False vacuum decay induced by particle collisions

The semiclassical formalism for numerical calculation of the rate of tunneling transitions induced by N particles with total energy E of order or higher than the height of the barrier is developed. The formalism is applied to the induced false vacuum decay in the massive four-dimensional {minus}{lambda}{phi}{sup 4} model. The decay rate, as a function of E and N, is calculated numerically in the range 0.4{approx_lt}E/E{sub sph}{approx_lt}3.5 and 0.25{approx_lt}N/N{sub sph}{approx_lt}1.0, where E{sub sph} and N{sub sph} are the energy and the number of particles in the analogue of the sphaleron configuration. The results imply that the {ital two-particle} cross section of the false vacuum decay is exponentially suppressed at least up to energies of order 10E{sub sph}. At E{approximately}E{sub sph}, this exponential suppression is estimated as about 80{percent} of the zero energy suppression. {copyright} {ital 1997} {ital The American Physical Society}