Reducing nonideal to ideal coupling in random matrix description of   chaotic scattering: Application to the time-delay problem
  We write explicitly a transformation of the scattering phases reducing the problem of quantum chaotic scattering for systems with M statistically equivalent channels at nonideal coupling to that for ideal coupling. Unfolding the phases by their local density leads to universality of their local fluctuations for large M. A relation between the partial time delays and diagonal matrix elements of the Wigner-Smith matrix is revealed for ideal coupling. This helped us in deriving the joint probability distribution of partial time delays and the distribution of the Wigner time delay. 
Dmitry V. Savin, Yan V. Fyodorov, Hans-Juergen Sommers