Effect of isoscalar spin-triplet pairings on spin-isospin responses in $sd-$ shell nuclei

Abstract

The spin magnetic dipole transitions and the neutron-proton spin-spin correlations in $sd-$shell even-even nuclei with $N=Z$ are investigated using shell model wave functions. The isoscalar spin-triplet pairing correlation provides a substantial quenching effect on the spin magnetic dipole transitions, especially the isovector (IV) ones. Consequently, an enhanced isoscalar spin-triplet pairing interaction influences the proton-neutron spin-spin correlation deduced from the difference between the isoscalar (IS) and the IV sum rule strengths. The effect of the $\Delta$ (${\Delta }_{33}$ resonance)-hole coupling is examined in the IV spin transition and the spin-spin correlations of the ground states.