Decoupling inequalities and interlacement percolation on <Emphasis Type="Italic">G</Emphasis>×ℤ

We study the percolative properties of random interlacements on G×ℤ, where G is a weighted graph satisfying certain sub-Gaussian estimates attached to the parameters α>1 and 2≤β≤α+1, describing the respective polynomial growths of the volume on G and of the time needed by the walk on G to move to a distance. We develop decoupling inequalities, which are a key tool in showing that the critical level u _∗ for the percolation of the vacant set of random interlacements is always finite in our set-up, and that it is positive when α≥1+β/2. We also obtain several stretched exponential controls both in the percolative and non-percolative phases of the model. Even in the case where G=ℤ ^d , d≥2, several of these results are new.