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About 3,004 papers for “String cosmology”

String cosmology

S Cotsakis · Research Portal (King's College London) · 2002

'Old' String Theory is a theory of one-dimensional extended objects, whose vibrations correspond to excitations of various target-space field modes including gravity. It is for this reason that, strings present, the first, up to now, mathematically consistent framework where quantum gravity is unified with the rest of the fundamental interactions in nature. In these lectures I will give an introduction to low-energy Effective Target-Space Actions derived from conformal invariance conditions of the underlying sigma models in string theory. In this context, I shall discuss cosmology, emphasizing the role of the dilaton field in inducing inflationary scenaria and in general expanding string universes. Specifically, I shall analyse some exact solutions of string theory with a linear dilaton, and discuss their role in inducing expanding Robertson-Walker Universes. I will mention briefly pre-Big-Bang scenaria of String Cosmology, in which the dilaton plays a crucial role. In view of recent claims on experimental evidence (from diverse astrophysical sources) on the existence of cosmic acceleration in the universe today, with a positive non-zero cosmological constant, (de Sitter type), I shall also discuss difficulties of incorporating such Universes with eternal acceleration in the context of critical string theory, and present scenaria for a graceful exit from such a phase.

Cited by 0

String cosmology

N E Mavromatos · Research Portal (King's College London) · 2002

Cited by 0

String cosmology

James M. Cline · 2013

1.1. The problem of scales 5 1.2. The string theory landscape 6 1.3. The Bousso-Polchinski (Brown-Teitelboim) mechanism 9

Cited by 0

String Cosmology

Mavromatos, Nikolaos E · CERN Bulletin · 2001

`Old' String Theory is a theory of one-dimensional extended objects, whose vibrations correspond to excitations of various target-space field modes including gravity. In these lectures I will give an introduction to low-energy Effective Target-Space Actions derived from conformal invariance conditions of the underlying sigma models in string theory, discuss cosmology, emphasizing the role of the dilaton field in inducing inflationary scenaria and in general expanding string universes. Specifically, I shall analyse some exact solutions of string theory with a linear dilaton, and discuss their role in inducing expanding Robertson-Walker Universes. I will mention briefly pre-Big-Bang scenaria of String Cosmology, in which the dilaton plays a crucial role. In view of recent claims on experimental evidence on the existence of cosmic acceleration in the universe today, with a positive non-zero cosmological constant (de Sitter type), I shall also discuss difficulties of incorporating such Universes with eternal acceleration in the context of critical string theory, and present scenaria for a graceful exit from such a phase.

Cited by 0

String Cosmology

A. A. Coley · Astrophysics and space science library · 2003

Cited by 1

STRING COSMOLOGY

Angelantonj, C., Litterio, M. · Institutional Research Information System University of Turin (University of Turin) · 1994

Cited by 0Open access

String cosmology

Lukas, A · Oxford University Research Archive (ORA) (University of Oxford) · 2005

Cited by 0

String Cosmology

Copeland, E J · CERN Bulletin · 2002

We present a brief review of recent advances in string cosmology. Starting with the Dilaton-Moduli Cosmology (known also as the Pre Big Bang), we go on to include the effects of axion fields and address the thorny issue of the Graceful Exit in String Cosmology. This is followed by a review of density perturbations arising in string cosmology and we finish with a brief introduction to the impact moving five branes can have on the Dilaton-Moduli cosmological solutions.

Cited by 0

String cosmology

John D. Barrow, Kerstin E. Kunze, Astronomy Centre · 2013

An overview is given of the formulation of low-energy string cosmologies together with examples of particular solutions, successes and problems of the theory. 1

Cited by 0

String cosmology

Jnanadeva Maharana, Sudipta Mukherji · Pramana · 1999

Cited by 0

String cosmology

James M. Cline · 2013

1.1. The problem of scales 5 1.2. The string theory landscape 6 1.3. The Bousso-Polchinski (Brown-Teitelboim) mechanism 9

Cited by 0

String Cosmology

Cline, J M · CERN Bulletin · 2006

A pedagogical introduction to aspects of string cosmology, including the landscape (BPBT) solution to the cosmological constant problem, brane-antibrane inflation, warped compactification, the KKLMMT model, the eta problem of SUGRA models, DBI inflation, Kahler modulus and racetrack inflation, the D3-D7 model, cosmic superstrings, and the problem of reheating. Also includes basic methods for phenomenology of multifield models with nonstandard kinetic terms.

Cited by 0

String Cosmology

Lorenzo Cornalba, Miguel S. Costa · 2003

Abstract: In these lectures, we review the physics of time–dependent orbifolds of string theory, with particular attention to orbifolds of three–dimensional Minkowski space. We discuss the propagation of free particles in the orbifold geometries, together with their interactions. We address the issue of stability of these string vacua and the difficulties in defining a consistent perturbation theory, pointing to possible solutions. In particular, it is shown that resumming part of the perturbative expansion gives finite amplitudes. Finally we discuss the duality of some orbifold models with the physics of orientifold planes, and we describe cosmological models based on the dynamics of these orientifolds. 1 Updated version of lectures by M.S. Costa at RTN Winter School on Strings, Supergravity and Gauge Theory (Torino, A fundamental problem of theoretical physics is concerned with the nature of the initial cosmological singularity. General relativity, which describes the universe at large scales [1], predicts that, under generic assumptions, the universe went through a phase of high curvature, where quantum gravity should have been important. Hence, the reasons behind

Cited by 0

String Gas Cosmology

Watson, Scott, Battefeld, Thorsten · 2006

We present a critical review and summary of String Gas Cosmology. We include a pedagogical derivation of the effective action starting from string theory, emphasizing the necessary approximations that must be invoked. Working in the effective theory, we demonstrate that at late-times it is not possible to stabilize the extra dimensions by a gas of massive string winding modes. We then consider additional string gases that contain so-called enhanced symmetry states. These string gases are very heavy initially, but drive the moduli to locations that minimize the energy and pressure of the gas. We consider both classical and quantum gas dynamics, where in the former the validity of the theory is questionable and some fine-tuning is required, but in the latter we find a consistent and promising stabilization mechanism that is valid at late-times. In addition, we find that string gases provide a framework to explore dark matter, presenting alternatives to \LambdaCDM as recently considered by Gubser and Peebles. We also discuss quantum trapping with string gases as a method for including dynamics on the string landscape.

Cited by 0Open access

String Cosmology Slides

Zachary Kenton · Figshare · 2014

Talk given 04/06/14 on "String Cosmology."<br>Part of the PhD Student Seminars, Queen Mary University of London.

Cited by 0Open access

String Cosmology Slides

Zachary Kenton · Figshare · 2014

Talk given 04/06/14 on "String Cosmology."<br>Part of the PhD Student Seminars, Queen Mary University of London.

Cited by 0Open access