Effect of repulsion among fermion pairs on the problem of crossover between Cooper-pair and Bose-Einstein condensation

Abstract

Interpolation of the chemical potential μ in the Cooper-pair and the Bose-Einstein condensation, as increasing the strength of attraction among fermions, is discussed in 2D by extending Nozières and Schmitt-Rink's theory so as to include the repulsion among fermion pairs along the self-consistent renormalization approximation scheme. It is shown in the weak attraction limit that the repulsion makes the solution with negative chemical potential μ < 0 and T c = 0 unstable and pushes up μ toward the Fermi energy of non-interacting system.