Scattering length of composite bosons in the three-dimensional BCS-BEC crossover
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; EVOLUTIONDOI: 10.1103/PhysRevA.91.033610Citations: 3data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2021-10-17References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here