Related papers: Chain Inflation Reconsidered
Previously defined covariant and gauge-invariant perturbation variables, representing, e.g., the fractional spatial energy density gradient on hypersurfaces of constant expansion, are used to simplify the linear perturbation analysis of a…
We analyse the dynamics of spinodal decomposition in inflationary cosmology using the closed time path formalism of out of equilibrium quantum field theory combined with the non-perturbative Hartree approximation. In addition to a general…
We realize and study a model of hybrid inflation in the context of softly broken supersymmetry. The inflaton is taken to be a flat direction in the superfield space and, due to unsuppressed couplings, its soft supersymmetry breaking mass…
We propose a "multi-stream" inflation model, which is a double field model with spontaneous breaking and restoration of an approximate symmetry. We calculate the density perturbation and non-Gaussianity in this model. We find that this…
The spectrum of curvature perturbation generated during inflation is studied in the case the inflation-driving scalar field (inflaton) $\phi$ crosses over its potential extremum. It is shown that the nondecaying mode of perturbation has a…
We study the generation of the primordial curvature perturbation in multi-field inflation. Considering both the evolution of the perturbation during inflation and the effects generated at the end of inflation, we present a general formula…
For hybrid inflationary potentials, we derive the tunneling rate from field configurations along the flat direction towards the waterfall regime. This process competes with the classically rolling evolution of the scalar fields and needs to…
In cascade inflation and some other string inflation models, collisions of mobile branes with other branes or orbifold planes occur and lead to interesting cosmological signatures. The fundamental M/string-theory description of these…
In hybrid inflationary models, inflation ends by a sudden instability associated with a steep ridge in the potential. Here we argue that this feature can generate a large contribution to the curvature perturbation on observable scales. This…
We point out a possible generation mechanism of non-Gaussian bubbles in the sky due to bubble nucleation in the early universe. We consider a curvaton scenario for inflation and assume that the curvaton field phi, whose energy density is…
Multiple axions form a landscape in the presence of various shift symmetry breaking terms. Eternal inflation populates the axion landscape, continuously creating new universes by bubble nucleation. Slow-roll inflation takes place after the…
We consider a multi-field open inflation model, in which one of the fields dominates quantum tunneling from a false vacuum while the other field governs slow-roll inflation within the bubble nucleated from false vacuum decay. We call the…
We present an inflationary universe model which utilizes two coupled real scalar fields. The inflation field $\phi$ experiences a first order phase transition and its potential dominates the energy density of the Universe during the…
We discuss metric perturbations produced during a period of inflation in the early universe where two scalar fields evolve. The final scalar perturbation spectrum can be calculated in terms of the perturbed expansion along neighbouring…
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 investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit.…
There are hidden observables for inflation, such as features localized in position space, which do not manifest themselves when only one inflation trajectory is considered. To address this issue, we investigate inflation dynamics in a…
We consider a variant of hybrid inflation where the waterfall phase transition happens during inflation. By adjusting the parameters associated with the mass of the waterfall field we arrange that the phase transition is not sharp so…
We derive oscillatory signals in correlation functions in two-field open inflation by means of the in-in formalism; such signatures are caused by resonances between oscillations in the tunnelling field and fluctuations in the inflaton…
We show that there exists a simple mechanism which can enhance the amplitude of curvature perturbations on superhorizon scales during inflation, relative to their amplitude at horizon crossing. The enhancement may occur even in a…