scholarly journals Cosmological constant, dilaton field and Freund–Rubin compactification

2003 ◽  
Vol 551 (1-2) ◽  
pp. 161-165 ◽  
Author(s):  
Takashi Torii ◽  
Tetsuya Shiromizu
Keyword(s):  
Cosmological Constant ◽  
Dilaton Field ◽  
Constant Dilaton

scholarly journals Minimal surfaces and generalized Einstein–Maxwell-dilaton theory

2019 ◽  
Vol 34 (12) ◽  
pp. 1950061
Author(s):  
M. Butler ◽  
A. M. Ghezelbash
Keyword(s):  
Cosmological Constant ◽  
Physical Properties ◽  
Minimal Surfaces ◽  
Higher Dimensions ◽  
Coupling Constants ◽  
Dilaton Field ◽  
Coupling Constant ◽  
Maxwell Theory ◽  
Five Dimensions ◽  
Cosmological Solutions

We present novel classes of nonstationary solutions to the five-dimensional generalized Einstein–Maxwell-dilaton theory with cosmological constant, in which the Maxwell’s field and the cosmological constant couple to the dilaton field. In the first class of solutions, the two nonzero coupling constants are different, while in the second class of solutions, the two coupling constants are equal to each other. We find consistent cosmological solutions with positive, negative or zero cosmological constant, where the cosmological constant depends on the value of one coupling constant in the theory. Moreover, we discuss the physical properties of the five-dimensional solutions and the uniqueness of the solutions in five dimensions by showing the solutions with different coupling constants cannot be uplifted to any Einstein–Maxwell theory in higher dimensions.

scholarly journals BLACK HOLES IN THE PRESENCE OF COSMOLOGICAL CONSTANT AND LARGE-N BRANE WORLD

2009 ◽  
Vol 24 (26) ◽  
pp. 2107-2118 ◽  
Author(s):  
MINGXING LUO ◽  
SIBO ZHENG
Keyword(s):  
Cosmological Constant ◽  
Higher Dimensions ◽  
Brane World ◽  
Gauge Fields ◽  
Brane Worlds ◽  
Gravitational Theories ◽  
Large N ◽  
Gauge Gravity ◽  
Gravity Duality ◽  
Constant Dilaton

Gravitational theories including negative cosmological constant, dilaton and gauge fields are explored in higher dimensions, in which black hole solutions are shown to exist and their asymptotic behaviors are obtained. Based on these solutions, effective Randall–Sundrum brane worlds are constructed. In the framework of gauge/gravity duality, effects from cosmological constant on the spectra of standard model fields on the branes are perturbatively calculated.

scholarly journals CONSTRAINING THE RUNAWAY DILATON AND QUINTESSENTIAL DARK ENERGY

2010 ◽  
Vol 19 (03) ◽  
pp. 367-394 ◽  
Author(s):  
ISHWAREE P. NEUPANE ◽  
HOLLY TROWLAND
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Cosmological Parameters ◽  
Scalar Fields ◽  
Current Data ◽  
Gravity Models ◽  
Model Parameters ◽  
Dilaton Field ◽  
The Universe

Dark energy is some of the weirdest and most mysterious stuff in the universe that tends to increase the rate of expansion of the universe. Two commonly known forms of dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli whose energy density can vary with time. We explore one particular model for dynamic dark energy: quintessence driven by a scalar dilaton field. We propose an ansatz for the form of the dilaton field, |ϕ(a)|mP ≡ α1 ln t + α2tn = α ln a + βa2ζ, where a is the scale factor and α and ζ are parameters of the model. This phenomenological ansatz for ϕ can be motivated by generic solutions of a scalar dilaton field in many effective string theory and string-inspired gravity models in four dimensions. Most of the earlier discussions in the literature correspond to the choice that ζ = 0 so that ϕ(t) ∝ ln t or ϕ(t) ∝ ln a(t). Using a compilation of current data including type Ia supernovae, we impose observational constraints on the slope parameters like α and ζ and then discuss the relation of our results to analytical constraints on various cosmological parameters, including the dark energy equation of state. Some useful constraints are imposed on model parameters like α and ζ as well as on the dark energy/dark matter couplings using results from structure formation. The constraints of this model are shown to encompass the cosmological constant limit within 1σ error bars.

scholarly journals VANISHING OF THE COSMOLOGICAL CONSTANT, STABILITY OF THE DILATON AND INFLATION

1996 ◽  
Vol 05 (05) ◽  
pp. 567-578
Author(s):  
A. DE LA MACORRA
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Suitable Choice ◽  
Dilaton Field ◽  
String Models ◽  
Large Hierarchy ◽  
Chiral Potential

We study the possibility of canceling the cosmological constant in supergravity string models. We show that with a suitable choice of superpotential the vacuum energy may vanish with the dilaton field at its minimum and supersymmetry broken with a large hierarchy. We derive the condition for which the introduction of a chiral potential, e.g. the inflaton potential, does not destabilize the dilaton field even in the region where the scalar potential takes positive values. This allows for an inflationary potential with the dilaton frozen at its minimum.

scholarly journals Two-dimensional dilaton gravity theory and lattice Schwarzian theory

2019 ◽  
Vol 34 (29) ◽  
pp. 1950176
Author(s):  
Su-Kuan Chu ◽  
Chen-Te Ma ◽  
Chih-Hung Wu
Keyword(s):  
Boundary Condition ◽  
Cosmological Constant ◽  
Dirichlet Boundary Condition ◽  
Dirichlet Boundary ◽  
Gravity Theory ◽  
Boundary Theory ◽  
Two Dimensional ◽  
Dilaton Field ◽  
Dilaton Gravity ◽  
Cosmological Constants

We report a holographic study of a two-dimensional dilaton gravity theory with the Dirichlet boundary condition for the cases of nonvanishing and vanishing cosmological constants. Our result shows that the boundary theory of the two-dimensional dilaton gravity theory with the Dirichlet boundary condition for the case of nonvanishing cosmological constants is the Schwarzian term coupled to a dilaton field, while for the case of vanishing cosmological constant, a theory does not have a kinetic term. We also include the higher derivative term [Formula: see text], where [Formula: see text] is the scalar curvature that is coupled to a dilaton field. We find that the form of the boundary theory is not modified perturbatively. Finally, we show that a lattice holographic picture is realized up to the second-order perturbation of boundary cutoff [Formula: see text] under a constant boundary dilaton field and the nonvanishing cosmological constant by identifying the lattice spacing [Formula: see text] of a lattice Schwarzian theory with the boundary cutoff [Formula: see text] of the two-dimensional dilaton gravity theory.

scholarly journals New class of exact solutions to Einstein–Maxwell-dilaton theory on four-dimensional Bianchi type IX geometry

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Bardia H. Fahim ◽  
Masoud Ghezelbash
Keyword(s):  
Cosmological Constant ◽  
Bianchi Type ◽  
Cosmological Solution ◽  
Constant Term ◽  
Coupling Constants ◽  
Type Ii ◽  
Dilaton Field ◽  
New Class ◽  
Zero Values ◽  
Special Case

AbstractWe construct new classes of cosmological solution to the five dimensional Einstein–Maxwell-dilaton theory, that are non-stationary and almost conformally regular everywhere. The base geometry for the solutions is the four-dimensional Bianchi type IX geometry. In the theory, the dilaton field is coupled to the electromagnetic field and the cosmological constant term, with two different coupling constants. We consider all possible solutions with different values of the coupling constants, where the cosmological constant takes any positive, negative or zero values. In the ansatzes for the metric, dilaton and electromagnetic fields, we consider dependence on time and two spatial directions. We also consider a special case of the Bianchi type IX geometry, in which the geometry reduces to that of Eguchi–Hanson type II geometry and find a more general solution to the theory.

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