Large-$N$ expansion for the time-delay matrix of ballistic chaotic   cavities
  We consider the $1/N$-expansion of the moments of the proper delay times for a ballistic chaotic cavity supporting $N$ scattering channels. In the random matrix approach, these moments correspond to traces of negative powers of Wishart matrices. For systems with and without broken time reversal symmetry (Dyson indices $\beta=1$ and $\beta=2$) we obtain a recursion relation, which efficiently generates the coefficients of the $1/N$-expansion of the moments. The integrality of these coefficients and their possible diagrammatic interpretation is discussed. 
Fabio Deelan Cunden, Francesco Mezzadri, Nick Simm and Pierpaolo Vivo
math-ph cond-mat.mes-hall cond-mat.stat-mech math.MP