Bose-Einstein condensation in the early universe

By introducing the Bose‐Einstein condensation dynamics (BEC), we develop a unified model of dark energy and dark matter. The two phases of BEC (= dark energy) and normal gas (= dark matter) transform with each other through the phase transition. We study the present mild acceleration, the inflation in the early universe, and the reduction of the cosmological constant. We find the stagflation regime when the cosmic expansion stops and the uniform mode of BEC becomes unstable. We also comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present.