Origin of Pseudospin Symmetry

Blokhin, A. L.; Bahri, C.; Draayer, J. P.

doi:10.1103/physrevlett.74.4149

Cited by 139 publications

(150 citation statements)

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“…Since the concept of pseudospin (PS) was introduced more than 40 years ago [2,3], the pseudospin symmetry (PSS) in single particle states has been an interesting topic in nuclear physics [4,5,6]. In 1997 it was found that the PSS in nuclei is a relativistic symmetry which is exactly conserved when the scalar and vector potentials have the same size but opposite sign, i.e., Σ(r) ≡ S(r) +V (r) = 0 [7].…”

Section: Introductionmentioning

confidence: 99%

Exact conservation and breaking of pseudospin symmetry in single particle resonant states

Lü¹,

Zhao²,

Zhou³

2013

AIP Conference Proceedings

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Abstract. In this contribution we present some results on the study of pseudospin symmetry (PSS) in single particle resonant states. The PSS is a relativistic dynamical symmetry connected with the small component of the nucleon Dirac wave function. Many efforts have been made to study this symmetry in bound states. We recently gave a rigorous justification of the PSS in single particle resonant states by examining the zeros of Jost functions corresponding to the small components of the radial Dirac wave functions and phase shifts of continuum states [1]. We have shown that the PSS in single particle resonant states in nuclei is conserved when the attractive scalar and repulsive vector potentials have the same magnitude but opposite sign. Examples of exact conservation and breaking of this symmetry in single particle resonances are given for spherical square-well and Woods-Saxon potentials.

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Section: Introductionmentioning

confidence: 99%

Exact conservation and breaking of pseudospin symmetry in single particle resonant states

Lü¹,

Zhao²,

Zhou³

2013

AIP Conference Proceedings

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“…Exact pseudospin symmetry means degeneracy of doublets whose angular momentum quantum numbers are j =l ±s. This symmetry in nuclei was first reported about 30 years ago [1], but only recently has its origin become a topic of intense theoretical research.In recent papers [2,3,4,5,6] possible underlying mechanisms to generate such symmetry have been discussed. We briefly review the main points of these studies.…”

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confidence: 99%

“…In recent papers [2,3,4,5,6] possible underlying mechanisms to generate such symmetry have been discussed. We briefly review the main points of these studies.…”

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confidence: 99%

Isospin Asymmetry in the Pseudospin Dynamical Symmetry

et al. 2001

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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.PACS numbers: 21.10. Hw, 21.30.Fe, 21.60.Cs In some heavy nuclei a quasi-degeneracy is observed between single-nucleon states with quantum numbers (n, ℓ, j = ℓ + 1/2) and (n − 1, ℓ + 2, j = ℓ + 3/2) where n, ℓ, and j are the radial, the orbital, and the total angular momentum quantum numbers, respectively. This doublet structure is better expressed using a "pseudo" orbital angular momentum quantum number,l = ℓ + 1, and a "pseudo" spin quantum number,s = 1/2. For example, for [ns 1/2 , (n − 1)d 3/2 ] one hasl = 1, for [np 3/2 , (n − 1)f 5/2 ] one hasl = 2, etc. Exact pseudospin symmetry means degeneracy of doublets whose angular momentum quantum numbers are j =l ±s. This symmetry in nuclei was first reported about 30 years ago [1], but only recently has its origin become a topic of intense theoretical research.In recent papers [2,3,4,5,6] possible underlying mechanisms to generate such symmetry have been discussed. We briefly review the main points of these studies.Blokhin et al.[2] performed a helicity unitary transformation in a nonrelativistic single-particle Hamiltonian. They showed that the transformed radial wave functions have a different asymptotic behavior, implying that the helicity transformed mean field acquires a more diffuse surface. Application of the helicity operator to the nonrelativistic single-particle wave function maps the normal state (l, s) onto the "pseudo" state (l,s), while keeping all other global symmetries [2]. The same kind of unitary transformation was also considered earlier by Bahri et al.[3] to discuss the pseudospin symmetry in the nonrelativistic harmonic oscillator. They showed that a particular condition between the coefficients of spin-orbit and orbit-orbit terms, required to have a pseudospin symmetry in that non-relativistic single particle Hamiltonian, was consistent with relativistic mean-field (RMF) estimates.Ginocchio [4], for the first time, identified the pseudospin symmetry as a symmetry of the Dirac Hamiltonian. He pointed out that the pseudo-orbital angular momentum is just the orbital angular momentum of the lower component of the Dirac spinor. Thus, the pseudospin symmetry started to be regarded and understood in a relativistic way. He also showed that the pseudospin symmetry would be exact if the attractive scalar, S, and the repulsive vector, V , components of a Lorentz structured potential were equal in magnitude: S + V = 0. Under this condition, the pseudospi...

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“…whereŝ µ = σ µ /2 are the usual spin generators, σ µ the Pauli matrices, and U p = σ · p p is the momentum-helicity unitary operator introduced in [9]. If in addition the potentials are spherically symmetric, the Dirac Hamiltonian has an additional invariant SU(2) algebra, [ H ,L µ ] = 0, with the relativistic pseudo-orbital angular momentum operators given by…”

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confidence: 99%