Related papers: A geometric bound on F-term inflation
We present constraints on how far single field inflation may depart from the familiar slow-roll paradigm. Considering a fast-roll regime while requiring a (near)-scale-invariant power spectrum introduces large self-interactions for the…
We study single-field slow-roll inflation embedded in Palatini $F(R)$ gravity where $F(R)$ grows faster than $R^2$. Surprisingly, the consistency of the theory requires the Jordan frame inflaton potential to be unbounded from below. Even…
We study models of hybrid inflation in the framework of supergravity with superconformal matter. F-term hybrid inflation is not viable since the inflaton acquires a large tachyonic mass. On the contrary, D-term hybrid inflation can…
We study the possibility that inflation is driven by a scalar field together with a vector field minimally coupled to gravity. By assuming an effective potential that incorporates both fields into the action, we explore two distinct…
We study supergravity inflationary models where inflation is produced along the angular direction. For this we express the scalar component of a chiral superfield in terms of the radial and the angular components. We then express the…
We investigate the viability of a two-stage inflationary scenario in the context of supergravity, so as to resolve the problem of initial conditions for hybrid inflation. We allow for non-renormalizable terms in the superpotential and…
We analyse the consequences of a new gauge invariant Fayet-Iliopoulos (FI) term proposed recently to a class of inflation models driven by supersymmetry breaking with the inflaton being the superpartner of the goldstino. We first show that…
We study the dynamics of inflation in a generalized scalar-torsion gravity scenario by assuming a canonical scalar field non-minimally coupled to torsion with a Galileon-type self-interaction. After obtaining the field equations for a flat…
P-term inflation arises in some models of brane inflation. Within N=2 supersymmetry the scalar potential contains a vector of Fayet-Iliopoulos (FI) terms $\xi_i$. Depending on the direction of this vector it is possible to get D-term and…
We consider a class of well motivated supersymmetric models of F-term hybrid inflation (FHI) which can be linked to the supersymmetric grand unification. The predicted scalar spectral index n_s cannot be smaller than 0.97 and can exceed…
We show that inflation which is dominated by the D-term density avoids the `slow-roll' problem of inflation in supergravity. Such an inflationary scenario can naturally emerge in theories with non-anomalous or anomalous U(1) gauge symmetry.…
An alternative scenario about the phenomenology of primordial Universe is k-inflation. According to this concept, inflation can be achieved by nonstandard kinetic term of scalar field, namely the inflaton. In this project we focus on…
We investigate the possibility of obtaining inflationary solutions of the slow roll type from a low energy Lagrangian coming from superstrings. The advantage of such an approach is that in these theories the scalar potential has only one…
We examine the constraints on F-term hybrid inflation by considering the flat directions in the Minimal Supersymmetric Standard Model (MSSM). We find that some coupling terms between the flat direction fields and the field which dominates…
We show that in the simplest theories of spontaneous symmetry breaking one can have a stage of a fast-roll inflation. In this regime the standard slow-roll condition |m^2| << H^2 is violated. Nevertheless, this stage can be rather long if…
We study models of inflation where the inflaton corresponds to a flat direction in field space and its mass term is generated by gravity mediated soft supersymmetry breaking at high scale. Assuming the inflaton to have non negligible…
We take a pragmatic, model independent approach to single field slow-roll canonical inflation by imposing conditions, not on the potential, but on the slow-roll parameter $\epsilon(\phi)$ and its derivatives $\epsilon^{\prime }(\phi)$ and…
We derive an extended version of the well-known Lyth Bound on the total variation of the inflaton field, incorporating higher order corrections in slow roll. We connect the field variation $\Delta\phi$ to both the spectral index of scalar…
We shall investigate the inflation for the D-brane model, motivated by the modified gravity $F(\phi,T)$. This gravity has been recently introduced in the literature. The feasibility of the D-brane inflation theory in the $F(\phi,T)$-gravity…
We show how supersymmetric hybrid inflation with scalar spectral index $n_{\rm s}\simeq 0.96 - 0.97$ is realized in the context of quasi-minimal supergravity if we insist that the inflationary potential not exhibit any local minima. We also…