Effective models of inflation from a non-local framework
  The dilaton is a possible inflaton candidate following recent CMB data
allowing a non-minimal coupling to the Ricci curvature scalar in the early
Universe. In this paper, we introduce an approach that has seldom been used in
the literature, namely dilaton inflation with non-local features. More
concretely, employing non-local features expressed in J. High Energy Phys. 04
(2007) 029, we study quadratic variations around a de Sitter geometry of an
effective action with a non-local dilaton. The non-locality refers to an
infinite derivative kinetic term involving the operator
$\mathcal{F}\left(\Box\right)$. Algebraic roots of the characteristic equation
$\mathcal{F}(z)=0$ play a crucial role in determining the properties of the
theory. We subsequently study the cases when $\mathcal{F}\left(\Box\right)$ has
one real root and one complex root, from which we retrieve two concrete
effective models of inflation. In the first case we retrieve a class of single
field inflations with universal prediction of $n_{s}\sim0.967$ with any value
of the tensor to scalar ratio $r<0.1$ intrinsically controlled by the root of
the characteristic equation. The second case involves a new class of two field
conformally invariant models with a peculiar quadratic cross-product of scalar
fields. In this latter case, we obtain Starobinsky like inflation through a
spontaneously broken conformal invariance. Furthermore, an uplifted minimum of
the potential, which accounts for the vacuum energy after inflation is produced
naturally through this mechanism intrinsically within our approach.
