Coupled Electrons and Pair Fluctuations in Two Dimensions: A Transition to Superconductivity in a Conserving Approximation

Abstract

We report a superconducting transition in the fully conserving fluctuation exchange approximation for a two-dimensional attractive Hubbard model. The transition temperature agrees well with quantum Monte Carlo calculations, but the superfluid density and specific heat near ${T}_{c}$ have anomalous temperature dependences for lattice sizes up to $64\ifmmode\times\else\texttimes\fi{}64$.