Eur. Phys. J. A (2008) 37: 251
https://doi.org/10.1140/epja/i2008-10619-1

Regular Article - Theoretical Physics

Pseudospin symmetry as an accidental symmetry in the relativistic framework

¹ Departamento de Física Moderna, Universidad de Cantabria, E-39005, Santander, Spain
² Departamento de Física Aplicada, Universidad de Cantabria, E-39005, Santander, Spain
³ Department of Physics, St. Petersburg University for Telecommunications, 191065, St. Petersburg, Russia

^a marcoss@unican.es

Received: 26 April 2008
Revised: 17 June 2008
Published online: 17 July 2008

Abstract

We analyse the arguments used in the relativistic context to base the quasi-degeneracy of pseudospin doublets (PSDs) observed in atomic nuclei on the smallness of the single-particle central potential (Σ_S + Σ₀), discussing, especially, the implications of the results obtained in the limit (Σ_S + Σ₀ = 0. We study also the transition from a relativistic model, where Σ_S + Σ₀ is a harmonic-oscillator potential and exhibits degenerate PSDs, to a more realistic one with broken pseudospin symmetry. We examine, in particular, the effect of the corresponding pseudospin symmetry-breaking term on the Dirac spinors of the PSDs. An extension of the Nilsson model to the relativistic case is also considered.