Pairing in bulk nuclear matter beyond BCS

TL;DR

This paper investigates how short- and long-range correlations affect neutron pairing in bulk nuclear matter, finding that these correlations suppress the superfluid gap across various realistic interactions.

Contribution

It introduces a comprehensive approach incorporating short- and long-range correlations into the neutron pairing gap calculation beyond BCS theory.

Findings

Short-range correlations eliminate the pairing gap in the ${}^3P_2-{}^3F_2$ channel.

Long-range polarization effects do not restore the gap with reasonable Landau parameters.

The pairing interaction becomes slightly more attractive but remains insufficient to produce a gap.

Abstract

The influence of short-range correlations on the spectral distribution of neutrons is incorporated in the solution of the gap equation for the ${}^3P_2-{}^3F_2$ coupled channel in pure neutron matter. This effect is studied for different realistic interactions including one based on chiral perturbation theory. The gap in this channel vanishes at all relevant densities due to the treatment of these correlations. We also consider the effect of long-range correlations by including polarization terms in addition to the bare interaction which allow the neutrons to exchange density and spin fluctuations governed by the strength of Landau parameters allowed to have reasonable values consistent with the available literature. Preliminary results indicate that reasonable values of these parameters do not generate a gap in the ${}^3P_2-{}^3F_2$ coupled channel either for all three realistic interactions although the pairing interaction becomes slightly more attractive.