The Coleman-Weinberg effective potential in the theory of   superconductivity
  A quasi two-dimensional non-relativistic four-Fermi theory is studied at finite temperatures in the next-to-leading order approximation using the Coleman-Weinberg effective potential. The appearance of an imaginary part to the one-loop correction is discussed in the context of condensed matter theory where it is referred to as the Thouless criterion for superconductivity. By reference to the appropriate modified effective potential one may revise the Thouless criterion to obtain a critical temperature in next-to-leading order that, unlike the mean-field temperature, tends to zero in the two-dimensional limit in agreement with the Coleman theorem. 
Rachel M. Quick and Sergei G. Sharapov