Dineutron correlations in quasi two-dimensional systems in a simplified model and possible relation to neutron-rich nuclei

Abstract

Two-neutron correlation in the ${}^{1}S$ channel in quasi two-dimensional (2D) neutron systems at zero temperature is studied by means of the BCS theory with finite-range effective nuclear forces. The dineutron correlation in low density neutron systems confined in an infinite slab is investigated in a simplified model that neutron motion of one direction is frozen. When the slab is thin enough, two neutrons form a tightly bound dineutron with a small size in the quasi-2D system, and a Bose dineutron gas is found in low density limit. With increase of Fermi momentum, the neutron system changes from the Bose-gas phase to the superfluid Cooper pair phase. The density dependence of the neutron pairing shows the BCS-BEC crossover phenomena at finite low-density region. In the transition region, the size shrinking of neutron pair and enhancement of pairing gap are found. The relation to dineutron correlation at surface of neutron-rich nuclei is also discussed.

18 pages, 10 figures

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• Diproton correlation in a proton-rich Borromean nucleus 17Ne
• BCS-BEC crossovers and unconventional phases in dilute nuclear matter
• Two-particle spatial correlations in superfluid nuclei
• Phase diagram of dilute nuclear matter: Unconventional pairing and the BCS-BEC crossover
• BCS-BEC crossover in nuclear matter with the relativistic Hartree-Bogoliubov theory
• Cooper pair sizes in 11Li and in superfluid nuclei: a puzzle?
• Effect of proton-proton Coulomb repulsion on soft dipole excitations of light proton-rich nuclei
• Dineutron correlations and BCS-BEC crossover in nuclear matter with the Gogny pairing force
• Drastic change in inelastic scattering depending on the development of dineutron correlation in ${}^{10}$Be
• Brueckner $G$-matrix approach to two-dimensional Fermi gases with the finite-range attractive interaction
• Nuclear systems under extreme conditions: isospin asymmetry and strong B-fields