Medium polarization effects in 3SD1 spin-triplet pairing

TL;DR

This paper investigates medium polarization effects on 3SD1 neutron-proton pairing in nuclear matter, revealing that self-energy corrections limit superfluidity to low densities and significantly reduce the energy gap, with implications for nuclear pairing phenomena.

Contribution

It introduces a comprehensive analysis of medium polarization effects, including vertex corrections and tensor correlations, on spin-triplet pairing within the BCS framework for nuclear matter.

Findings

Self-energy corrections confine superfluidity to very low densities.

Energy gap magnitude is significantly quenched by medium effects.

Induced interactions have an attractive influence on pairing.

Abstract

Stimulated by the still puzzling competition between spin-singlet and spin-triplet pairing in nuclei, the 3SD1 neutron-proton pairing is investigated in the framework of BCS theory of nuclear matter. The medium polarization effects are included in the single particle spectrum and also in the pairing interaction starting from the G-matrix, calculated in the Brueckner-Hartree-Fock approximation. The vertex corrections due to spin and isospin collective excitations of the medium are determined from the Bethe-Salpeter equation in the RPA limit, taking into account the tensor correlations. It is found that the self-energy corrections confine the superfluid state to very low-density, while remarkably quenching the magnitude of the energy gap, while the induced interaction has an attractive effect. The interplay between spin-singlet and spin-triplet pairing is discussed in nuclear matter as well as in finite nuclei.