2007/01/02 by H. S. Køhler, H. S. Kohler, Kohler, H. S.
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Advanced NMR Techniques and Applications #Astrophysics (astro-ph) #FOS: Physical sciences #Nuclear Theory (nucl-th) #Other Condensed Matter (cond-mat.other) #Physics of Superconductivity and Magnetism #astro-ph #cond-mat.other #nucl-th
paper · pdf · doi:10.48550/arxiv.nucl-th/0701006
11 pages and 4 figures; This paper will be revised due to a error in computer-program
openalex publication_date 2007/01/02 · arxiv created 2007/05/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The energy shift due to the interaction of two particles in a large box is proportional to the free particle scattering phase-shift. This provides an approximation to the effective interaction referred to as the phase-shift approximation. For a many-body fermion system this effective interaction has to be corrected for the Pauli-blocking. It is used to calculate the energy of a spin 1/2 fermion system as a function of the two-body scattering length and effective range. In the unitary limit with scattering length going to infinity and effective range going to zero the energy is 0.540 (in the units of the non-interactiong fermi gas energy) with a pp-ladder summation. Including hh-ladders the energy is 0.570. A smooth crossover from the BCS to the BEC region is observed. Pairing is not included.