Accelerating universe in two-dimensional noncommutative dilaton cosmology

We show that the phase transition from the decelerating universe to the accelerating universe, which is of relevance to the cosmological coincidence problem, is possible in the semiclassically quantized two-dimensional dilaton gravity by taking into account the noncommutative field variables during the finite time. Initially, the quantum-mechanically induced positive energy from the noncommutativity among the fields makes the early universe decelerating and subsequently the universe is accelerating because the dilaton driven cosmology becomes dominant later.