Role of the Coulomb and the vector-isovector ρ\rho potentials in the isospin asymmetry of nuclear pseudospin

We investigate the role of the Coulomb and the vector-isovector $\rho$ potentials in the asymmetry of the neutron and proton pseudospin splittings in nuclei. To this end, we solve the Dirac equation for the nucleons using central vector and scalar potentials with Woods-Saxon shape and $Z$ and $N-Z$ dependent Coulomb and $\rho$ potentials added to the vector potential. We study the effect of these potentials on the energy splittings of proton and neutron pseudospin partners along a Sn isotopic chain. We use an energy decomposition proposed in a previous work to assess the effect of a pseudospin-orbit potential on those splittings. We conclude that the effect of the Coulomb potential is quite small and the $\rho$ potential gives the main contribution to the observed isospin asymmetry of the pseudospin splittings. This isospin asymmetry results from a cancellation of the various energy terms and cannot be attributed only to the pseudospin-orbit term, confirming the dynamical character of this symmetry pointed out in previous works.Comment: 9 pages, 11 figures, uses revtex4; title was changed and several small corrections were made throughout the tex

Pseudospin symmetry as a relativistic dynamical symmetry in the nucleus

Pseudospin symmetry in nuclei is investigated by solving the Dirac equation with Woods-Saxon scalar and vector radial potentials, and studying the correlation of the energy splittings of pseudospin partners with the nuclear potential parameters. The pseudospin interaction is related to a pseudospin-orbit term that arises in a Schroedinger-like equation for the lower component of the Dirac spinor. We show that the contribution from this term to the energy splittings of pseudospin partners is large. The near pseudospin degeneracy results from a significant cancelation among the different terms in that equation, manifesting the dynamical character of this symmetry in the nucleus. We analyze the isospin dependence of the pseudospin symmetry and find that its dynamical character is behind the different pseudospin splittings observed in neutron and proton spectra of nuclei.Comment: 13 pages, 9 figures, uses REVTeX4 macro

New insight on pseudospin doublets in nuclei

The relevance of the pseudospin symmetry in nuclei is considered. New insight is obtained from looking at the continuous transition from a model satisfying the spin symmetry to another one satisfying the 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 out to an association of pseudospin partners different from the one usually assumed, together with a strong violation of the corresponding symmetry. A comparison with results obtained from some relativistic approaches is made.Comment: 27 pages, 18 figure

Spin-orbit splittings in heavy-light mesons and Dirac equation

The spin-orbit splitting in heavy-light mesons is seen to be suppressed experimentally. It is shown that it can be understood qualitatively in the frame work of Dirac theory. An alternative derivation of a relativistic dynamical symmetry for the Dirac Hamiltonian, which suppresses spin orbit splitting, is also given. However it is shown that such a symmetry is not needed since the spin-orbit splitting in Dirac theory with Coulomb like potential (as is the case for the one gluon exchange potential in pQCD) is small anyway.Comment: 9 pages, 1 fi

Modern education trends and value meanings of teacher education

This article presents analytical data on emerging or educational trends and an attempt to determine the value meanings of teacher education. Revealing the content of the article, the authors determine the main educational trends that affect the content of a modern teacher professional activities, which are classified by the authors into groups. The value meaning of modern pedagogical education is substantiated - the formation of a future bioethical culture among future teachers and their preparation for the translation of this culture into society and into the educational system.Este artículo presenta datos analíticos sobre tendencias emergentes o educativas y un intento de determinar los significados de valor de la formación docente. Al revelar el contenido del artículo, los autores determinan las principales tendencias educativas que afectan el contenido de las actividades profesionales de un maestro moderno, que los autores clasifican en grupos. El significado del valor de la educación pedagógica moderna está justificado: la formación de una futura cultura bioética entre los futuros docentes y su preparación para la traducción de esta cultura a la sociedad y al sistema educativo