Diagrammatic method of integration over the unitary group, with   applications to quantum transport in mesoscopic systems
  A diagrammatic method is presented for averaging over the circular ensemble of random-matrix theory. The method is applied to phase-coherent conduction through a chaotic cavity (a ``quantum dot'') and through the interface between a normal metal and a superconductor. 
P. W. Brouwer and C. W. J. Beenakker