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Transition from BCS pairing to Bose-Einstein condensation in low-density asymmetric nuclear matter

U. Lombardo·P. Nozieres·P. Schuck·H. -J. Schulze·A. Sedrakian
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Abstract

We study the isospin-singlet neutron-proton pairing in bulk nuclear matter as a function of density and isospin asymmetry within the BCS formalism. In the high-density, weak-coupling regime the neutron-proton paired state is strongly suppressed by a minor neutron excess. As the system is diluted, the BCS state with large, overlapping Cooper pairs evolves smoothly into a Bose-Einstein condensate of tightly bound neutron-proton pairs (deuterons). In the resulting low-density system a neutron excess is ineffective in quenching the pair correlations because of the large spatial separation of the deuterons and neutrons. As a result, the Bose-Einstein condensation of deuterons is weakly affected by an additional gas of free neutrons even at very large asymmetries.

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U. Lombardo, P. Nozieres, P. Schuck, H. -J. Schulze, A. Sedrakian. 2001-09-10. Transition from BCS pairing to Bose-Einstein condensation in low-density asymmetric nuclear matter. https://doi.org/10.1103/physrevc.64.064314

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