Pairing fluctuations and pseudogap effects in the BCS–BEC crossover regime of a superfluid Fermi gas

Abstract

We study effects of strong pairing fluctuations on single-particle properties of a superfluid Fermi gas in the BCS–BEC crossover region. Including phase and amplitude fluctuations of the order parameter within the T-matrix approximation, we calculate the superfluid density of states below the superfluid phase transition temperature Tc. We show how the pseudogap appearing in the normal phase above Tc changes into the superfluid gap over the entire BCS–BEC crossover region, as one passes through Tc.