2007/03/31 by Lianyi He, Pengfei Zhuang · 3 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism #Quantum, superfluid, helium dynamics #cond-mat.supr-con #hep-ph #hep-th #nucl-th
paper · pdf · doi:10.1103/physrevd.75.096003
published as Phys.Rev.D75:096003,2007 · 8 pages, 3 figures. V2: typos corrected, a comment on mean field theory added
arxiv created 2007/04/18 · openalex publication_date 2007/05/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate the BCS-BEC (Bardeen-Cooper-Shriffer---Bose-Einstein condensation) crossover at zero temperature in the frame of a relativistic model. The universality of the BCS-BEC crossover for nonrelativistic systems breaks down in the relativistic case and the crossover can be induced by changing the density. When the effective scattering length is much less than the fermion Compton wavelength, we recover the nonrelativistic result if the gas is initially in a nonrelativistic state. At ultrastrong coupling where the scattering length is of the order of the Compton wavelength, a new BEC state appears. In this state the condensed bosons become nearly massless and antifermions are excited. The behavior of the Goldstone mode and the mixing between the amplitude and phase modes are significantly different in different condensed regions.