A class of transient acceleration models consistent with Big Bang
  Cosmology
  Is it possible that the current cosmic accelerating expansion will turn into
a decelerating one? Can this transition be realized by some viable theoretical
model that is consistent with the standard Big Bang cosmology? We study a class
of phenomenological models of a transient acceleration, based on a dynamical
dark energy with a very general form of equation of state
$p_{de}=\alpha\rho_{de}-\beta\rho_{de}^m$. It mimics the cosmological constant
$\rho_{de}\rightarrow$ const for small scale factor $a$, and behaves as a
barotropic gas with $\rho_{de}\rightarrow a^{-3(\alpha+1)}$ with $\alpha\ge 0$
for large $a$. The cosmic evolution of four models in the class has been
examined in details, and all yields a smooth transient acceleration. Depending
on the specific model, the future universe may be dominated either by the dark
energy or by the matter. In two models, the dynamical dark energy can be
explicitly realized by a scalar field with an analytical potential $V(\phi)$.
Moreover, the statistical analysis shows that the models can be as robust as
$\Lambda$CDM in confronting the observational data of SN Ia, CMB, and BAO. As
improvements over the previous studies, our models overcome the over-abundance
problem of dark energy during early eras, and satisfy the constraints on the
dark energy from WMAP observations of CMB.
