Direct processes in chaotic microwave cavities in the presence of absorption -: art. no. 144101

We quantify the presence of direct processes in the S matrix of chaotic microwave cavities with absorption in the one-channel case. To this end the full distribution P-S(S) of the S matrix, i.e., S = root Re-i theta, is studied in cavities with time-reversal symmetry for different antenna coupling strengths T-a or direct processes. The experimental results are compared with random-matrix calculations and with numerical simulations including absorption. The theoretical result is a generalization of the Poisson kernel. The experimental and the numerical distributions are in excellent agreement with theoretical predictions for all cases.