Triplet Pairing in pure neutron matter

TL;DR

This paper investigates the effects of many-body interactions and self-energy corrections on triplet pairing gaps in pure neutron matter, using SRG-evolved interactions and analyzing their impact on the BCS transition temperature and density dependence.

Contribution

It provides a detailed analysis of how three-body forces and self-energy corrections influence neutron matter pairing gaps and their scale dependence, highlighting the importance of higher-order effects.

Findings

Self-energy effects significantly reduce the pairing gap and shift gap closure to lower densities.

Self-energy corrections decrease SRG scale dependence, improving result stability.

Three-body effects at leading order do not alter two-body scale dependence but depend strongly on the three-body cut-off.

Abstract

We study the zero temperature BCS gaps for the triplet channel in pure neutron matter using Similarity Renormalization Group (SRG) evolved interactions. We use the dependence of the results on the SRG resolution scale, as a tool to analyze medium and many-body corrections. In particular, we study the effects of including the three-body interactions at leading order, which appear at N2LO in the Chiral EFT, as well as that of the first-order self-energy corrections on the zero temperature gap. In addition we also extract the transition temperature as a function of densities and verify the BCS scaling of the zero temperature gaps to the transition temperature. We observe that the self-energy effects are very crucial in order to reduce the SRG resolution scale dependence of the results, while the three-body effects at the leading order do not change the two-body resolution scale dependence. On the other hand, the results depend strongly on the three-body cut-off, emphasizing the importance of the missing higher-order three-body effects. We also observe that self-energy effects reduce the overall gap as well as shift the gap closure to lower densities.