  Decay amplitudes for mesons in two-dimensional QCD are discussed. We show
that in spite of an infinite number of conserved charges, particle production
is not entirely suppressed. This phenomenon is explained in terms of quantum
corrections to the combined algebra of higher-conserved and spectrum-generating
currents. We predict the qualitative form of particle production probabilities
and verify that they are in agreement with numerical data. We also discuss
four-dimensional self-dual Yang-Mills theory in the light of our results.
