STRETCHED-EXPONENTIAL RELAXATION - THE ROLE OF SYSTEM SIZE

We investigate the role of system size on stretched-exponential relaxa tion which arises from a convolution of two competing exponential proc esses. We find that above a cross-over time t(x) that depends logarith mically on the size of the system the relaxation changes from a stretc hed exponential to a single-exponential decay. The rate of the exponen tial also depends logarithmically on the system size. This anomalous s ize dependence is exemplified by the trapping problem and by the model of hierarchically constrained dynamics.