Dark energy model with higher derivative of Hubble parameter

In this Letter we consider a dark energy model in which the energy density is a function of the Hubble parameter H and its derivative with respect to time rho(de) = 3 alpha(H)double dotH(-1) + 3 beta(H)over dot + 3 gamma H-2. The behavior of the dark energy and the expansion history of the Universe depend heavily on the parameters of the model alpha, beta and gamma. It is very interesting that the age problem of the well-known three old objects can be alleviated in this models. (C) 2009 Elsevier B.V. All rights reserved.