On cable-graph percolation between dimensions 2 and 3
Pierre-François Rodriguez, Wen Zhang
TL;DR
The paper analyzes cable-graph percolation for the Gaussian free field on 2D slabs of height h_N, bridging two- and three-dimensional behaviors by compactifying one dimension and studying the resulting slab model. A decomposition of the field into two- and three-dimensional components, coupled with precise Green’s function and capacity estimates on slabs, reveals a spectrum of fixed points and a plateau in the one-arm decay in the delocalized phase. It provides sharp lower and upper bounds for crossing probabilities, leveraging obstacle-based methods, killed Green’s functions, and loop-soup isomorphisms to handle the mixed-dimensional regime. The results illuminate a logarithmic-to-polynomial transition between dimensions 2 and 3 and introduce a detailed framework that can accommodate a wide range of slab heights, including thin limits, with implications for universality classes beyond polynomial scaling. Overall, the work advances a rigorous, parameter-robust ε-expansion perspective for cable-system percolation in mixed-dimensional settings.
Abstract
We consider the Gaussian free field on two-dimensional slabs with a thickness described by a height $h$ at spatial scale $N$. We investigate the radius of critical clusters for the associated cable-graph percolation problem, which depends sensitively on the parameter $h$. Our results unveil a whole family of new "fixed points", which interpolate between recent results from arXiv:2303.03782 in two dimensions and from arXiv:2405.17417 and arXiv:2406.02397 in three dimensions, and describe critical behaviour beyond those regimes. In the delocalised phase, the one-arm decay exhibits a "plateau", i.e. it doesn't depend on the speed at which the variance of the field diverges in the large-$N$ limit. Our methods rely on a careful analysis of the interplay between two- and three-dimensional effects for the underlying random walk, which manifest themselves in a corresponding decomposition of the field.
