Superfluid neutron matter with a twist

Abstract

Superfluid neutron matter is a key ingredient in the composition of neutron stars. The physics of the inner crust is largely dependent on that of its $S$-wave neutron superfluid which has made its presence known through pulsar glitches and modifications on the neutron star cooling. Moreover, with recent gravitational-wave observations of neutron star mergers, the need for an equation of state for the matter of these compact stars is further accentuated and a model-independent treatment of neutron superfluidity is important. \textit{Ab initio} techniques developed for finite systems can be guided to perform extrapolations to the thermodynamic limit and attain this model-independent extraction of various quantities of infinite superfluid neutron matter. To inform such an extrapolation scheme, we performed calculations of the neutron ${}^1{S}_0$ pairing gap using the model-independent odd-even staggering in the context of the particle-conserving, projected BCS theory under twisted boundary conditions. While the practice of twisted boundary conditions is standard in solid state physics and has been used repeatedly in the past to reduce finite-size effects, this is the first time it is employed in the context of pairing. We find that a twist-averaging approach results in a substantial reduction of the finite-size effects, bringing systems with $N⪆50$ within a $2\%$ error margin from the infinite system. This can significantly reduce extrapolation-related errors in the extraction of superfluid neutron matter quantities.

22 pages, 10 figures; v2 corresponds to published version

References in corpus (23)

• Theory of ultracold Fermi gases
• Color superconductivity in dense quark matter
• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
• Molecular Probe of Pairing in the BEC-BCS Crossover
• Models of Pulsar Glitches
• Local chiral effective field theory interactions and quantum Monte Carlo applications
• Strongly paired fermions: Cold atoms and neutron matter
• Screening Effects in Superfluid Nuclear and Neutron Matter within Brueckner Theory
• Equation of state of superfluid neutron matter and the calculation of ${}^1{S}_0$ pairing gap
• Low-energy collective excitations in the neutron star inner crust
• Neutron drip transition in accreting and nonaccreting neutron star crusts
• Entrainment in Superfluid Neutron Star Crusts: Hydrodynamic Description and Microscopic Origin
• Nuclear pairing from microscopic forces: singlet channels and higher-partial waves
• Role of the symmetry energy and the neutron-matter stiffness on the tidal deformability of a neutron star with unified equations of state
• Unified description of neutron superfluidity in the neutron-star crust with analogy to anisotropic multi-band BCS superconductors
• Dependence of the BCS 1S0 superfluid pairing gap on nuclear interactions
• A superfluid perspective on neutron star dynamics
• Collective Modes in a Superfluid Neutron Gas within the Quasiparticle Random-Phase Approximation
• Nucleus--nucleus interactions in the inner crust of neutron stars
• Comparison between the Thomas-Fermi and Hartree-Fock-Bogoliubov Methods in the Inner Crust of a Neutron Star: The Role of Pairing Correlations
• Anderson-Bogoliubov phonon in inner crust of neutron stars: Dipole excitation in spherical Wigner-Seitz cell
• BCS-BEC Crossover Effects and Pseudogap in Neutron Matter