Analytic structure of the $3\to3$ forward amplitude

The analytic properties of the $3\to3$ forward amplitude established in the framework of Bogolyubov's axiomatic method are described. The amplitudes of the different channels of the process are the boundary values of a single analytic function of the invariant variables. Crossing symmetry of the amplitude is proved. The absorptive part of the amplitude is analyzed and a generalized optical theorem proved, this relating one of the contributions to the absorptive part to the distribution function of the inclusive process.