It has long been known that the critical temperature of a BCS weak-coupling superfluid gets considerably reduced when the Gorkov-Melik-Barkhudarov (G-MB) correction is considered, whereby particle-hole excitations affect the two-fermion scattering in the medium responsible for the formation of Cooper pairs. Here, by a careful analysis which takes into account the wave-vector and frequency dependence of the pair propagator (which gets increasingly important away from the weak coupling limit where the G-MB correction was originally derived) we extend the effects of the G-MB correction throughout the BCSBEC crossover. In particular, the Feynman diagram responsible for the G-MB correction is inserted in a partially self-consistent T-matrix scheme; the resulting equations are solved numerically and yield a curve for the critical temperature which agrees very well with the Quantum Monte Carlo data available in the crossover region.

Effects of the GMB correction on the critical temperature throughout the BCS-BEC crossover

PISANI, Leonardo;A. Perali;P. Pieri;G. Strinati Calvanese
2017-01-01

Abstract

It has long been known that the critical temperature of a BCS weak-coupling superfluid gets considerably reduced when the Gorkov-Melik-Barkhudarov (G-MB) correction is considered, whereby particle-hole excitations affect the two-fermion scattering in the medium responsible for the formation of Cooper pairs. Here, by a careful analysis which takes into account the wave-vector and frequency dependence of the pair propagator (which gets increasingly important away from the weak coupling limit where the G-MB correction was originally derived) we extend the effects of the G-MB correction throughout the BCSBEC crossover. In particular, the Feynman diagram responsible for the G-MB correction is inserted in a partially self-consistent T-matrix scheme; the resulting equations are solved numerically and yield a curve for the critical temperature which agrees very well with the Quantum Monte Carlo data available in the crossover region.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/407887
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