We present a detailed study of partial-wave contributions of nuclear forces to pairing in nuclei. For $T=1,J=0$ pairing, partial waves beyond the standard ${}^1{\mathcal{S}}_0$ channel play an interesting role for the pair formation in nuclei. The additional contributions are dominated by the repulsive ${}^3{\mathcal{P}}_1$ partial wave. Their effects, and generally spin-triplet nuclear forces between paired nucleons, are influenced by the interplay of spin-orbit partners. We explore the impact of including partial waves beyond the ${}^1{\mathcal{S}}_0$ channel on neutron-neutron pairing gaps in semimagic isotopic chains. In addition, we show that nuclear forces favor $T=1,J=0$ over $T=0,J=1$ pairing, except in low-$j$ orbitals. This is in contrast to the free-space motivation that suggests the formation of deuteron-like $T=0$ pairs in $N=Z$ nuclei. The suppression of $T=0$ pairing is because the ${}^3{\mathcal{S}}_1$ strength is distributed on spin-orbit partners and because of the effects of the repulsive ${}^1{\mathcal{P}}_1$ channel and of $D$ waves.

• Received 19 December 2009

DOI:https://doi.org/10.1103/PhysRevC.81.064308