CHAOS IN STRING COSMOLOGY

2002 ◽  
Vol 17 (20) ◽  
pp. 2655-2659 ◽  
Author(s):  
THIBAULT DAMOUR
Keyword(s):  
String Theory ◽  
Recent Work ◽  
Coming Out ◽  
String Cosmology ◽  
Low Energy ◽  
Weyl Groups ◽  
Tree Level ◽  
Cosmological Solutions

We briefly review recent work which established the existence of chaos in the generic cosmological solutions of the tree-level low-energy effective actions coming out of string theory, and linked this chaos to the Weyl groups of some hyperbolic Kac-Moody algebras.

scholarly journals STRING COSMOLOGY AND CHAOS

2004 ◽  
Vol 19 (10) ◽  
pp. 1499-1509
Author(s):  
THIBAULT DAMOUR
Keyword(s):  
String Theory ◽  
Coming Out ◽  
String Cosmology ◽  
Low Energy ◽  
Weyl Groups ◽  
Tree Level ◽  
Cosmological Solutions

We briefly review two aspects of string cosmology: (1) the presence of chaos in the generic cosmological solutions of the tree-level low-energy effective actions coming out of string theory, and (2) the remarkable link between the latter chaos and the Weyl groups of some hyperbolic Kac–Moody algebras.

scholarly journals INHOMOGENEOUS STRING COSMOLOGY SOLUTIONS WITH REGULAR SPACE–TIME CURVATURE

1999 ◽  
Vol 14 (01) ◽  
pp. 43-49 ◽  
Author(s):  
LUIS O. PIMENTEL
Keyword(s):  
Effective Action ◽  
Analytic Solutions ◽  
Space Time ◽  
String Cosmology ◽  
Cosmological Models ◽  
Low Energy ◽  
Tree Level ◽  
Regular Space

In this work cosmological models are considered for the low energy string cosmological effective action (tree level) in the absence of dilaton potential. A two-parametric nondiagonal family of analytic solutions is found. The curvature is nonsingular, however the string coupling diverges exponentially.

scholarly journals Extracting bigravity from string theory

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Dieter Lüst ◽  
Chrysoula Markou ◽  
Pouria Mazloumi ◽  
Stephan Stieberger
Keyword(s):  
Scattering Amplitudes ◽  
String Theory ◽  
Open String ◽  
Closed String ◽  
Bimetric Theory ◽  
Low Energy ◽  
Tree Level ◽  
Dark Matter Candidate ◽  
Massive Spin ◽  
Numerical Coefficient

Abstract The origin of the graviton from string theory is well understood: it corresponds to a massless state in closed string spectra, whose low-energy effective action, as extracted from string scattering amplitudes, is that of Einstein-Hilbert. In this work, we explore the possibility of such a string-theoretic emergence of ghost-free bimetric theory, a recently proposed theory that involves two dynamical metrics, that around particular backgrounds propagates the graviton and a massive spin-2 field, which has been argued to be a viable dark matter candidate. By choosing to identify the latter with a massive spin-2 state of open string spectra, we compute tree-level three-point string scattering amplitudes that describe interactions of the massive spin-2 with itself and with the graviton. With the mass of the external legs depending on the string scale, we discover that extracting the corresponding low-energy effective actions in four spacetime dimensions is a subtle but consistent process and proceed to appropriately compare them with bimetric theory. Our findings consist in establishing that string and bimetric theory provide to lowest order the same set of two-derivative terms describing the interactions of the massive spin-2 with itself and with the graviton, albeit up to numerical coefficient discrepancies, a fact that we analyze and interpret. We conclude with a mention of future investigations.

scholarly journals RECONSTRUCTING A STRING-INSPIRED NONMINIMALLY COUPLED QUINTOM MODEL

2009 ◽  
Vol 18 (08) ◽  
pp. 1291-1301 ◽  
Author(s):  
M. R. SETARE ◽  
J. SADEGHI ◽  
A. R. AMANI
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
String Theory ◽  
Scalar Curvature ◽  
Recent Work ◽  
Nonminimal Coupling ◽  
Tachyon Field ◽  
Dynamical Dark Energy

Motivated by the recent work of Zhang and Chen,1we generalize their work to the nonminimally coupled case. We consider a quintom model of dark energy with a single scalar field T given by a Lagrangian inspired by a tachyonic Lagrangian in string theory. We consider nonminimal coupling of the tachyon field to the scalar curvature, and then we reconstruct this model in the light of three forms of parametrization for dynamical dark energy.

scholarly journals GRAVITY ON NONCOMMUTATIVE D-BRANES

2003 ◽  
Vol 18 (07) ◽  
pp. 1051-1066 ◽  
Author(s):  
F. ARDALAN ◽  
H. ARFAEI ◽  
M. R. GAROUSI ◽  
A. GHODSI
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Low Energy ◽  
Bosonic String ◽  
First Order ◽  
Energy Scattering ◽  
Bosonic String Theory ◽  
Brane Action

The effective action for the low energy scattering of two gravitons with a D-brane in the presence of a constant antisymmetric B field in bosonic string theory is calculated and the modification to the standard D-brane action to first order in α′ is obtained.

scholarly journals FROM p-BRANES TO COSMOLOGY

1999 ◽  
Vol 14 (26) ◽  
pp. 4121-4142 ◽  
Author(s):  
H. LÜ ◽  
S. MUKHERJI ◽  
C. N. POPE
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Dimensional Reduction ◽  
Cosmological Models ◽  
Cosmological Solutions ◽  
M Theory ◽  
The Relationship

We study the relationship between static p-brane solitons and cosmological solutions of string theory or M theory. We discuss two different ways in which extremal p-branes can be generalized to nonextremal ones, and show how wide classes of recently discussed cosmological models can be mapped into nonextremal p-brane solutions of one of these two kinds. We also extend previous discussions of cosmological solutions to include some that make use of cosmological-type terms in the effective action that can arise from the generalized dimensional reduction of string theory or M theory.

Some Recent Work in Low Energy X-Ray and Electron Analysis

1969 ◽  
pp. 480-495 ◽  
Author(s):  
Burton L. Henke ◽  
Robert E. Lent
Keyword(s):  
Recent Work ◽  
Low Energy ◽  
X Ray

scholarly journals STRINGS, NONCOMMUTATIVE GEOMETRY AND THE SIZE OF THE TARGET SPACE

1999 ◽  
Vol 14 (28) ◽  
pp. 4501-4517 ◽  
Author(s):  
FEDELE LIZZI
Keyword(s):  
String Theory ◽  
Dirac Operator ◽  
Noncommutative Geometry ◽  
Low Energy ◽  
Target Space ◽  
World Sheet ◽  
Crucial Point ◽  
Spectral Action ◽  
Energy Eigenvalues ◽  
The World

We describe how the presence of the antisymmetric tensor (torsion) on the world sheet action of string theory renders the size of the target space a gauge noninvariant quantity. This generalizes the R ↔ 1/R symmetry in which momenta and windings are exchanged, to the whole O(d,d,ℤ). The crucial point is that, with a transformation, it is possible always to have all of the lowest eigenvalues of the Hamiltonian to be momentum modes. We interpret this in the framework of noncommutative geometry, in which algebras take the place of point spaces, and of the spectral action principle for which the eigenvalues of the Dirac operator are the fundamental objects, out of which the theory is constructed. A quantum observer, in the presence of many low energy eigenvalues of the Dirac operator (and hence of the Hamiltonian) will always interpreted the target space of the string theory as effectively uncompactified.

Projective representations of rotation subgroups of Weyl groups

1987 ◽  
Vol 101 (1) ◽  
pp. 21-35 ◽  
Author(s):  
D. Theo
Keyword(s):  
Recent Work ◽  
Ad Hoc ◽  
Weyl Groups ◽  
Orthogonal Groups ◽  
Central Extensions ◽  
Projective Representations ◽  
Rotation Groups ◽  
Spin Representations ◽  
Double Coverings

By exploiting the well known spin representations of the orthogonal groups O(l), Morris [12] was able to give a unified construction of some of the projective representations of Weyl groups W(Φ) which had previously only been available by ad hoc means [5]. The principal purpose of the present paper is to give a corresponding construction for projective representations of the rotation subgroups W+(Φ) of Weyl groups. Thus we construct non-trivial central extensions of W+(Φ) via the well-known double coverings of the rotation groups SO(l). This adaptation allows us to give a unified way of obtaining the basic projective representations of W+(Φ) from those of W(Φ) determined in [12]. Hence our work is a development of the recent work of Morris, and is an extension of Schur's work on the alternative groups [15].

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