Experimental Predictions of Lattice and Perturbative Quantum Chromodynamics

We discuss several experimental consequences of a lattice-gauge-theory calculation of the first two moments of the $\pi$ and $\rho$ distribution amplitudes. The second moments for both mesons are considerably larger than the values obtained from QCD sum-rule techniques. We show the qualitative difference that this makes in the predicted distribution amplitude, and demonstrate the consequences for the pion form factor and the $\gamma \gamma \to {\pi }^0{\pi }^0$ cross section.