7.
E. Guliyev F. Ertuğral A. A. Kuliev 《The European Physical Journal A - Hadrons and Nuclei》2006,27(3):313-320
In this study the scissors mode 1+ states are systematically investigated within the rotational invariant Quasiparticle Random Phase Approximation (QRPA) for
130-136Ba isotopes. We consider the 1+ vibrations generated by the isovector spin-spin interactions and the isoscalar and isovector quadrupole-type separable forces
restoring the broken symmetry by a deformed mean field according to A.A. Kuliev et al. (Int. J. Mod. Phys. E 9, 249 (2000)). It has been shown that the restoration of the broken rotational symmetry of the Hamiltonian essentially decreases
the B(M1) value of the low-lying 1+ states and increases the collectivization of the scissors mode excitations in the spectroscopic energy region. The agreement
between the calculated mean excitation energies as well as the summed B(M1) value of the scissors mode excitations and the available experimental data of 134Ba and 136Ba is rather good. A destructive interference between the orbit and spin part of the M1 strength has been found for barium isotopes near the shell closer. For all the nuclei under investigation, the low-lying
M1 transitions have ΔK = 1 character as it is the case for the well-deformed nuclei. 相似文献
8.
A.A. Zvyagin A. Klümper J. Zittartz 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(1):25-36
The exactly solvable model of supersymmetric t - J chains (STJC) of correlated electrons with next-nearest-neighbour (NNN) interactions is proposed and studied. The model with
interactions between nearest neighbours and NNN interactions in one chain can also be considered as a two-chain model with
zigzag-like coupling between the chains. The NNN interaction (coupling between chains) causes the onset of additional Dirac
seas for low-lying charge and/or spin excitations. These Dirac seas change the low-energy (conformal) behavior of the model.
The filling of those seas depends on the values of the NNN coupling (interactions between chains), external magnetic field
and applied voltage. We identify the new ground state phases which appear due to the NNN as incommensurate ones. The NNN coupling
in the incommensurate phases induces spontaneous magnetization and/or spontaneous filling of the Dirac sea for charge excitations
(“spontaneous charge ordering”). The onset of this order implies a first order quantum phase transition driven by the field
with hysteresis phenomena.
Received 13 September 2000 相似文献
9.
I.I. Satija 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):345-348
Disordered systems exhibiting exponential localization are mapped to anisotropic spin chains with localization length being
related to the anisotropy of the spin model. This relates localization phenomenon in fermions to the rotational symmetry breaking
in the critical spin chains. One of the intriguing consequence is that the statement of Onsager universality in spin chains
implies universality of the localized fermions where the fluctuations in localized wave functions are universal. We further
show that the fluctuations about localized nonrelativistic fermions describe relativistic fermions. This provides a new approach
to understand the absence of localization in disordered Dirac fermions. We investigate how disorder affects well known universality
of the spin chains by examining the multifractal exponents. Finally, we examine the effects of correlations on the localization
characteristics of relativistic fermions.
Received 28 September 2001 / Received in final form 30 November 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: isatija@nickel.nist.gov 相似文献
10.
Taking ^120Sn as an example, we discuss the pseudospin symmetry in the single proton resonant states by examining the energies, widths and the wavefunctions. The information of the single proton resonant states in spherical nuclei are extracted from an analytic continuation in the coupling constant method within the framework of the self-consistent relativistic mean field theory under the relativistic boundary condition. We find small energy splitting in a pair of pseudospin partners in the resonant states. The lower components of the Dirac wavefunctions of a pseudospin doublet agree well in the region where nuclear potential dominates. It is concluded that the pseudospin symmetry is also well conserved for the resonant states in realistic nuclei. 相似文献
11.
In the presence of spin and pseudospin (p-spin) symmetries, the approximate analytical bound states of the Dirac equation for scalar-vector-tensor Hulthn potentials are obtained with any arbitrary spin-orbit coupling number κ using the Pekeris approximation. The Hulthn tensor interaction is studied instead of the commonly used Coulomb or linear terms. The generalized parametric Nikiforov-Uvarov (NU) method is used to obtain energy eigenvalues and corresponding wave functions in their closed forms. It is shown that tensor interaction removes degeneracy between spin and p-spin doublets. Some numerical results are also given. 相似文献
12.
D.A. Trifonov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):349-353
A survey on the generalizations of Heisenberg uncertainty relation and a general scheme for their entangled extensions to
several states and observables is presented. The scheme is illustrated on the examples of one and two states and canonical
quantum observables, and spin and quasi-spin components. Several new uncertainty relations are displayed.
Received 10 October 2001 / Received in final form 6 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: dtrif@inrne.bas.bg 相似文献
13.
The polarization effect on the spin symmetry for anti-Lambda spectrum in 16 O+Λ system has been studied in relativistic mean-field theory.The PK1 effective interaction is used for nucleon-meson couplings and G-parity symmetry with a reduction factor ξ = 0.3 is adopted for anti-Lambda-meson couplings.The energy differences between spin doublets in the anti-Lambda spectrum are around 0.10-0.73 MeV for p Λ state.The dominant components of the Dirac spinor for the anti-Lambda spin doublets are found to be near identical.It indicates that the spin symmetry is still well-conserved against the polarization effect from the valence antiLambda hyperon,which leads to a highly compressed cold nucleus with the central density up to 2 - 3 times of saturated density. 相似文献
14.
The g-factors of the positive parity rotational states up to spin I = 8^+ for the ground state band in even-even nuclei S2Sr have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The experimentally measured 9-factors increase with the increasing spin along the band and show that the g9/2 proton aligns only and the alignment starts from I =6^+. The measured g-factors also indicate that the nuclei ^82Sr gain their spins by the quasi-proton alignment at higher spin. 相似文献
15.
Haozhao Liang Wen Hui Long Jie Meng Nguyen Van Giai 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):119-124
The spin symmetry in the Dirac negative-energy spectrum and its origin are investigated for the first time within the density-dependent
relativistic Hartree-Fock (DDRHF) theory. Taking the nucleus 16O as an example, the spin symmetry in the negative-energy spectrum is found to be a good approximation and the dominant components
of the Dirac wave functions for the spin doublets are nearly identical. In comparison with the relativistic Hartree approximation
where the origin of spin symmetry lies in the equality of the scalar and vector potentials, in DDRHF the cancellation between
the Hartree and Fock terms is responsible for the better spin symmetry properties and determines the subtle spin-orbit splitting.
These conclusions hold even in the case when significant deviations from the G -parity values of the meson-antinucleon couplings occur. 相似文献
16.
The problem of uniqueness of spin operators for Dirac particles is examined. To this end, invariant spin relations based on
the spin projection in the rest frame are constructed.
Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 7–11, 1999. 相似文献
17.
We investigate the causal structure of two-sheeted space-times using the tools of Lorentzian spectral triples. We show that the noncommutative geometry of these spaces allows for causal relations between the two sheets. The computation is given in detail when the sheet is a 2- or 4-dimensional globally hyperbolic spin manifold. The conclusions are then generalised to a point-dependent distance between the two sheets resulting from the fluctuations of the Dirac operator. 相似文献
18.
We investigate the exact solution of the Dirac equation for the Mie-type potentials under the conditions of pseudospin and spin symmetry limits. The bound state energy equations and the corresponding two-component spinor wave functions of the Dirac particles for the Mie-type potentials with pseudospin and spin symmetry are obtained. We use the asymptotic iteration method in the calculations. Closed forms of the energy eigenvalues are obtained for any spin-orbit coupling term κ. We also investigate the energy eigenvalues of the Dirac particles for the well-known Kratzer-Fues and modified Kratzer potentials which are Mie-type potentials. 相似文献
19.
Hawking radiation of Klein-Gordon and Dirac particles in a non-stationary Kerr-Newman-de-Sitter black hole is studied by introducing a new tortoise coordinate transformation. The result shows that the Fermi-Dirac radiant spectrum displays a new term that represents the interaction between the spin of spinor particles and the rotation of black holes, which is absent in the Bose-Einstein distribution of Klein-Gordon particles. 相似文献
20.
Thomas Guhr 《Annals of Physics》2007,322(2):287-314
We identify three semiclassical parameters in the QCD Dirac operator. Mutual coupling of the different types of degrees of freedom (translational, colour and spin) depends on how the semiclassical limit is taken. We discuss various semiclassical limits and their potential to describe spectrum and spectral statistics of the QCD Dirac operator close to zero virtuality. 相似文献