  We consider forced tunneling in QCD, described semiclassically by
instanton-antiinstanton field configurations. By separating topologically
different minima we obtain details of the effective potential and study the
turning states, which are similar to the sphaleron solution in electroweak
theory. These states are alternatively derived as minima of the energy under
the constraints of fixed size and Chern-Simons number. We study, both
analytically and numerically, the subsequent evolution of such states by
solving the classical Yang-Mills equations in real time, and find that the
gauge field strength is quickly localized into an expanding shell of radiating
gluons. The relevance to high-energy collisions of hadrons and nuclei is
briefly discussed.
