A New Equation of State for Dark Energy Model
  A new parameterization for the dark energy equation of state(EoS) is proposed
and some of its cosmological consequences are also investigated. This new
parameterization is the modification of Efstathiou' dark energy EoS
parameterization. $w (z)$ is a well behaved function for $z\gg1$ and has same
behavior in $z$ at low redshifts with Efstathiou' parameterization. In this
parameterization there are two free parameter $w_0$ and $w_a$. We discuss the
constraints on this model's parameters from current observational data. The
best fit values of the cosmological parameters with $1\sigma$ confidence-level
regions are: $\Omega_m=0.2735^{+0.0171}_{-0.0163}$,
$w_0=-1.0537^{+0.1432}_{-0.1511}$ and $w_a=0.2738^{+0.8018}_{-0.8288}$.
