THE PROBLEM OF QUANTUM CHAOTIC SCATTERING WITH DIRECT PROCESSES REDUCED TO THE ONE WITHOUT

We show that the study of the statistical properties of the scattering matrix S for quantum chaotic scattering in the presence of direct pro cesses (characterized by (S) over bar not equal 0, (S) over bar being the average S-matrix) can be reduced to the simpler case where direct processes are absent ((S) over bar = 0). Our result is verified with a numerical simulation of the two-energy autocorrelation for two-dimens ional S-matrices. It is also used to extend Wigner's time delay distri bution for one-dimensional S-matrices, recently found for (S) over bar = 0, to the case (S) over bar not equal 0; this extension is verified numerically. As a consequence of our result, future calculations can be restricted to the simpler case of no direct processes.