Related papers: Chain inflation revisited
Does inflation provide a compelling explanation for why the universe is so large, so flat, and so old, and a predictive theory of density perturbations? In this brief contribution (based on the role of the author as moderator of the…
An alternative inflationary model is proposed predicated upon a consideration of the form of the uncertainty principle in a curved background spacetime. An argument is presented suggesting a possible curvature dependence in the correct…
Supersymmetry is the most natural framework for physics above the TeV scale, and the corresponding framework for early-Universe cosmology, including inflation, is supergravity. No-scale supergravity emerges from generic string…
We present a study of open inflation cosmological scenarios in which cosmic strings form betwen the two inflationary epochs. It is shown that in these models strings are stretched outside the horizon due to the inflationary expansion but…
We explore the homogeneous background dynamics and the evolution of generated perturbations of cosmological inflation that is driven by multiple scalar fields interacting with a perfect fluid.Then we apply the method to warm inflation…
In our previous paper, we have proposed a new algorithm to calculate the power spectrum of the curvature perturbations generated in inflationary universe with use of the stochastic approach. Since this algorithm does not need the…
We discuss the challenges of motivating, constructing, and quantizing a canonically normalized inflationary perturbation in spatially curved universes. We show that this has historically proved challenging due to the interaction of…
Starting with a study of the cosmological solution to the Einstein equations for the internal spacetime of an extreme supermassive cosmic string kink, and by evaluating the probability measure for the formation of such a kink in…
We investigate the phenomenology of warm inflation and present generic results about the evolution of the inflaton and radiation fields. The general conditions required for warm inflation to take place are derived and discussed. A…
In this paper we discuss a multi-field model of inflation in which generally all fields are non-minimally coupled to the Ricci scalar and have non-canonical kinetic terms. The background evolution and first-order perturbations for the model…
We propose a stringy version of the old inflation scenario which does not require any slow-roll inflaton potential and is based on a specific example of string compatification with warped metric. Our set-up admits the presence of…
We construct a model of inflation in string theory after carefully taking into account moduli stabilization. The setting is a warped compactification of Type IIB string theory in the presence of D3 and anti-D3-branes. The inflaton is the…
We present a modular cosmology scenario where the difficulties encountered in conventional modular cosmology are solved in a self-consistent manner, with definite predictions to be tested by observation. Notably, the difficulty of the…
Cosmological solutions of the beta function equations for the background fields of the closed bosonic string are investigated at the one-loop level. Following recent work of Kostelecky and Perry, it is assumed that the spatial sections of…
The inflationary scenarios suggested by the duality properties of string cosmology in the Brans-Dicke (or String) frame are shown to correspond to accelerated contraction (deflation) when Weyl-transformed to the Einstein frame. We point out…
I will discuss the development of inflationary theory and its present status, as well as some recent attempts to suggest an alternative to inflation. In particular, I will argue that the ekpyrotic scenario in its original form does not…
In spite of the phenomenological successes of the inflationary universe scenario, the current realizations of inflation making use of scalar fields lead to serious conceptual problems which are reviewed in this lecture. String theory may…
The theory of cosmological perturbations is the main tool which connects theories of the early universe (based on new fundamental physics such as string theory) with cosmological observations. In these lectures, I will provide an…
Following Freivogel {\it et al} we consider inflation in a predictive (or `friendly') region of the landscape of string vacua, as modeled by Arkani-Hamed, Dimopoulos and Kachru. In such a region the dimensionful coefficients of…
This thesis is dedicated to studying cosmological inflation, which is a period of accelerated expansion in the very early Universe that is required to explain the observed anisotropies in the cosmic microwave background. Inflation, when…