Numerical study of induced false vacuum decay at high energies

We calculate numerically the probability exp[1/lambda F(E/E(sph), N/N-sph)] of the false vacuum decay in the massive four-dimensional -lambda phi(4) from multiparticle initial states with fixed number of particles N whose total energy E is of order or greater than the height of the barrier E(sph). We find that at E less than or similar to 3E(sph) and N less than or similar to 0.4N(sph) the decay is classically forbidden and thus is exponentially suppressed. We argue that the classically forbidden region extends, at small N, at least up to E similar to 10E(sph) and, most likely, to all energies. Our data suggest that the false vacuum decay induced by two-particle collisions is exponentially suppressed at all energies.