BCS-BEC Crossover Effects and Pseudogap in Neutron Matter
arXiv:2010.04672 · doi:10.3390/universe6110208
Abstract
Due to the large neutron-neutron scattering length, dilute neutron matter resembles the unitary Fermi gas, which lies half-way in the crossover from the BCS phase of weakly coupled Cooper pairs to the Bose-Einstein condensate of dimers. We discuss crossover effects in analogy with the T-matrix theory used in the physics of ultracold atoms, which we generalize to the case of a non-separable finite-range interaction. A problem of the standard Nozieres-Schmitt-Rink approach and different ways to solve it are discussed. It is shown that in the strong-coupling regime, the spectral function exhibits a pseudo-gap at temperatures above the critical temperature T_c. The effect of the correlated density on the density dependence of T_c is found to be rather weak, but a possibly important effect due to the reduced quasiparticle weight is identified.
16 pages; v2: minor changes, references added
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