共查询到20条相似文献,搜索用时 15 毫秒
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Influence of different fields of mesons on the pseudospin symmetry in single-neutron resonant states
In the framework of the relativistic mean field theory combined with the complex momentum representation method, we elucidate the pseudospin symmetry in the single-neutron resonant states and its dependence on the \begin{document}$\sigma$\end{document} ![]()
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, \begin{document}$\omega$\end{document} ![]()
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, and \begin{document}$\rho$\end{document} ![]()
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meson fields. Compared with the effect of the \begin{document}$\rho$\end{document} ![]()
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field, the \begin{document}$\sigma$\end{document} ![]()
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and \begin{document}$\omega$\end{document} ![]()
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fields provide the main contributions to the pseudospin energy and width splitting of the resonant pseudospin doublets. Especially, we compare quantitatively the pseudospin wave functions' splittings in resonant doublets, and investigate their dependencies on different fields of mesons, which is consistent with that of energy and width splittings. Current research is helpful to understand the mechanism and properties of pseudospin symmetry for resonant states. 相似文献
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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
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《Nuclear Physics A》1987,462(4):781-790
Various aspects of the scattering of medium energy K+ mesons on deformed nuclei are investigated in the light of a specific example, viz. the scattering of 800 MeV/c positive kaons on 152Sm. The effects of coupled channels are found to be significant despite the fact that the K+ meson is a rather weakly interacting hadronic probe. The localization of the reaction mechanism on a deformed target is discussed for both protons and K+ mesons to compare the extent of surface and volume probing capability of these two projectiles. The results show the remarkable sensitivity of the elastic and inelastic K+ differential cross sections to the differences between the neutron and proton density distributions in deformed nuclei. 相似文献
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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
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The relevance of pseudospin symmetry in nuclei is considered. New insights are obtained from looking at the continuous transition
from a non-relativistic model satisfying spin symmetry to another one satisfying pseudospin symmetry. This study suggests
that there are models allowing no missing single-particle states in this transition, contrary to what is usually advocated.
It rather points to an association of pseudospin partners that is quite different from the one generally assumed, together
with a strong violation of the corresponding symmetry. This assignment is supported by an examination of the wave functions
and related quantities for the pseudospin partners. 相似文献
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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
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Using the fact that pseudospin is an approximate symmetry of the Dirac Hamiltonian with realistic scalar and vector mean fields, we derive the wave functions of the pseudospin partners of eigenstates of a realistic Dirac Hamiltonian and compare these wave functions with the wave functions of the Dirac eigenstates. 相似文献
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M.W. Guidry R.E. Neese C.R. Bingham L.L. Riedinger J.A. Vrba I.Y. Lee N.R. Johnson G.R. Satchler P.A. Butler R. Donangelo J.O. Rasmussen D.L. Hillis H.H. Kluge 《Nuclear Physics A》1984,430(2):485-524
Theoretical and experimental methods for studying heavy-ion inelastic scattering from deformed nuclei are described. The theoretical methods involve classical-limit approximations, while particle- γ-spectroseopy techniques are employed experimentally. With these approaches, heavy-ion excitation in the Coulomb-nuclear interference region acquires a transparent interpretation, despite the apparent complexity of the multistep excitation processes involved. The examples discussed provide a good illustration of the relationship between classical and quantum physics. The sensitivity of the inelastic scattering to details of the surface ion-ion potential due to radial and angular localization is exploited to provide a method of determining the equipotential contours in a direct manner which bypasses particular model-dependent parametrizations. The method is used to construct ion-ion potentials from inelastic scattering data for the systems 40Ar + 160Gd, 156Gd, 162Dy, 164Dy, and180Hf. The contribution of adiabatic giant resonance polarization to this potential is discussed. The relation between the deformed ion-ion potential and nuclear shapes is illustrated by comparing the experimental potentials to deformed double-folding and deformed proximity-potential calculations. 相似文献
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Measurements are presented of the cross sections for omega meson photoproduction at a mean energy of 3.9 GeV from nuclear targets of D, Be, C, Al, Cu, Ag, Au. An optical and Glauber model analysis of the coherent cross sections has been performed to obtain the ω-nucleon cross section, σωN, and the photon-omega coupling constant γω2/4π. Our results are summarised in table 4. We find good agreement with the quark model prediction that σωN = σ?N, and with the value of γω2/4π determined from the storage ring experiments and from an earlier complex nuclei measurement. However, we disagree with more recent complex nuclei measurements which found a high value of γω2/4π. 相似文献
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B. Krusche 《The European physical journal. Special topics》2011,198(1):199-238
Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major
lines of research related to the properties of the strong interaction. The investigation of nucleon resonances requires light
nuclei as targets for the extraction of the isospin composition of the electromagnetic excitations. This is done with quasi-free
meson photoproduction off the bound neutron and supplemented with the measurement of coherent photoproduction reactions, serving
as spin and/or isospin filters. Furthermore, photoproduction from light and heavy nuclei is a very efficient tool for the
study of the interactions of mesons with nuclear matter and the in-medium properties of hadrons. Experiments are currently
rapidly developing due to the combination of high quality tagged (and polarized) photon beams with state-of-the-art 4π detectors
and polarized targets. 相似文献
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N. Lo Iudice 《Czechoslovak Journal of Physics》1998,48(6-7):741-744
Collective and microscopic properties of the low-lying, scissors-like, M1 excitations are studied. The collective features
are analyzed in RPA using an energy-weighted M1 sum rule.
Presented at the International Conference on “Atomic Nuclei and Metallic Clusters”, Prague, September 1–5, 1997. 相似文献
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Shape observables measuring the intrinsic quadrupole deformation of the nucleus are identified. The consequences of these shape operators for the collective rotational and SU(3) models are derived. The operator measuring the square of the K quantum number is given. 相似文献
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R. F. Wagenbrunn 《Few-Body Systems》2008,43(1-4):241-246
Results on the spectrum of ${\bar q} q$ mesons in a model with a linear Coulomb-like instantaneous confining potential are presented. The single-quark Green function as well as the dynamical chiral symmetry breaking are obtained from the Dyson-Schwinger (gap) equation. Given the dressed quark propagator, the spectrum of “usual” mesons, i.e., ${\bar q} q$ states with nonexotic quantum numbers J PC , is obtained from the Bethe-Salpeter equation. Effective restoration of chiral symmetry at large spins and/or radial excitations is observed and the states fall into approximate linear radial and angular Regge trajectories. 相似文献
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在赝自旋对称性条件下,严格求解了四参量双原子分子势中运动粒子的s波Klein-Gordon方程和Dirac方程,并给出了相应的束缚态能谱和相对论性波函数. 相似文献
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Chiral symmetry in nuclei 总被引:1,自引:0,他引:1
Effective field theory is considered to provide a highly useful framework for connecting nuclear physics with the symmetries and dynamics of the underlying theory of strong interactions, QCD. Of many issues that are of great current interest in this domain, I concentrate here on two: (1) A new class of ab initio calculations of observables in two-nucleon systems; (2) Attempts to extend chiral perturbation calculations to higher-order terms. 相似文献