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