The mean-field theory of superfluid-superconducting vortex states in the outer core of neutron stars

Fuente: arXiv
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Autore principale: Kobyakov, Dmitry
Natura: Preprint
Pubblicazione: 2026
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author Kobyakov, Dmitry
author_facet Kobyakov, Dmitry
contents Purpose: Characterize superfluid-superconducting vortex states at arbitrary pressures with $T_{cp}\neq T_{cn}$, assuming both proton and neutron mean-fields are formed by spin-0 Cooper pairs. Method: The existing mean-field theory is extended to account for $T_{cp}\neq T_{cn}$. The pressure dependence of the pairing gap energy $Δ_{\alpha0}$ is quantitatively established on the basis of the effective chiral field theory. To link $T_{cα}$ with $Δ_{\alpha0}$, I use the weak-coupling result $T_{cα}\approx0.57Δ_{\alpha0}$. A quadratic scaled-temperature ($T/T_{cp}$) dependence of the thermodynamic magnetic field is postulated in analogy with pure superconductors. The $T/T_{cα}$-dependence of the gap $Δ_{αT}$ is inferred from the many-body approximations for the pure neutron matter. Results: An empirical $T/T_{cα}$-dependence for the mean-field is constructed to account for the interplay between the condensation and the magnetic energies. The superfluid entrainment is found to increase the size of the vortex core and to decrease the effective magnetic penetration depth. The size of the neutron vortex core is found to be larger than the magnetic penetration depth in the outer core. Conclusions: The usual approximation of infinitely thin vortex line (the London's approximation) for the neutron vortex is found to be irrelevant in the entire outer core and for the proton vortex is found to be limited to vicinity of the crust-core transition. The developed mean-field theory paves the way to study the vortex microscopic structure, the angular momentum, the magnetization and the vortex-fluxtube interaction energy.
format Preprint
id arxiv_https___arxiv_org_abs_2605_11216
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The mean-field theory of superfluid-superconducting vortex states in the outer core of neutron stars
Kobyakov, Dmitry
Nuclear Theory
Solar and Stellar Astrophysics
Superconductivity
Purpose: Characterize superfluid-superconducting vortex states at arbitrary pressures with $T_{cp}\neq T_{cn}$, assuming both proton and neutron mean-fields are formed by spin-0 Cooper pairs. Method: The existing mean-field theory is extended to account for $T_{cp}\neq T_{cn}$. The pressure dependence of the pairing gap energy $Δ_{\alpha0}$ is quantitatively established on the basis of the effective chiral field theory. To link $T_{cα}$ with $Δ_{\alpha0}$, I use the weak-coupling result $T_{cα}\approx0.57Δ_{\alpha0}$. A quadratic scaled-temperature ($T/T_{cp}$) dependence of the thermodynamic magnetic field is postulated in analogy with pure superconductors. The $T/T_{cα}$-dependence of the gap $Δ_{αT}$ is inferred from the many-body approximations for the pure neutron matter. Results: An empirical $T/T_{cα}$-dependence for the mean-field is constructed to account for the interplay between the condensation and the magnetic energies. The superfluid entrainment is found to increase the size of the vortex core and to decrease the effective magnetic penetration depth. The size of the neutron vortex core is found to be larger than the magnetic penetration depth in the outer core. Conclusions: The usual approximation of infinitely thin vortex line (the London's approximation) for the neutron vortex is found to be irrelevant in the entire outer core and for the proton vortex is found to be limited to vicinity of the crust-core transition. The developed mean-field theory paves the way to study the vortex microscopic structure, the angular momentum, the magnetization and the vortex-fluxtube interaction energy.
title The mean-field theory of superfluid-superconducting vortex states in the outer core of neutron stars
topic Nuclear Theory
Solar and Stellar Astrophysics
Superconductivity
url https://arxiv.org/abs/2605.11216