Related papers: Preventing eternality in phantom inflation

We study general $f(R,\phi)$ theories in Palatini formalism and attempt to constrain the behavior of ones that could support both inflationary and late-time expansion era in a unified model. In particular, we find conditions for which the…

We consider curved space quantum corrections to the equations of motion of the inflaton field in the early Universe. Using the stochastic formalism in phase space, we demonstrate that the quantum corrected evolution of the inflaton can…

Eternally inflating universes can contain thermalized regions with different values of the cosmological parameters. In particular, the spectra of density fluctuations should be different, because of the different realizations of quantum…

We investigate, in a model-independent way, the conditions required to obtain a satisfactory model of extended inflation in which inflation is brought to an end by a first-order phase transition. The constraints are that the correct present…

In this paper, we show that eternal inflation of the random walk type is generically absent in the brane inflationary scenario. Depending on how the brane inflationary universe originated, eternal inflation of the false vacuum type is still…

We consider eternal inflation in hilltop-type inflation models, favored by current data, in which the scalar field in inflation rolls off of a local maximum of the potential. Unlike chaotic or plateau-type inflation models, in hilltop…

We apply the criterion of finite naturalness to the limiting case of a generic heavy sector decoupled from the Standard Model. The sole and unavoidable exception to this decoupling arises from gravitational interactions. We demonstrate that…

This review article aims at presenting the theory of inflation. We first describe the background spacetime behavior during the slow-roll phase and analyze how inflation ends and the Universe reheats. Then, we present the theory of…

We review here some recent results that show that inflationary cosmological models must contain initial singularities. We also present a new singularity theorem. The question of the initial singularity re-emerges in inflationary cosmology…

Slow-roll inflation can become eternal if the quantum variance of the inflaton field around its slowly rolling classical trajectory is converted into a distribution of classical spacetimes inflating at different rates, and if the variance…

Eternal inflation is shown to require violations of the Null Energy Condition (NEC) on superhorizon scales. With light scalar fields as the matter sources in a de Sitter background, there can be no classical or semiclassical violations of…

Inflation has been the leading early universe scenario for two decades, and has become an accepted element of the successful `cosmic concordance' model. However, there are many puzzling features of the resulting theory. It requires both…

Eternal inflation is a seemingly generic consequence of theories that give rise to accelerated expansion of the universe and possess multiple vacuum states. Making predictions in an eternally inflating universe is notoriously difficult…

The mechanism of thermal inflation, a relatively short period of accelerated expansion after primordial inflation, is a desirable ingredient for a certain class of particle physics models if they are not to be in contention with the…

We continue to investigate possible parameter choices for primordial inflation with simple potentials such as power-law and two-term potentials. We examine the amount of parameter tuning to make the slow-roll inflation eternal. In…

We propose a new framework for multi-field inflation in which a nearly constant potential energy is maintained during inflation before decreasing rapidly, in a manner analogous to a classical top spinning upright for a long time before…

We revisit an inflationary scenario in which primordial inhomogeneities arise from a quantum collapse, a stochastic mechanism described in the context of quantum collapse theories in its continuous version and within semiclassical gravity.…

The effects of the gravitational back reaction of cosmological perturbations are investigated in a phantom inflation model. The effective energy-momentum tensor of the gravitational back reaction of cosmological perturbations whose…

Many inflating spacetimes are likely to violate the weak energy condition, a key assumption of singularity theorems. Here we offer a simple kinematical argument, requiring no energy condition, that a cosmological model which is inflating --…

We investigate whether inflation requires finely tuned initial conditions in order to explain the degree of flatness and homogeneity observed in the Universe. We achieve this by using the Eisenhart lift, which can be used to write any…