Abstract The Nobel Prize winning confirmation in 1998 of the accelerated expansion of our
Universe put into sharp focus the need of a consistent theoretical model to explain the origin …

After a decade and a half of research motivated by the accelerating universe, theory and
experiment have reached a certain level of maturity. The development of theoretical models …

We review in detail a number of approaches that have been adopted to try and explain the
remarkable observation of our accelerating universe. In particular we discuss the arguments …

Dark energy with the equation of state w (z) rapidly evolving from the dustlike (w≃ 0 at z∼ 1)
to the phantomlike (-1.2≲ w≲-1 at z≃ 0) has been recently proposed as the best fit for the …

Theoretical approaches to explaining the observed acceleration of the universe are
reviewed. We briefly discuss the evidence for cosmic acceleration, and the implications for …

I review the problem of dark energy focussing on cosmological constant as the candidate
and discuss what it tells us regarding the nature of gravity. Section 1 briefly overviews the …

We investigate a flat Friedmann-Robertson-Walker spacetime filled with k essence and find
the set of functions F that generate three different families of extended tachyon fields and …

The conceptual difficulties associated with a cosmological constant have led to the
investigation of alternative models in which the equation of state parameter, w= p/ρ, of the …

Scalar fields have played an important role in the development of the fundamental theories
of physics as well as in other branches of physics such as gravitation and cosmology. For a …

The dark energy component of the Universe is often interpreted either in terms of a
cosmological constant or as a scalar field. A generic feature of the scalar field models is that …