scholarly journals POWER LAW COSMOLOGICAL SOLUTION DERIVED FROM THE DGP BRANE WITH A BRANE TACHYON FIELD

2008 ◽  
Vol 17 (11) ◽  
pp. 2017-2024 ◽  
Author(s):  
YONGLI PING ◽  
LIXIN XU ◽  
HONGYA LIU ◽  
YING SHAO
Keyword(s):  
Power Law ◽  
Cosmological Solution ◽  
Friedmann Equation ◽  
Space Time ◽  
Expanding Universe ◽  
Tachyon Field ◽  
Brane Model

By studying a tachyon field on the DGP brane model, in order to embed the 4D standard Friedmann equation with a brane tachyon field in the 5D bulk, we present the metric of the 5D space–time. Then, adopting the inverse square potential of the tachyon field, we obtain an expanding universe with a power law on the brane and an exact 5D solution.

scholarly journals IMPLEMENTING POWER LAW INFLATION WITH TACHYON ROLLING ON THE BRANE

2003 ◽  
Vol 18 (10) ◽  
pp. 691-697 ◽  
Author(s):  
M. SAMI
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Ground State ◽  
Friedmann Equation ◽  
Brane World ◽  
Tachyon Field

We study a minimally coupled tachyon field rolling down to its ground state on the FRW brane. We construct tachyonic potential which can implement power law inflation in the brane world cosmology. The potential turns out to be V0ϕ-1 on the brane and reduces to inverse square potential at late times when brane corrections to the Friedmann equation become negligible. We also do similar exercise with a normal scalar field and discover that the inverse square potential on the brane leads to power law inflation.

scholarly journals CHAOTIC INFLATION ON THE RANDALL–SUNDRUM TWO-BRANE MODEL

2010 ◽  
Vol 25 (31) ◽  
pp. 2697-2713
Author(s):  
KOUROSH NOZARI ◽  
SIAMAK AKHSHABI
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Friedmann Equation ◽  
Warp Factor ◽  
Model Parameters ◽  
Stabilization Mechanism ◽  
Brane Model ◽  
Inflation Model ◽  
Bulk Scalar Field ◽  
Chaotic Inflation

We construct an inflation model on the Randall–Sundrum I (RSI) brane where a bulk scalar field stabilizes the inter-brane separation. We study impact of the bulk scalar field on the inflationary dynamics on the brane. We proceed in two different approaches: in the first approach, the stabilizing field potential is directly appeared in the Friedmann equation and the resulting scenario is effectively a two-field inflation. In the second approach, the stabilization mechanism is considered in the context of a warp factor so that there is just one field present that plays the roles of both inflaton and stabilizer. We study constraints imposed on the model parameters from recent observations.

scholarly journals SPACE–TIME STRUCTURE AND SPINOR GEOMETRY

2008 ◽  
Vol 50 (2) ◽  
pp. 143-176 ◽  
Author(s):  
GEORGE SZEKERES ◽  
LINDSAY PETERS
Keyword(s):  
Cosmological Solution ◽  
Space Time ◽  
Time Structure ◽  
Variation Principle ◽  
Field Equations ◽  
Covering Group ◽  
Space Time Structure ◽  
Spinor Geometry ◽  
Complete Set ◽  
Particle Solution

AbstractThe structure of space–time is examined by extending the standard Lorentz connection group to its complex covering group, operating on a 16-dimensional “spinor” frame. A Hamiltonian variation principle is used to derive the field equations for the spinor connection. The result is a complete set of field equations which allow the sources of the gravitational and electromagnetic fields, and the intrinsic spin of a particle, to appear as a manifestation of the space–time structure. A cosmological solution and a simple particle solution are examined. Further extensions to the connection group are proposed.

scholarly journals Evolution of a domain wall in expanding universe: inflation and after it

2018 ◽  
Vol 191 ◽  
pp. 08004
Author(s):  
A.D. Dolgov ◽  
S.I. Godunov ◽  
A.S. Rudenko
Keyword(s):  
Domain Wall ◽  
Hubble Parameter ◽  
Domain Walls ◽  
Flat Space ◽  
Space Time ◽  
Time Dependent ◽  
Expanding Universe ◽  
Large Size ◽  
Dependent Parameter ◽  
Thick Domain Walls

We study the evolution of thick domain walls in the expanding universe. We have found that the domain wall evolution crucially depends on the time-dependent parameter C(t) = 1/(H(t)δ0)2, where H(t) is the Hubble parameter and δ0 is the width of the wall in flat space-time. For C(t) > 2 the physical width of the wall, a(t)δ(t), tends with time to constant value δ0, which is microscopically small. Otherwise, when C(t) ≤ 2, the wall steadily expands and can grow up to a cosmologically large size.

scholarly journals QUANTUM SINGULARITIES IN STATIC AND CONFORMALLY STATIC SPACE-TIMES

2011 ◽  
Vol 26 (22) ◽  
pp. 3878-3888 ◽  
Author(s):  
D. A. KONKOWSKI ◽  
T. M. HELLIWELL
Keyword(s):  
Power Law ◽  
Cosmic String ◽  
Higher Order ◽  
Space Time ◽  
Differential Invariants ◽  
Future Research ◽  
Quantum Singularities ◽  
Definition Of ◽  
Friedmann Robertson Walker ◽  
Static Space

The definition of quantum singularity is extended from static space-times to conformally static space-times. After the usual definitions of classical and quantum singularities are reviewed, examples of quantum singularities in static space-times are given. These include asymptotically power-law space-times, space-times with diverging higher-order differential invariants, and a space-time with a 2-sphere singularity. The theory behind quantum singularities in conformally static space-times is followed by an example, a Friedmann-Robertson-Walker space-time with cosmic string. The paper concludes by discussing areas of future research.

scholarly journals Dimensionally Compactified Chern-Simon Theory in 5D as a Gravitation Theory in 4D

2017 ◽  
Vol 45 ◽  
pp. 1760005 ◽  
Author(s):  
Ivan Morales ◽  
Bruno Neves ◽  
Zui Oporto ◽  
Olivier Piguet
Keyword(s):  
Dimensional Space ◽  
Cosmological Solution ◽  
Space Time ◽  
Gravitation Theory ◽  
Simons Theory ◽  
De Sitter ◽  
Field Equations ◽  
Sitter Group ◽  
Dimensional Space Time ◽  
Chern Simons

We propose a gravitation theory in 4 dimensional space-time obtained by compacting to 4 dimensions the five dimensional topological Chern-Simons theory with the gauge group SO(1,5) or SO(2,4) – the de Sitter or anti-de Sitter group of 5-dimensional space-time. In the resulting theory, torsion, which is solution of the field equations as in any gravitation theory in the first order formalism, is not necessarily zero. However, a cosmological solution with zero torsion exists, which reproduces the Lambda-CDM cosmological solution of General Relativity. A realistic solution with spherical symmetry is also obtained.

Space-Time Dynamics of Gazeau-Klauder Coherent States in Power-Law Potentials

2010 ◽  
Vol 49 (10) ◽  
pp. 2540-2557 ◽  
Author(s):  
Shahid Iqbal ◽  
Paula Rivière ◽  
Farhan Saif
Keyword(s):  
Power Law ◽  
Coherent States ◽  
Space Time ◽  
Time Dynamics

scholarly journals D-FOAM PHENOMENOLOGY: DARK ENERGY, THE VELOCITY OF LIGHT AND A POSSIBLE D-VOID

2011 ◽  
Vol 26 (13) ◽  
pp. 2243-2262 ◽  
Author(s):  
JOHN ELLIS ◽  
NICK E. MAVROMATOS ◽  
DIMITRI V. NANOPOULOS
Keyword(s):  
Refractive Index ◽  
Dark Energy ◽  
Energy Density ◽  
Particle Density ◽  
Space Time ◽  
Dark Energy Density ◽  
Present Epoch ◽  
Brane Model ◽  
Velocity Of Light ◽  
Reduced Density

In a D-brane model of cosmology and space–time foam, there are contributions to the dark energy that depend on the D-brane 10-velocities and on the density of D-particle defects in the ten-dimensional bulk. The latter may also reduce the speeds of energetic photons, establishing a phenomenological connection with astrophysical probes of the universality of the velocity of light. Specifically, the cosmological dark energy density measured at the present epoch may be linked to the apparent retardation of energetic photons propagating from nearby AGN's. However, this nascent field of "D-foam phenomenology" may be complicated by variations in the D-particle density encountered at different cosmological epochs. A reduced density of D-particles encountered at redshifts z ~ 1 — a "D-void" — would increase the dark energy while suppressing the vacuum refractive index, and thereby might reconcile the AGN measurements with the relatively small retardation seen for the energetic photons propagating from GRB 090510, as measured by the Fermi satellite.

scholarly journals Circuit Complexity from Cosmological Islands

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1301
Author(s):  
Sayantan Choudhury ◽  
Satyaki Chowdhury ◽  
Nitin Gupta ◽  
Anurag Mishara ◽  
Sachin Panneer Selvam ◽  
...  
Keyword(s):  
Black Hole ◽  
Parameter Space ◽  
Entanglement Entropy ◽  
Cosmological Solution ◽  
Circuit Complexity ◽  
Space Time ◽  
De Sitter ◽  
Squeezed State ◽  
Black Hole Information ◽  
Made In

Recently, in various theoretical works, path-breaking progress has been made in recovering the well-known page curve of an evaporating black hole with quantum extremal islands, proposed to solve the long-standing black hole information loss problem related to the unitarity issue. Motivated by this concept, in this paper, we study cosmological circuit complexity in the presence (or absence) of quantum extremal islands in negative (or positive) cosmological constant with radiation in the background of Friedmann-Lemai^tre-Robertson-Walker (FLRW) space-time, i.e., the presence and absence of islands in anti de Sitter and the de Sitter space-time having SO(2, 3) and SO(1, 4) isometries, respectively. Without using any explicit details of any gravity model, we study the behavior of the circuit complexity function with respect to the dynamical cosmological solution for the scale factors for the above mentioned two situations in FLRW space-time using squeezed state formalism. By studying the cosmological circuit complexity, out-of-time ordered correlators, and entanglement entropy of the modes of the squeezed state, in different parameter space, we conclude the non-universality of these measures. Their remarkably different features in the different parameter space suggests their dependence on the parameters of the model under consideration.

Some properties of the p-brane model with the quadratic lagrangian

1999 ◽  
Vol 4 ◽  
pp. 97-112
Author(s):  
P. Miškinis
Keyword(s):  
Dimensional Space ◽  
Equations Of Motion ◽  
Critical Dimension ◽  
Space Time ◽  
Brane Model ◽  
Arbitrary Topology ◽  
General Properties ◽  
Dimensional Space Time ◽  
Dimensional Surface

Some general properties of the relativistic p-dimensional surface imbedded into D-dimensional space-time and its reduction to the simplest case of the quadratic Lagrangian are considered. The solutions of the equations of motion of such model for the p-brane with arbitrary topology and massless eigenstates, as well as with critical dimension after quantization are presented. Some generalizations for the supermembrane are discussed.

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