Neutron-Proton Pairing and its Impact on Gamow-Teller Transitions

Abstract

We report a systematic study of Gamow-Teller (GT) transitions in the 2p1f shell, using the nuclear shell model with a schematic Hamiltonian. The Hamiltonian used contains a quadrupole-quadrupole interaction, isoscalar (T = 0) and isovector (T = 1) pairing interactions as well as a single-particle energy term. The objective of the work is to observe the behavior of GT transitions in different isoscalar and isovector pairing scenarios. We also study their corresponding effect on the energy spectra of the parent and daughter nuclei involved in the GT decays. All results are discussed in relation to experimental data. A key conclusion reached is that with the schematic Hamiltonian we use it is essential to suppress the isoscalar pairing mode when treating nuclei with a neutron excess to avoid producing spurious results for the ground state spin and parity. Varying the strength parameters for the two pairing modes is found to exhibit different but systematic effects on GT transition properties and on the corresponding energy spectra.