Semiclassical Transition in φ 4 Theory ∗

We have shown an example of semiclassical transition in φ4 theory with positive coupling constant. This process can be described by the classical O(4)-invariant solution, considered on a contour in the complex time plane. The transition is technically analogous to the oneinstanton transition in the electroweak model. It is suppressed by the factor exp(−2S0) , where S0 is Lipatov instanton action. This process describes a semiclassical transition between two coherent states with much smaller number of particles in the initial state than in the final state. Therefore, it could be relevant to the problem of calculation of amplitudes for multiparticle production in φ4-type models. Work supported in part by the National Science Foundation under grant PHY-9096198. [email protected]