Deflationary Universe Scenario

We show that it is possible to realize an inflationary scenario even without conversion of the false vacuum energy to radiation. Such cosmological models have a deflationary stage in which $Ha^2$ is decreasing and radiation produced by particle creation in an expanding Universe becomes dominant. The preceding inflationary stage ends since the inflaton potential becomes steep. False vacuum energy is finally (partly) converted to the inflaton kinetic energy , the potential energy rapidly decreases and the Universe comes to the deflationary stage with a scale factor $a(t) \propto t^{1/3}$. Basic features and observational consequences of this scenario are indicated.