Generalized seniority with realistic interactions in open-shell nuclei

Abstract

Generalized seniority provides a truncation scheme for the nuclear shell model, based on pairing correlations, which offers the possibility of dramatically reducing the dimensionality of the nuclear shell-model problem.Systematic comparisons against results obtained in the full shell-model space are required to assess the viability of this scheme. Here, we extend recent generalized seniority calculations for semimagic nuclei, the Ca isotopes, to open-shell nuclei, with both valence protons and valence neutrons. The even-mass Ti and Cr isotopes are treated in a full major shell and with realistic interactions, in the generalized seniority scheme with one broken proton pair and one broken neutron pair. Results for level energies, orbital occupations, and electromagnetic observables are compared with those obtained in the full shellmodel space. We demonstrate that, even for the Ti isotopes, significant benefit would be obtained in going beyond the approximation of one broken pair of each type, while the Cr isotopes require further broken pairs to provide even qualitative accuracy.

Nuclear matrix elements for double-βdecay

“…[103] for 116 Sn, while 48 Ca has been taken as doubly magic. This procedure is compatible with the generalized seniority (GS) scheme, which appears to be good for semi-magic nuclei, as extensively discussed in the 1980s for pairing plus quadrupole interactions, and as shown recently for realistic interactions [110]. …”

Collective 2+ 1 excitations in 206Po and 208,210Rn

“…However, as concluded in Ref. [8], the generalised seniority scheme with realistic interactions is inadequate to describe open-shell nuclei. In Ref.…”

Description of even-even Ti isotopes within IBM-1 model

“…During the last decades, the nuclei in A~50 mass region were investigated as reported in Refs. [3][4][5][6][7][8][9]. The shape phase transition was studied for the light nuclei with number of proton Z=20-28 including also Ti isotopes [3].…”

“…The fully-microscopic shell-model (SM) were used to calculate the first 2 + states of Ti isotopes and their B(E2) transition rates along the isotopic chain [4]. Excitation 2 + , 4 + energy states, B(E2) values, and Q(2 + ) of even-even Ca, Ti, Cr isotopes were calculated in the generalized seniority with realistic interactions and compared with results of full SM calculations performed by using FPD6 and GXPF1 interactions [5]. The shape phase transition was studied for Ti isotopes within the Hartree-Fock-Bogoliubov (HFB) approach and 46,52,60 Ti isotopes show E(5) behavior [6].…”