Nonperturbative renormalization group for the Kardar-Parisi-Zhang equation.

We present a simple approximation of the nonperturbative renormalization group designed for the Kardar-Parisi-Zhang equation and show that it yields the correct phase diagram, including the strong-coupling phase with reasonable scaling exponent values in physical dimensions. We find indications of a possible qualitative change of behavior around d=4. We discuss how our approach can be systematically improved.