Related papers: Problems with Tachyon Inflation
A natural consequence of string theory is a non-commutative structure of space-time on microscopic scales. The existence of a minimal length, and a modification of the effective field theory are two consequences of this space-time…
We discuss the role of torsion in string theory on inducing pseudoscalar degrees of freedom (axions), which in turn couple to (gravitational) Chern-Simons (CS) anomalous terms. Such interactions can induce inflation, of running vacuum type,…
Intersecting D-brane models and their T-dual magnetic compactifications yield attractive models of particle physics where magnetic flux plays a twofold role, being the source of fermion chirality as well as supersymmetry breaking. A…
Decoupling of heavy modes in effective low energy theory is one of the most fundamental concepts in physics. It tells us that modes must have a negligible effect on the physics of gravitational backgrounds with curvature radius larger than…
This is a short account, based on a talk given at the 2024 Moriond Cosmology Conference, of where and why string theory matters in early universe cosmology. It is written for a cosmology audience predisposed to be at best sceptical, and at…
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…
Inflationary models driven by a large number of axion fields are discussed in the context of type IIB compactifications with N=1 supersymmetry. The inflatons arise as the scalar modes of the R-R two-forms evaluated on vanishing two-cycles…
A model of tachyon inflation is proposed in the framework of holographic cosmology. The model is based on a holographic braneworld scenario with a D3-brane located at the holographic boundary of an asymptotic ADS$_5$ bulk. The tachyon field…
In a recent paper we showed how Starobinsky-like inflation could emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane and the effective potential acquires a…
When p-dimensional branes annihilate with antibranes in the early universe, as in brane-antibrane inflation, stable (p-2)-dimensional branes can appear in the final state. We reexamine the possibility that one of these (p-2)-branes could be…
We find a description of hybrid inflation in (3+1)-dimensions using brane dynamics of Hanany-Witten type. P-term inflation/acceleration of the universe with the hybrid potential has a slow-roll de Sitter stage and a waterfall stage which…
We describe string production after angled brane inflation. First, we point out that there was a discrepancy in previous discussions. The expected tension of the cosmic string calculated from the four-dimensional effective Lagrangian did…
I review several aspects of torsion in string-inspired cosmologies. In particular, I discuss its connection with fundamental, string-model independent, axion fields associated with the massless gravitational multiplet of the string. I argue…
We study the problem of scalar particle production after inflation by a rapidly oscillating inflaton field. We use the framework of the chaotic inflation scenario with quartic and quadratic inflaton potentials. Particular attention is paid…
An inflationary stage dominated by a $D$-term avoids the slow-roll problem of inflation in supergravity and may emerge in theories with a non-anomalous or anomalous U(1) gauge symmetry. The most intriguing and commonly invoked possibility…
We develop a numerical statistical method to study linear cosmological fluctuations in inflationary scenarios with multiple fields, and apply it to an ensemble of six-field inflection point models in string theory. The latter are concrete…
These lectures provide an introduction to the subject of tachyon condensation in the open bosonic string. The problem of tachyon condensation is first described in the context of the low-energy Yang-Mills description of a system of multiple…
We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multi-field inflationary models by means of lattice simulations. We observe a strong suppression of resonances in the…
The most important criteria for a successful inflation are to explain the observed temperature anisotropy in the cosmic microwave background radiation, and exiting inflation in a vacuum where it can excite the Standard Model quarks and…
It has recently been realized that brane-antibrane annihilation (a possible explanation for ending inflation) may result in defect formation, due to the dynamics of the tachyon field. Studies of this possibility have generally ignored the…