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1.
The pseudospin symmetry (PSS) is an important feature of the nuclear structure. Most of the authors working in this field
at present consider the PSS as an approximate symmetry, although there exist certain essential differences in opinions about
the particularities of its realization. We have shown that the PSS in the nucleus is strongly related to the spin-orbit interaction
and, consequently, to the spin symmetry (SS). We conclude that the PSS, as well as the SS, can be studied appropriately in
the framework of the relativistic formalism.
The text was submitted by the authors in English. 相似文献
2.
S. Marcos M. López-Quelle R. Niembro L.N. Savushkin P. Bernardos 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):173-180
The reliability of the pseudospin symmetry (PSS) in atomic nuclei is analyzed in the framework of the relativistic Hartree
approach. We find that the nuclear surface strongly increases the effect of the pseudospin-orbit potential (PSOP), spoiling
the possibility of the exact realization of the PSS even in the limit of a vanishing PSOP. It is also shown that the PSS cannot
be explained by the fact that ΣS ≃ - Σ. New arguments to explain the PSS in finite nuclei are given. The important role the spin-orbit interaction plays in
the achievement of the PSS is also discussed.
Received: 22 July 2002 / Accepted: 18 February 2003 / Published online: 20 May 2003 相似文献
3.
We present a systematic investigation of the effect of spin-orbit interaction on optical conductivity in monolayer graphene. Our key findings are: (i) level splitting at various crystal symmetry points caused by true spin as well as pseudospin of the electrons gives rise to a resonant current response; (ii) under heavy doping, the spin-orbit interaction leads to a re-entrance of finite conductivity at very low frequency which was strictly forbidden in the absence of spin-orbit coupling; (iii) deformation of band structure and the topological properties of trigonal warping are analytically identified in a low-energy conical-like approximation. 相似文献
4.
The grounds on which the nuclear pseudospin symmetry (PSS) is supposed to be based are analysed within the relativistic mean-field framework. A connection between the mechanisms responsible for the spin-orbit and pseudospin-orbit splittings is shown. The nature of the PSS is investigated through an extended Dirac equation which allows a generalization of the PSS breaking term. It is shown that the PSS breaking in real nuclei can be explained as a result of a non-perturbative transformation from non-physical solutions of the Dirac equation, which satisfy exactly the PSS, to the physical ones. The PSS breaking term produces important, though qualitatively similar, effects on both states of a pseudospin-orbit doublet. The similarity of these effects increases with the number of nodes of the small component of the Dirac spinor of these states.Received: 28 April 2003, Revised: 30 October 2003, Published online: 18 June 2004PACS:
24.10.Jv Relativistic models - 21.60.Cs Shell model - 21.10.Pc Single-particle levels and strength functions - 24.80. + y Nuclear tests of fundamental interactions and symmetries 相似文献
5.
In this paper, by applying the Pekeris approximation, we present solutions of the Dirac equation for the Morse potential including a Coulomb-like tensor potential with arbitrary spin-orbit coupling number κ under spin and pseudospin symmetry limits. The generalized parametric Nikiforov–Uvarov method is used to obtain energy eigenvalues and corresponding eigenfunctions in their closed forms. We show that tensor interaction removes degeneracies between spin and pseudospin doublets. Some numerical results are given, too. 相似文献
6.
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
7.
通过求解具有Woods-Saxon径向标量势与矢量势的Dirac方程, 分别分析了原子核中赝自旋双重态能级劈裂和波函数下分量劈裂随着Woods-Saxon势参数的变化关系, 其中Wood-Saxon势中的参数a以及R对于赝自旋能级劈裂和波函数劈裂的影响最大, 而势阱深度V0只产生微小的影响. 随着平均场的变化, 赝自旋双重态会出现能级反转现象. 具有较大n或l的赝自旋双重态能级劈裂对于参数的变化更敏感. 赝自旋波函数下分量劈裂随着参数a和R的增大向核表面扩散, 并且在核表面附近达到最大. 赝自旋波函数劈裂随着参数a的增大而增大, 但是随着参数R或V0的增大它却在减小的. 由于在特定的同位素链中, 参数R和V0都与核子数有关系, 而参数a又是描述核的表面性质的, 所以以这些参数为变量对于赝自旋劈裂的研究是有意义的, 研究的结果至少在定性上可以应用到大部分原子核中. 相似文献
8.
《Nuclear Physics A》1997,612(2):163-203
An operator which effects the transformation to the pseudospin representation within the oscillator shell model at arbitrary triaxial deformation is constructed as a special projection of the momentum helicity operator. Since the exact transformation of many important operators cannot be performed in a closed analytical form, a procedure of approximate transformation is developed. In the spherical and asymptotic prolate limits the transforms thus derived reduce to the known exact results. The approximate transform of a modified Nilsson Hamiltonian is found to be almost indistinguishable from the “pseudo” Hamiltonian with the strongly reduced spin-orbit strength. 相似文献
9.
Pseudospin symmetric solutions of the Dirac equation with the modified Rosen—Morse potential using Nikiforov—Uvarov method and supersymmetric quantum mechanics approach 下载免费PDF全文
Wen-Li Chen 《中国物理 B》2022,31(5):50302-050302
Employing the Pekeris-type approximation to deal with the pseudo-centrifugal term, we analytically study the pseudospin symmetry of a Dirac nucleon subjected to equal scalar and vector modified Rosen-Morse potential including the spin-orbit coupling term by using the Nikiforov-Uvarov method and supersymmetric quantum mechanics approach. The complex eigenvalue equation and the total normalized wave functions expressed in terms of Jacobi polynomial with arbitrary spin-orbit coupling quantum number k are presented under the condition of pseudospin symmetry. The eigenvalue equations for both methods reproduce the same result to affirm the mathematical accuracy of analytical calculations. The numerical solutions obtained for different adjustable parameters produce degeneracies for some quantum number. 相似文献
10.
In the framework of the relativistic mean-field approach, a pseudospin dependence of the residual forces in nuclei is considered.
It is shown that this dependence is relatively weak. As a consequence, a pseudospin dependence of the particle-core coupling
is weak as well. This leads to a small splitting of the pseudospin doublets produced by a vector coupling of an odd particle
pseudospin and a pseudoorbital momentum of the core. Some possibilities for experimental investigation of the manifestations
of the pseudospin symmetry in the spectra of odd nuclei with Z ≥ 100 are indicated.
The text was submitted by the authors in English. 相似文献
11.
Using the Nikiforov-Uvarov (NU) method, pseudospin and spin symmetric solutions of the Dirac equation for the scalar and vector Hulthén potentials with the Yukawa-type tensor potential are obtained for an arbitrary spin-orbit coupling quantum number κ. We deduce the energy eigenvalue equations and corresponding upper- and lower-spinor wave functions in both the pseudospin and spin symmetry cases. Numerical results of the energy eigenvalue equations and the upper- and lower-spinor wave functions are presented to show the effects of the external potential and particle mass parameters as well as pseudospin and spin symmetric constants on the bound-state energies and wave functions in the absence and presence of the tensor interaction. 相似文献
12.
In lateral quantum dots, the combined effect of both Dresselhaus and Bychkov-Rashba spin-orbit coupling is equivalent to an effective magnetic field +/- B(SO) which has the opposite sign for s(z)= +/- 1/2 spin electrons. When the external magnetic field is perpendicular to the planar structure, the field B(SO) generates an additional splitting for electron states as compared to the spin splitting in the in-plane field orientation. The anisotropy of spin splitting has been measured and then analyzed in terms of spin-orbit coupling in several AlGaAs/GaAs quantum dots by means of resonant tunneling spectroscopy. From the measured values and sign of the anisotropy we are able to determine the dominating spin-orbit coupling mechanism. 相似文献
13.
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
14.
Yin-Wen Sun Ye Liu Shou-Wan Chen Quan Liu Jian-You Guo 《The European Physical Journal A - Hadrons and Nuclei》2012,48(2):18
Influences from different fields of mesons on the pseudospin symmetry are investigated for deformed nuclei. The energy splitting
between pseudospin partners are extracted from the relativistic mean field calculations. The results show that the σ-field contribution to the pseudospin energy splitting has nearly the same magnitude as the one obtained by the ω-field, but with opposite signs. The pseudospin energy splittings either for neutron or for protons are almost the same if
the σ-field (V
σ
) and the ω-field (V
ω
) change at the same scale. The pseudospin energy splitting depends in the same way as the nucleus binding energy of the cancellation
of these two potentials, and is controlled by the same nuclear physics scale as the potential sum V
ω
+ V
σ
In comparison with the σ- and ω-fields, it is seen that the ρ meson field produces a minor influence on the pseudospin symmetry. 相似文献
15.
The measured parameters of spin-orbit spectral splitting in HgCdTe-based MIS structures with positive and negative Kane gap E g are compared with the parameters calculated using the three-and four-band Kane model. The disregard of the finite spin-orbit splitting Δ of the valence band in calculations leads to exaggerated values of Rashba splitting (especially for E g < 0) even for small ratios |E g|/Δ, although the subband parameters averaged over two spin branches of the spectrum in the two-, three-, and four-band Kane approximations for the same concentrations are practically identical. In the zero-gap HgCdTe, the measured as well as calculated values are noticeably higher, but the four-band approximation leads to values of splitting for both materials which are 20–40% lower than the experimental value. The inclusion of the interband interaction reduces these discrepancies, but does not eliminate them completely. It is shown that the approximations of the 2D spectrum with spin-orbit splitting linear in quasimomentum, which are conventionally used in the analysis, may lower the effective Rashba parameter by a factor of 2–4. 相似文献
16.
Isospin asymmetry in the pseudospin dynamical symmetry 总被引:1,自引:0,他引:1
Alberto P Fiolhais M Malheiro M Delfino A Chiapparini M 《Physical review letters》2001,86(22):5015-5018
Pseudospin symmetry in nuclei is investigated considering the Dirac equation with a Lorentz structured Woods-Saxon potential. The isospin correlation of the energy splittings of pseudospin partners with the nuclear potential parameters is studied. We show that, in an isotopic chain, the pseudospin symmetry is better realized for neutrons than for protons. This behavior comes from balance effects among the central nuclear potential parameters. In general, we found an isospin asymmetry of the nuclear pseudospin interaction, opposed to the nuclear spin-orbit interaction which is quasi-isospin symmetric. 相似文献
17.
In this Letter, the Dirac equation is exactly solved for spatially-dependent mass Coulomb potential including a Coulomb-like tensor potential under pseudospin symmetry limit by using asymptotic iteration method with arbitrary spin-orbit coupling number κ. The energy eigenvalues and corresponding eigenfunctions are obtained and some numerical results are given. 相似文献
18.
Pseudospin and spin symmetry in the Dirac equation with Woods-Saxon potential and tensor potential 总被引:1,自引:0,他引:1
The Dirac equation is solved approximately for the Woods-Saxon potential and a tensor potential with the arbitrary spin-orbit
coupling quantum number k \kappa under pseudospin and spin symmetry. The energy eigenvalues and the Dirac spinors are obtained in terms of hypergeometric
functions. The energy eigenvalues are calculated numerically. 相似文献
19.
韩星明 《原子与分子物理学报》2009,26(5):978-984
近似研究了具有任意自旋轨道耦合项的Manning-Rosen势的Dirac方程。在赝自旋对称的条件下获得了关联的二分量的旋量及相应的能量方程。最后,对 和Hulthén 势两类特殊情况进行了简单
讨论。 相似文献