The presence of a scalar field is motivated by ideas in high
energy physics and quantum gravities, although it has notbeen discovered experimentally. TeV-scale experiments at
LHC and Tevatron might be able to confirm its existence. It
is nevertheless widely accepted in several theoretical modeling frameworks, especially in contemporary cosmology of
which an early-time accelerating expansion, the inflation is
proposed to be driven by a scalar field in order to solve horizon and flatness problems (Starobinsky1980;Guth1981;
Sato1981;AlbrechtandSteinhardt1982;Linde1982). After inflation, components of barotropic fluids such as radiation and other non-relativistic matter were produced during
reheating and cooling-down processes. The present universe
is also found to be in acceleration phase which is strongly
backed up by various observations, e.g. the cosmic microwave background (Masi et al.2002), large-scale structure
surveys (Scranton et al.2003)andsupernovae(SN)typeIa
observations (Riess et al.1998,2004,2007;Perlmutteretal.
1999;Riess1999;Goldhaberetal.2001;Tonryetal.2003;
Astier et al.2006). The scalar field could be responsible to
the present acceleration in various models of dark energy
(Padmanabhan2005,2006;Copelandetal.2006).