Density, spin and isospin correlations in low-density two-component Fermi superfluid

• Published in: Физика низких температур
• Date: 2006
• Main Authors: Isayev, A.A., Yang, J.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2006
• Subjects: Квантовые жидкости и квантовые кpисталлы
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/120616
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Density, spin and isospin correlations in low-density
 two-component Fermi superfluid / A.A. Isayev, J. Yang // Физика низких температур. — 2006. — Т. 32, № 10. — С. 1195–1202. — Бібліогр.: 22 назв. — англ.

Finding the distinct features of the crossover from the regime of large overlapping Cooper pairs
 to the limit of non-overlapping pairs of fermions (Shafroth pairs) in multi-component Fermi systems
 remains a topical problem in a quantum many-body theory. Here this transition is studied by
 calculating the two-body density, spin and isospin correlation functions in dilute two-component
 Fermi superfluid, taking as an example an infinite system of protons and neutrons (nuclear matter).
 It is shown that criterion of the crossover (Phys. Rev. Lett. 95, 090402 (2005)), formulated
 for ultracold fermionic atomic gases and consisting in the change of the sign of the density correlation
 function at low momentum transfer, fails to describe correctly the density-driven BEC–BCS
 transition at finite isospin asymmetry or finite temperature. As an unambiguous signature of the
 BEC–BCS transition, one can use the presence (BCS regime) or absence (BEC regime) of the singularity
 in the momentum distribution of the quasiparticle density of states.