MULTIPARTICLE SEMICLASSICAL PROCESS IN PHI(4) THEORY

We show an example of a semiclassical transition in phi4 theory with p ositive coupling constant. This process describes a semiclassical tran sition between two coherent states with much smaller average number of particles in the initial state than in the final state. This transiti on is technically analogous to the one-instanton transition in the ele ctroweak model. It is suppressed by the factor exp (-2S0), where S0 is the Lipatov instanton action. It could be important for the problem o f the calculation of amplitudes for multiparticle production in phi4-t ype models.