Numerical evidence for stretched exponential relaxations in the Kardar-Parisi-Zhang equation

We present results from extensive numerical integration of the Kardar-Parisi-Zhang (KPZ) equation in 1+1 dimensions aimed to check the long-time behavior of the dynamical structure factor of that system. Over a number of decades in the size of the structure factor we confirm scaling and stretched exponential decay. We also give an analytic expression that yields a very good approximation to the numerical data. Our result clearly favors stretched exponential decay over recent results claiming to yield the exact time dependent structure factor of the 1+1-dimensional KPZ system. We suggest a possible solution to that contradiction.