Variational and parquet-diagram calculations for neutron matter. III. S-wave pairing

TL;DR

This paper uses advanced diagrammatic methods to calculate the superfluid gap in neutron matter, highlighting the importance of non-parquet diagrams and corrections for accurate results consistent with Quantum Monte Carlo data.

Contribution

It introduces the inclusion of non-parquet diagram contributions and superfluid-specific propagators into neutron matter pairing calculations, improving accuracy over previous methods.

Findings

Diagrammatic contributions outside the parquet class are significant.

Superfluid-specific propagators suppress spin-channel contributions.

Results align well with Quantum Monte Carlo data.

Abstract

We apply parquet-diagram summation methods for the calculation of the superfluid gap in $S$-wave pairing in neutron matter for realistic nucleon-nucleon interactions such as the Argonne $v_6$ and the Reid $v_6$ potentials. It is shown that diagrammatic contributions that are outside the parquet class play an important role. These are, in variational theories, identified as so-called "commutator contributions". Moreover, using a particle-hole propagator appropriate for a superfluid system results in the suppression of the spin-channel contribution to the induced interaction. Applying these corrections to the pairing interaction, our results agree quite well with Quantum Monte Carlo data.