Pseudospin, supersymmetry and the shell structure of atomic nuclei
نویسنده
چکیده
The evolution of single-particle energies with varying isospin asymmetry in the shell model is an important issue when predicting changes in the shell structure for exotic nuclei. In many cases pseudospin partner levels, that are almost degenerate in energy for stable nuclei, are relevant in extracting the size of the shell gaps. A breaking of the pseudospin symmetry can affect the size of these gaps and change the magic numbers accordingly. The strength of the pseudospin splitting is expected to depend in particular on isovector-dependent and tensor contributions to the effective nuclear interaction. A description employing supersymmetric quantum mechanics allows to derive a pseudospin symmetry breaking potential that is regular in contrast to the pseudospin-orbit potential in the conventional relativistic treatment. The derived perturbation potential provides a measure to quantify the symmetry breaking and it can be employed to improve mean-field calculations in order to better reproduce the experimentally observed shell evolution. General potentials with exact pseudospin symmetry are obtained that can be used in relativistic mean-field Hamiltonians.
منابع مشابه
Pseudospin Symmetry as a Bridge between Hadrons and Nuclei
Atomic nuclei exhibit approximate pseudospin symmetry. We review the arguments that this symmetry is a relativistic symmetry. The condition for this symmetry is that the sum of the vector and scalar potentials in the Dirac Hamiltonian is a constant. We give the generators of pseudospin symmetry. We review some of the predictions that follow from the insight that pseudospin symmetry has relativi...
متن کاملNew 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 a...
متن کاملRelativistic Pseudospin Symmetry as a Supersymmetric Pattern in Nuclei
The doublet structure (for n ≥ 1) is expressed in terms of a “pseudo” orbital angular momentum l̃ = l + 1 and “pseudo” spin, s̃ = 1/2, coupled to j = l̃ − 1/2 and j = l̃ + 1/2. For example, [ns1/2, (n − 1) d3/2] will have l̃ = 1, etc. The states in Eq. (1) involve only normal-parity shellmodel orbitals. The states (n = 0, l, j = l + 1/2), with aligned spin and no nodes, are not part of a doublet. Th...
متن کاملPseudospin, Spin, and Coulomb Dirac-symmetries: Doublet Structure and Supersymmetric Patterns
The Dirac equation serves as the basis for the relativistic description of atoms, nuclei and hadrons. In atoms the relevant potentials felt by the electron are Coulombic vector potentials. A Dirac Hamiltonian with a Coulomb potential exhibits a finestructure spectrum with characteristic two-fold degeneracy. Relativistic mean fields in nuclei generated by meson exchanges , and quark confinement ...
متن کاملModeling of the hydration shell of Adenine
The molecular geometry of complex of adenine with 8 water molecules was calculated with Hartree-Fock (HF). The standard 6-31G(d) basis set has been employed. The existence of C-H…O Hydrogen bonds between the water molecules and the hydrophobic part of nucleobase is stablished. We optimized structures and computed interaction energies of all complexes of adenine with water molecules step by step...
متن کامل