No infinite cluster at criticality for long-range percolation with fast-decaying interactions
We consider independent long-range bond percolation on $\mathbb{Z}^d$ in which $x$ and $y$ are joined with probability $1-e^{-βJ(x-y)}$. Let $d\ge2$ and let $J$ be invariant under coordinate permutations and sign changes, positive on nearest-neighbour pairs, and satisfy $\liminf_{n\to\infty} n^d\sum_{\|x\|>n}J(x)=0$. We prove that there is no infinite cluster at the critical parameter. Together with Berger's theorem for heavy tails, this gives continuity of the phase transition for $J(x)\asymp\|x\|^{-d-α}$ for every $α>0$ except $α=d$, in every dimension $d\ge2$, and for every exponentially decaying kernel satisfying these hypotheses. Previously the fast-decaying case was known for nearest-neighbour and uniform finite-range kernels, in $d=2$ for finite-range and exponential kernels, and in high dimension for sufficiently spread-out kernels. The proof adapts a recent renormalization argument for nearest-neighbour percolation on $\mathbb{Z}^3$ that is driven by a gluing inequality conjectured by Kozma and Nitzan. Long edges enter in two places: they can jump over the surfaces that a nearest-neighbour path must cross, and they let a cluster outside a box enter it from far away. We control the first with thick outer faces and the tail condition, and the second by measuring entrances through the total edge weight between a cluster and a box rather than through the number of boundary vertices.