A common origin of two accelerating universes: inflation and dark energy

We develop a quantum theory of inflaton and its decay product of various gauge boson pairs to investigate the preheating towards thermalized universe. The inflaton decay into gauge-boson pairs is shown to be inevitably accompanied by tachyon-mass-like correction to inflation potential that ultimately leads to an inflaton escape out of trapped local potential minimum towards the field infinity. This gives rise to a conversion mechanism of early inflationary acceleration to a quintessence dark energy acceleration at late stages of cosmic evolution. The success of the escape depends on how standard particles are incorporated into a scheme of extended Jordan-Brans-Dicke gravity. New types of super-radiance mechanism that enhance the ending of preheating are identified and compared with the Dicke model.