Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Chinese Acad Sci, Interdisciplinary Ctr Theoret Studies, Beijing 100080, Peoples R China
Regarding long-life particle produced during preheating after inflation as dark matter, we find that its backreaction on the field phi can lock phi in a false vacuum up to today under certain conditions. This false vacuum can drive the accelerated expansion of universe at late time and play the role of dark energy. When the number density of dark matter particle is diluted to some value, the field phi will become tachyonic and roll to its true minimum rapidly, and the acceleration of universe ceases. We discuss the constraints on the parameters of model from the observations.