  In this work, we consider critical planar site percolation on the triangular
lattice and derive sharp estimates on the asymptotics of the probability of
half-plane $j$-arm events for $j \geq 1$ and planar (polychromatic) $j$-arm
events for $j>1$. These estimates greatly improve previous results and in
particular answer (a large part of) a question of Schramm (ICM Proc., 2006).
