Original article at: http://www.math.washington.edu/~ejpecp/viewarticle.php?id=2007

Intermittency on catalysts: three-dimensional simple symmetric exclusion

Jürgen Gärtner, Institut für Mathematik, Technische Universität Berlin
Frank den Hollander, Mathematical Institute, Leiden University
Grégory Maillard, CMI-LATP, Université de Provence

Abstract

We continue our study of intermittency for the parabolic Anderson model, ∂u ⁄ ∂ t = κΔu + ξu in a space-time random medium ξ, where κ is a positive diffusion constant, Δ is the lattice Laplacian on Zd, d≥1, and ξ is a simple symmetric exclusion process on Zd in Bernoulli equilibrium. This model describes the evolution of a "reactant" u under the influence of a "catalyst" ξ.

In Gärtner, den Hollander and Maillard [3] we investigated the behavior of the annealed Lyapunov exponents, i.e., the exponential growth rates as t → ∞ of the successive moments of the solution u. This led to an almost complete picture of intermittency as a function of d and κ. In the present paper we finish our study by focussing on the asymptotics of the Lyapunov exponents as κ → ∞ in the critical dimension d=3, which was left open in [3] and which is the most challenging. We show that, interestingly, this asymptotics is characterized not only by a Green term, as in d≥ 4, but also by a polaron term. The presence of the latter implies intermittency of all orders above a finite threshold for κ.


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Original article at: http://www.math.washington.edu/~ejpecp/viewarticle.php?id=2007