Scientific Results

Scattering length of composite bosons in the three-dimensional BCS-BEC crossover

Year: 2015

Authors: Salasnich L., Bighin G.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, I-35131 Padua, Italy;‎ Consorzio Nazl Interuniv Sci Fis Mat, Unita Padova, I-35131 Padua, Italy; CNR, Sez Sesto Fiorentino, Ist Nazl Ott, I-50019 Sesto Fiorentino, Italy;‎ Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy

Abstract: We study the zero-temperature grand potential of a three-dimensional superfluid made of ultracold fermionic alkali-metal atoms in the BCS-BEC crossover. In particular, we analyze the zero-point energy of both fermionic single-particle excitations and bosonic collective excitations. The bosonic elementary excitations, which are crucial to obtain a reliable equation of state in the Bose-Einstein condensate regime, are obtained with a low-momentum expansion up to the forth order of the quadratic (Gaussian) action of the fluctuating pairing field. By performing a cutoff regularization and renormalization of Gaussian fluctuations, we find that the scattering length a(B) of composite bosons, bound states of fermionic pairs, is given by a(B) = (2/3) a(F), where a(F) is the scattering length of fermions.

Journal/Review: PHYSICAL REVIEW A

Volume: 91 (3)      Pages from: 033610-1  to: 033610-5

KeyWords: BOSE-CONDENSATION; FERMI GAS; SUPERCONDUCTIVITY; EVOLUTION
DOI: 10.1103/PhysRevA.91.033610

Citations: 3
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