Influence of isoscalar and isovector pairing on Gamow-Teller transitions for nuclei in the 2p1f shell: A schematic shell model study

TL;DR

This study uses schematic shell model Hamiltonians to analyze how isoscalar and isovector pairing interactions influence Gamow-Teller transitions and nuclear properties in the 2p1f shell, comparing results with experimental data.

Contribution

It systematically investigates the impact of different pairing modes on GT transitions and nuclear spectra using schematic Hamiltonians, highlighting the role of pairing interactions in nuclear structure.

Findings

Isoscalar pairing affects ground state spins in N=Z nuclei.

Varying pairing strengths systematically alters GT transition strengths.

Model results align with experimental data when pairing interactions are properly tuned.

Abstract

We perform a systematic study of Gamow-Teller (GT) transitions in the 2p1f shell, using the nuclear shell model with two schematic Hamiltonians. The use of the shell model provides flexibility to analyze the role of different proton-neutron pairing modes in the presence of nuclear deformation. The schematic Hamiltonians that are used contain a quadrupole-quadrupole interaction as well as isoscalar (T=0) and isovector (T=1) pairing interactions, but differ in the single particle energies. The objective of the work is to observe the behavior of GT transitions in different isoscalar and isovector pairing scenarios, together with the corresponding energy spectra and rotational properties of the parent and daughter nuclei (42Ca -> 42Sc, 44Ca -> 44Sc, 46Ti -> 46V, 48Ti -> 48V). We also treat the rotational properties of 44Ti and 48Cr. All results are compared with experimental data. The results obtained from our models depend on the different scenarios that arise, whether for N = Z or N neq Z nuclei. In the latter case, the presence of an attractive isoscalar pairing interaction imposes a 1+ ground state in odd-odd nuclei, contrary to observations for some of the nuclei considered, and it is necessary to suppress that pairing mode when considering such nuclei. The effect of varying the strength parameters for the two pairing modes is found to exhibit different but systematic effects on energy spectra and on GT transition properties.