A Natural Solution to the Dark Energy Problem

Recent observations indicate that the acceleration of our universe expansion is slowing down, which challenge the standard CDM model. In this article, we show that the existence of particles with imaginary energy density can explain the observed slowing down acceleration and provide a complete solution to the origin of dark energy. This model can give good agreements with observational constraints by 28 data from supernovae between redshift z = 0:07 - 2:3.