Minimal model for anomalous diffusion.

A random walk model with a local probability of removal is solved exactly and shown to exhibit subdiffusive behavior with a mean square displacement the evolves as 〈x^{2}(t)〉∼t^{1/2} at late times. This model is shown to be well described by a diffusion equation with a sink term, which also describes the evolution of a pressure or temperature field in a leaky environment. For this reason a number of physical processes are shown to exhibit anomalous diffusion. The presence of the sink term is shown to change the late time behavior of the field from 1/t^{1/2} to 1/t^{3/2}.