Related papers: k-Inflation
The previously proposed class of phenomenological inflationary models in which the assumption of inflaton slow-roll is replaced by the more general, constant-roll condition is compared with the most recent cosmological observational data,…
Inflation may have been driven by a component which violated the Null-Energy Condition, thereby leading to {\it super inflation}. We provide the formalism to study cosmological perturbations when such a component is described by a scalar…
We consider a novel model of cosmic inflation. In our model one does not need any specific matter field to drive inflation, but inflation stems from the microscopic, Planck scale structure of spacetime, thus being of quantum gravitational…
We consider k-inflation models where the action is a non-linear function of both the inflaton and the inflaton kinetic term. We focus on a scalar-tensor extension of k-inflation coupled to matter for which we derive a modified…
We explore the paradigm according to which inflation is driven by a four-dimensional strongly coupled dynamics coupled non-minimally to gravity. We start by introducing the general setup, both in the metric and Palatini formulation, for…
We consider non-canonical generalizations of two classes of simple single-field inflation models. First, we study the non-canonical version of "ultra-slow roll" inflation, which is a class of inflation models for which quantum modes do not…
We find successful models of D-brane/anti-brane inflation within a string context. We work within the GKP-KKLT class of type IIB string vacua for which many moduli are stabilized through fluxes, as recently modified to include `realistic'…
Solid inflation is a cosmological model where inflation is driven by fields which enter the Lagrangian in the same way as body coordinates of a solid matter enter the equation of state, spontaneously breaking spatial translational and…
It is sometimes argued that observation of tensor modes from inflation would provide the first evidence for quantum gravity. However, in the usual inflationary formalism, also the scalar modes involve quantised metric perturbations. We…
We study the quantum evolution of the early universe, its semi-classical analogue together with inflationary regime, in view of a generalized modified theory of gravity. The action is built by supplementing the non-minimally coupled…
In this paper we investigate the implications of having a varying second slow-roll index on the canonical scalar field inflationary dynamics. We shall be interested in cases that the second slow-roll can take small values and…
The conventional slow-roll approximation is broken in the so-called "ultra slow-roll" models of inflation, for which the inflaton potential is exactly (or extremely) flat. The interesting nature of (canonical) ultra slow-roll inflation is…
We consider a 4+N dimensional Einstein gravity coupled to a non-linear sigma model. This theory admits a solution in which the N extra dimensions contract exponentially while the ordinary space expand exponentially. Physically, the…
The Higgs field is an attractive candidate for the inflaton because it is an observationally confirmed fundamental scalar field. Importantly, it can be modeled by the most general renormalizable scalar potential. However, if the classical…
Inflation is the currently accepted paradigm for the beginnings of the Universe. To explain the observed almost scale invariant spectrum of density perturbations with only a slight spectral tilt, inflation must have been "slow roll", that…
We study preheating via kinetic couplings after dilaton-axion $\alpha$-attractor inflation. We focus on E-model $\alpha$-attractor driven inflation where the inflaton is kinetically coupled to an ultralight axion. In this class of models,…
In this paper we study a new class of inflation models which generalize the Dirac-Born-Infeld (DBI) action with the addition of a nonminimal kinetic coupling (NKC) term. We dubbed this model as the {\it new DBI inflation model}. The NKC…
I study two-stage hybrid inflation driven by moduli fields, corresponding to flat directions of supersymmetry, lifted by supergravity corrections. The first stage corresponds to a period of either fast-roll or `locked' inflation, induced by…
We study an inflationary scenario where thermal inflation is followed by fast-roll inflation. This is a rather generic possibility based on the effective potentials of spontaneous symmetry breaking in the context of particle physics models.…
We show that initial conditions for small-field inflation can be determined quantum mechanically by introducing a suitable flattened region in the scalar potential. The inflaton is then driven towards the slow-roll attractor solution…