Pairing in neutron matter: New uncertainty estimates and three-body forces

Abstract

We present solutions of the BCS gap equation in the channels ${}^1{S}_0$ and ${}^3{P}_2-{}^3{F}_2$ in neutron matter based on nuclear interactions derived within chiral effective field theory (EFT). Our studies are based on a representative set of nonlocal nucleon-nucleon (NN) plus three-nucleon (3N) interactions up to next-to-next-to-next-to-leading order (N${}^3$LO) as well as local and semilocal chiral NN interactions up to N${}^2$LO and N${}^4$LO, respectively. In particular, we investigate for the first time the impact of subleading 3N forces at N${}^3$LO on pairing gaps and also derive uncertainty estimates by taking into account results for pairing gaps at different orders in the chiral expansion. Finally, we discuss different methods for obtaining self-consistent solutions of the gap equation. Besides the widely-used quasi-linear method by Khodel et al. we demonstrate that the modified Broyden method is well applicable and exhibits a robust convergence behavior. In contrast to Khodel's method it is based on a direct iteration of the gap equation without imposing an auxiliary potential and is straightforward to implement.

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• Broyden's Method in Nuclear Structure Calculations
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• Nuclear pairing from microscopic forces: singlet channels and higher-partial waves
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• Equation of state of superfluid neutron matter with low-momentum interactions
• Neutron star cooling and mass distributions
• The nucleardatapy toolkit for simple access to experimental nuclear data, astrophysical observations, and theoretical predictions
• Pairing properties of semilocal coordinate&momentum-space regularized chiral interactions
• The Kohn-Luttinger Effect in Dense Matter and its Implications for Neutron Stars
• Isospin-Asymmetry Dependence of the Thermodynamic Nuclear Equation of State in Many-Body Perturbation Theory
• Cold atoms beyond atomic physics
• Surface energy of magnetized superconducting matter in the neutron star cores