We provide a new proof of the sharpness of the phase transition for
nearest-neighbour Bernoulli percolation. More precisely, we show that
- for p<pc, the probability that the origin is connected by an open path
to distance n decays exponentially fast in n.
- for p>pc, the probability that the origin belongs to an infinite cluster
satisfies the mean-field lower bound θ(p)≥p(1−pc)p−pc.
This note presents the argument of \cite{DumTas15}, which is valid for
long-range Bernoulli percolation (and for the Ising model) on arbitrary
transitive graphs in the simpler framework of nearest-neighbour Bernoulli
percolation on Zd.