相关论文: Designing Cyclic Universe Models

We explore some issues in slow roll inflation in situations where field excursions are small compared to $M_p$. We argue that for small field inflation, minimizing fine tuning requires low energy supersymmetry and a tightly constrained…

In addition to generating the appropriate perturbation power spectrum, an inflationary scenario must take into account the need for inflation to end subsequently. In the context of single-field inflation models where inflation ends by…

We show that the cosmological evolution of a scalar field in a potential can be obtained from a renormalisation group equation. The slow roll regime of inflation models is understood in this context as the slow evolution close to a fixed…

We demonstrate that the strict upper bounds on the energy scale of inflation and on the tensor-to-scalar ratio can be somewhat relaxed if we assume that - after an initial period of slow rolling when scales probed today in CMB experiments…

We often find in the literature solutions to the Friedmann and fluid equations for simple cosmological models during the matter, radiation or cosmological constant dominated epochs. However no solutions appear for the inflationary era…

We offer a geometric interpretation of attractor theories with singular kinetic terms as a union of multiple canonical models. We demonstrate that different domains (separated by poles) can drastically differ in their phenomenology. We…

Inflationary cosmology explains the homogeneity and large-scale structure of the universe through a brief epoch of accelerated expansion following the Big Bang. Cyclic cosmologies, in contrast, describe a universe undergoing successive…

We obtain cosmological constraints on models of inflation which exhibit rapid roll solutions. Rapid roll attractors exist for potentials with large mass terms and are thus of interest for inflationary model building within string theory. We…

An algorithm is used to generate new solutions of the scalar field equations in homogeneous and isotropic universes. Solutions can be found for pure scalar fields with various potentials in the absence and presence of spatial curvature and…

We calculate power spectra of cosmological perturbations at high accuracy for two classes of inflation models. We classify the models according to the behaviour of the Hubble distance during inflation. Our approximation works if the Hubble…

The inflationary and pre-inflationary evolution of scalar modes of cosmological perturbations in a closed universe is analyzed for a loop quantum cosmology model with an inflationary regime consistent with the constraints on inflation…

The latest results from PLANCK impose strong constraints on features in the spectrum of the curvature perturbations from inflation. We analyse the possibility of particle production induced by sharp turns of the trajectory in field space in…

We investigate a particle physics model for cosmic inflation based on the following assumptions: (i) there are at least two complex scalar fields; (ii) the scalar potential is bounded from below and remains perturbative up to the Planck…

Models of cosmic inflation suggest that our universe underwent an early phase of accelerated expansion, driven by the dynamics of one or more scalar fields. Inflationary models make specific, quantitative predictions for several observable…

Modern data is showing increasing evidence that the Universe is accelerating. So far, all attempts to account for the acceleration have required some fundamental dimensionless quantities to be extremely small. We show how a class of scalar…

Two extensions of ideas lying in the basis of the inflationary scenario of the early Universe and their effect on the large scale structure of the present-day Universe are discussed. The first of them is the possibility of fast phase…

In the slow-roll inflationary scenario, the amplitude of the curvature perturbations approaches a constant value soon after the modes leave the Hubble radius. However, relatively recently, it was shown that the amplitude of the curvature…

The ekpyrotic and cyclic universe scenarios have revived the idea that the density perturbations apparent in today's universe could have been generated in a `pre-singularity' epoch before the big bang. These scenarios provide explicit…

A scenario with two subsequent periods of inflationary expansion in the very early universe is examined. The model is based on a potential motivated by symmetries being found in field theory at high energy. For various parameter sets of the…

We find the best-fit cosmological parameters for a scenario of inflation with only the sufficient amount of accelerated expansion for the $\lambda\phi^4$ potential. While for the simplest scenario of chaotic inflation all observable…