  We consider the process of decay of symmetric vacuum state as evaporation of
a Bose condensate of physical Higgs particles, defined over asymmetric vacuum
state. Energy density of their selfinteraction is identified with cosmological
constant $\Lambda$ in the Einstein equation. $\Lambda$ decay then provides
dynamical realization of spontaneous symmetry breaking. The effective mechanism
is found for damping of coherent oscillations of a scalar field, leading to
slow evaporation regime as the effective mechanism for $\Lambda$ decay
responsible for inflation without special fine-tuning of the microphysical
parameters. This mechanism is able to incorporate reheating, generation of
proper primordial fluctuations, and nonzero cosmological constant today.
