A lower bound for point-to-point connection probabilities in critical percolation

Abstract

Consider critical site percolation on ${\mathbb{Z}}^d$ with $d\ge 2$. We prove a lower bound of order $n^{-d^2}$ for point-to-point connection probabilities, where $n$ is the distance between the points. Most of the work in our proof concerns a `construction' which finally reduces the problem to a topological one. This is then solved by applying a topological fact, which follows from Brouwer's fixed point theorem. Our bound improves the lower bound with exponent $2d(d-1)$, used by Cerf in 2015 to obtain an upper bound for the so-called two-arm probabilities. Apart from being of interest in itself, our result gives a small improvement of the bound on the two-arm exponent found by Cerf.

13 pages