Exact Perturbations for Inflation with Smooth Exit

Toy models for the Hubble rate or the scalar field potential have been used to analyze the amplification of scalar perturbations through a smooth transition from inflation to the radiation era. We use a Hubble rate that arises consistently from a decaying vacuum cosmology, which evolves smoothly from nearly de Sitter inflation to radiation domination. We find exact solutions for super-horizon perturbations (scalar and tensor), and for sub-horizon perturbations in the vacuum- and radiation-dominated eras. The standard conserved quantity for super-horizon scalar perturbations is exactly constant for the growing modes, and zero for the decaying modes.     

Inflation and the Rotation Problem

The effect of an inflaton scalar field on cosmic rotation is discussed. It is shown that any physically reasonable inflaton scalar will dilute the cosmic vorticity by a factor of R^?3γ when the false vacuum decays into matter. Since vorticity decays during inflation as R^3γ-5, this leads to a total decay by a factor of R⁵, which is not dependent on the equation of state of the rotating non-vacuum component of the energy-momentum tensor.     

Graceful exit from inflation using quantum cosmology

A massless scalar field without self-interaction and string coupled to gravity is quantized in the framework of quantum cosmology using the Bohm–de Broglie interpretation. Gaussian superpositions of the quantum solutions of the corresponding Wheeler–DeWitt equation in minisuperspace are constructed. The Bohmian trajectories obtained exhibit a graceful exit from the inflationary pre-big bang epoch to the decelerated expansion phase.     

LETTER: Warm Inflation: Towards a Realistic COBE Data Power Spectrum for Matter and Metric Thermal Coupled Fluctuations

I consider the COBE data coarse–grained field that characterize the now observable universe for a model of warm inflation which takes into account the thermally coupled fluctuations of the scalar field with the thermal bath. The power spectrum for both, matter and metric fluctuations are analyzed. I find that the amplitude for the fluctuations of the metric during the horizon entry should be very small for the expected values of temperature.     

Inflation without Selfreproduction

We find a rather unique extension of inflationary scenario which avoids selfreproduction and thus resolves the problems of multiverse, predictability and initial conditions. In this theory the amplitude of the cosmological perturbations is expressed entirely in terms of the total duration of inflation.     

Inflation in the Einstein-Cartan cosmological model

All the three primordial phases of the universe, required by inflation, plus what is believed to be the present phase, have been studied in the Einstein-Cartan cosmological model in a Bianchi type I metric.     

Inflation driven by the Galileon field

We propose a new class of inflation model, G inflation, which has a Galileon-like nonlinear derivative interaction of the form G(?,(??)(2))□? in the Lagrangian with the resultant equations of motion being of second order. It is shown that (almost) scale-invariant curvature fluctuations can be generated even in the exactly de Sitter background and that the tensor-to-scalar ratio can take a significantly larger value than in the standard inflation models, violating the standard consistency relation. Furthermore, violation of the null energy condition can occur without any instabilities. As a result, the spectral index of tensor modes can be blue, which makes it easier to observe quantum gravitational waves from inflation by the planned gravitational-wave experiments such as LISA and DECIGO as well as by the upcoming CMB experiments such as Planck and CMBpol.     

Inflation with superstrings

Cosmological solutions with three exponentially expanding space dimensions in the N=1 supersymmetric Yang-Mills supergravity system are found under the assumption of gluino and “subgravitino” condensation. The potential has a long flat region providing sufficient inflation.     

Inflation Without Potential

Due to the importance of inflation, considerable effort has gone into developingdifferent inflationary scenarios. In most of them inflation is driven by aself-interacting scalar field. Here we discuss an alternative way to implement aninflationary stage provided by noncanonical kinetic terms in the action for thescalar field.     

Inflation,LHC and the Higgs boson

After the Higgs boson has been discovered, the Standard Model of particle physics became a confirmed theory, potentially valid up to the Planck scale and allowing one to trace the evolution of the Universe from the inflationary stage till the present days. We discuss the relation between the results from the LHC and the inflationary cosmology. We overview the Higgs inflation, and its relation to the possible metastability of the electroweak vacuum. A short overview of the bounds on the metastability of the electroweak vacuum in the models with inflation not related to the Higgs boson is presented.     

A One-Dimensional Method for Calculating the Exit Wavefunction

We develop the multi-slice method for calculating wavefunction of a crystal consisting of atomic columns. The new method reduces numerical calculation from two dimensions to one dimension and is much faster than that of the traditional multi-slice method. The calculated result by the one-dimensional method is in agreement with that of the traditional one.     

Baryogenesis in Fresh Inflation

I study the possibility of baryogenesis can take place in fresh inflation. I find that it is possible that violation of baryon number conservation can occur during the period out-of-equilibrium in this scenario. Indeed, baryogenesis could be possible in the range of times (10⁹ – 10¹²) G^1/2, before the thermal equilibrium is restored at the end of fresh inflation.     

Inflation in warped geometries

We argue that brane anti-brane inflation in string theory de-Sitter vacua of Kachru–Kallosh–Linde–Trivedi (KKLT) is captured by the dynamics of a D3-brane probe in the local KKLT model constructed in hep-th/0203041. This provides a framework to study in a controllable way corrections to the inflationary slow roll parameter η due to conformal symmetry breaking in a warped geometry throat. We compute the leading correction to η for the inflation in the Klebanov–Tseytlin throat geometry. We find that in certain regime this correction tends to decrease η. Computations in a different regime suggest however that it is unlikely that η1 can be achieved with the D3-brane throat inflation.