  A solution to the classical field equations in the massless (1+1)-dimensional
O(3) sigma model is found, which describes a multi-particle instanton-like
transition at high energy. In the limit of small number of initial particles,
the number of final particles is shown to be also small, and the probability of
the transition is suppressed by $\exp(-2S_0)$, where $S_0$ is the instanton
action. This solution, however, does not correspond to the maximum transition
probability among all states with given number of incoming particles and
energy. Unless the limit $g^2 n_{initial}\to0$ is exponentially sensitive to
the structure of the initial state, our results imply that well above the
sphaleron energy, the instanton-induced cross section becomes again suppressed
by the instanton exponent, and the number of final paricles is again small.
