Dark Energy Problem in a Four-Fermion Interaction Model

Cosmology enters precision testing period with the observational experiments advancement. We have not arrived to decipher the origin of the dominant dark energy component of our universe, although we have located some of its characters. In such a situation the possibilities of a simple four-fermion interaction model are investigated to describe dark energy characters. We explicitly calculate the vacuum expectation value of the energy-momentum tensor and discuss the results with comparison to the equation of state for dark energy requirement. It is found that the negative pressure is realized at low temperature. It is an appropriate property as a dark energy candidate. We also investigate some cosmological tests for the dark energy via its equation of state.