Eur. Phys. J. A (2006) 27: 277-282
https://doi.org/10.1140/epja/i2006-08-042-5

Nuclear Physics in Astrophysics II

A simple interpretation of global trends in the lowest levels of p- and sd-shell nuclei

¹ Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4001, Debrecen, Hungary
² Instituto de Ciencias Nucleares, 04510, México D.F., Mexico

Received: 2 July 2005
Accepted: 20 December 2005
Published online: 23 March 2006

Abstract

A simple approach is presented to estimate the position of the first opposite-parity state for p- and sd-shell nuclei. The approach is based on the assumption that the quadrupole-quadrupole interaction determines the energy of the lowest-lying states, and they are a mixture of a few leading SU(3) irreps even in the presence of further symmetry-breaking interactions. The quadrupole-quadrupole interaction together with the indirect effect of the Pauli exclusion principle will then lead to a rich structure in the trends of observables along Z, N and A chains. A comparison with the experimental data is given, with the carbon chain as illustrative example. The findings suggest that the changing shell structure near the neutron drip line might be explained by the appearance of low-lying highly deformed 2ℏω states.