Abstract:
Quintessential inflation refers to scenarios in which a single scalar field is used to describe
inflation and late time acceleration. This review is dedicated to the framework of quintessential
inflation, with a focus on the building blocks of formalism. Consistent unification of inflation and
late time acceleration using a single scalar field asks for a shallow field potential initially followed
by steep behaviour thereafter and shallow again around the present epoch. The requirement of
non-interference of the scalar field with thermal history dictates the steep nature of potential in
the post-inflationary era, with a further restriction that late time physics be independent of initial
conditions. We describe, in detail, the scaling and asymptotic scaling solutions and the mechanism
of exit from the scaling regime to late time acceleration. The review includes a fresh look at scaling
solutions that are central to the theme of unification of inflation and late time acceleration. As
for the exit mechanism, special attention is paid to the coupling of massive neutrino matter to the
scalar field, which builds up dynamically and can give rise to late time acceleration. We present a
detailed analytical treatment of scalar field dynamics in the presence of coupling. We briefly discuss
the distinguishing feature of quintessential inflation, namely the blue spectrum of gravity waves
produced during the transition from inflation to the kinetic regime.
