Critical percolation on slabs with random columnar disorder
Matheus B. Castro, Rémy Sanchis, Roger W. C. Silva
TL;DR
This work analyzes bond percolation on a 3D slab with columnar disorder driven by a heavy-tailed renewal process. The authors develop a multiscale renormalization tailored to heavy-tailed environments, proving that when the enhanced-column probability $q$ is supercritical and the renewal tail exponent $\\phi$ is large enough (depending on the slab thickness $k$), percolation occurs at a horizontal bond probability $p$ strictly below the critical threshold $p_c(\\mathbb{S}^+_k)$. A key contribution is a polynomial upper bound on the slab correlation length $L_\\tau(p)$ in terms of $|p-p_c|$, achieved via a combination of pivotal-edge analysis, Gluing Lemmas, and a 1-dependent renormalized percolation coupled to a Marcos-style multiscale scheme. The results illuminate near-critical behavior in disordered 3D systems with infinite-range vertical dependencies and provide a framework for extending near-critical percolation methods to slab geometries with heavy-tailed columnar disorder. The findings have potential implications for understanding connectivity in heterogeneous materials and networks where rare but strong inhomogeneities govern global connectivity.
Abstract
We explore a bond percolation model on slabs $\mathbb{S}^+_k=\mathbb{Z}_+\times \mathbb{Z}_+\times\{0,\dots,k\}$ featuring one-dimensional inhomogeneities. In this context, a vertical column on the slab comprises the set of vertical edges projecting to the same vertex on $\mathbb{Z}_+\times\{0,\dots,k\}$. Columns are chosen based on the arrivals of a renewal process, where the tail distributions of inter-arrival times follow a power law with exponent $φ>1$. Inhomogeneities are introduced as follows: vertical edges on selected columns are open (closed) with probability $q$ (respectively $1-q$), independently. Conversely, vertical edges within unselected columns and all horizontal edges are open (closed) with probability $p$ (respectively $1-p$). We prove that for all sufficiently large $φ$ (depending solely on $k$), the following assertion holds: if $q>p_c(\mathbb{S}^+_k)$, then $p$ can be taken strictly smaller than $p_c(\mathbb{S}^+_k)$ in a manner that percolation still occurs.
