BCS-BEC Crossover in Neutron Matter with RMF Effective Pairing Interaction

SUN Baoyuan; GUO Anliang; QIAN Zhuang

doi:10.11804/NuclPhysRev.35.04.505

Based on the relativistic Hartree-Bogoliubov theory in nuclear matter, the dineutron correlations and the crossover from Bardeen-Cooper-Schrieffer (BCS) region of neutron Cooper pairs to Bose-Einstein condensation (BEC) are investigated with the one-boson-exchange type of pairing force generated from the relativistic mean field (RMF) model. By introducing an effective factor χ in the RMF effective pairing interaction, the density dependence of the ratios between neutron pairing gap at Fermi surface and neutron Fermi kinetic energy △_Fn/e_Fn and the dimensionless parameter 1/(k_Fna) are analyzed quantitatively. Then the criteria where dineutron correlations exactly reach the threshold of BCS-BEC crossover or unitary limit are determined to be χ=0.51 or 0.67, respectively. In addition, features of neutron pairing gap, Cooper pair wave function and dineutron coherence length are illustrated, and the value of the probability for partner neutrons correlated within the average inter-neutron distance, namely P (d_n) ≃0.80, is obtained as a criterion of BCS-BEC crossover.

BCS-BEC Crossover in Neutron Matter with RMF Effective Pairing Interaction

1. School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;

2. Engineering Research Center for Neutron Application Technology, Ministry of Education, Lanzhou University, Lanzhou 730000, China

Funds: National Natural Science Foundation of China(11875152)

Received Date: 2018-09-29

Rev Recd Date: 2018-11-20

Publish Date: 2020-05-03

Key words:

Abstract: Based on the relativistic Hartree-Bogoliubov theory in nuclear matter, the dineutron correlations and the crossover from Bardeen-Cooper-Schrieffer (BCS) region of neutron Cooper pairs to Bose-Einstein condensation (BEC) are investigated with the one-boson-exchange type of pairing force generated from the relativistic mean field (RMF) model. By introducing an effective factor χ in the RMF effective pairing interaction, the density dependence of the ratios between neutron pairing gap at Fermi surface and neutron Fermi kinetic energy △_Fn/e_Fn and the dimensionless parameter 1/(k_Fna) are analyzed quantitatively. Then the criteria where dineutron correlations exactly reach the threshold of BCS-BEC crossover or unitary limit are determined to be χ=0.51 or 0.67, respectively. In addition, features of neutron pairing gap, Cooper pair wave function and dineutron coherence length are illustrated, and the value of the probability for partner neutrons correlated within the average inter-neutron distance, namely P (d_n) ≃0.80, is obtained as a criterion of BCS-BEC crossover.

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Reference (18)

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BCS-BEC Crossover in Neutron Matter with RMF Effective Pairing Interaction

doi: 10.11804/NuclPhysRev.35.04.505

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