Long-range one-dimensional internal diffusion-limited aggregation

Conrado da Costa, Debleena Thacker, and Andrew Wade

Submitted.

Supported by EPSRC award Anomalous diffusion via self-interaction and reflection (EP/W00657X/1).

Abstract

We study internal diffusion limited aggregation on $\Z$, where a cluster is grown by sequentially adding the first site outside the cluster visited by each random walk dispatched from the origin. We assume that the increment distribution $X$ of the driving random walks has $\mathbb{E} X =0$, but may be neither simple nor symmetric, and can have $\mathbb{E} (X^2) = \infty$, for example. For the case where $\mathbb{E} (X^2) < \infty$, we prove that after $m$ walks have been dispatched, all but $o(m)$ sites in the cluster form an approximately symmetric contiguous block around the origin. This extends known results for simple random walk. On the other hand, if $X$ is in the domain of attraction of a symmetric $\alpha$-stable law, $1 < \alpha <2$, we prove that the cluster contains a contiguous block of $\delta m +o(m)$ sites, where $0 < \delta < 1$, but, unlike the finite-variance case, one may not take $\delta=1$.