scholarly journals MULTI-DIMENSIONAL COSMOLOGY AND DSR–GUP

2013 ◽  
Vol 28 (12) ◽  
pp. 1350047 ◽  
Author(s):  
K. ZEYNALI ◽  
F. DARABI ◽  
H. MOTAVALLI
Keyword(s):  
Cosmological Constant ◽  
Generalized Uncertainty Principle ◽  
Internal Space ◽  
Positive Cosmological Constant ◽  
Doubly Special Relativity ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Big Crunch ◽  
The Difference ◽  
Cosmological Constants

A multi-dimensional cosmology with FRW type metric having four-dimensional spacetime and d-dimensional Ricci-flat internal space is considered with a higher-dimensional cosmological constant. The classical cosmology in commutative and Doubly Special Relativity–Generalized Uncertainty Principle (DSR–GUP) contexts is studied and the corresponding exact solutions for negative and positive cosmological constants are obtained. In the positive cosmological constant case, it is shown that unlike the commutative as well as GUP cases, in DSR–GUP case both scale factors of internal and external spaces after accelerating phase will inevitably experience decelerating phase leading simultaneously to a big crunch. This demarcation from GUP originates from the difference between the GUP and DSR–GUP algebras. The important result is that unlike GUP which results in eternal acceleration, DSR–GUP at first generates acceleration but prevents the eternal acceleration at late-times and turns it into deceleration.

scholarly journals HODGE DUALITY AND COSMOLOGICAL CONSTANT

2006 ◽  
Vol 21 (02) ◽  
pp. 127-141 ◽  
Author(s):  
HITOSHI NISHINO ◽  
SUBHASH RAJPOOT
Keyword(s):  
Field Strength ◽  
Cosmological Constant ◽  
Classical Level ◽  
Simple Mechanism ◽  
Dimensional Spacetime ◽  
Form Field ◽  
Supersymmetric Theories ◽  
Chern Simons ◽  
Cosmological Constants ◽  
Field Strengths

We present a simple mechanism to eliminate cosmological constants both in supersymmetric and non-supersymmetric theories. This mechanism is based on the Hodge (Poincaré) duality between a 0-form and D-form field strengths in D-dimensional spacetime. The new key ingredient is the introduction of an extra Chern–Simons term into the D-form field strength H dual to the 0-form field strength. Our formulation can also be made consistent with supersymmetry. Typical applications to four-dimensional N = 1 supergravity and to ten-dimensional type IIA supergravity are given. The success of our formulation for both supersymmetric and non-supersymmetric systems strongly indicates the validity of our mechanism even after supersymmetry breakings at the classical level. Our mechanism may well be applicable to quantized systems, at least for supersymmetric cases with fundamental D-brane actions available.

scholarly journals COSMOLOGICAL CONSTANT, GENERATION OF DIMENSIONS AND THE EFFECTS OF ANISOTROPY IN MULTIDIMENSIONAL SPACETIME

2012 ◽  
Vol 27 (15) ◽  
pp. 1250088
Author(s):  
SERGEY V. YAKOVLEV
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Effective Mass ◽  
Vacuum Energy ◽  
Initial Conditions ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Dimensional Spacetime ◽  
Higher Dimensional

In the paper, multidimensional anisotropic metric and density of vacuum energy in the Kasner's model are investigated. It is shown that the presence of scalar field in model is equivalent to metric in the spacetime with additional dimensions and we propose the idea of generating additional dimensions by massless scalar field. We propose a method of renormalization of metric that describes conversion from spacetime with scalar field to higher-dimensional spacetime. We obtain the expression for cosmological constant which depends on the initial conditions for anisotropic metric coefficients. Using the method of Bogolubov, we investigate the influence of anisotropic metric onto the cosmological birth of particles and obtain the effective mass of scalar field depending on the cosmological constant.

scholarly journals Neutral signature gauged supergravity solutions

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
J. Gutowski ◽  
W. A. Sabra
Keyword(s):  
Cosmological Constant ◽  
Geometric Structure ◽  
Base Space ◽  
Killing Spinor ◽  
Positive Cosmological Constant ◽  
3 Dimensional

Abstract We classify all supersymmetric solutions of minimal D = 4 gauged supergravity with (2) signature and a positive cosmological constant which admit exactly one Killing spinor. This classification produces a geometric structure which is more general than that found for previous classifications of N = 2 supersymmetric solutions of this theory. We illustrate how the N = 2 solutions which consist of a fibration over a 3-dimensional Lorentzian Gauduchon-Tod base space can be written in terms of this more generic geometric structure.

scholarly journals Relationship between Bondi–Sachs quantities and source of gravitational radiation in asymptotically de Sitter spacetime

2018 ◽  
Vol 27 (04) ◽  
pp. 1850046 ◽  
Author(s):  
Xiaokai He ◽  
Jiliang Jing ◽  
Zhoujian Cao
Keyword(s):  
Cosmological Constant ◽  
Gravitational Wave ◽  
Gravitational Radiation ◽  
The Other ◽  
Perturbation Approach ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Sitter Spacetime ◽  
Explicit Expressions

Gravitational radiation plays an important role in astrophysics. Based on the fact that our universe is expanding, the gravitational radiation when a positive cosmological constant is presented has been studied along with two different ways recently, one is the Bondi–Sachs (BS) framework in which the result is shown by BS quantities in the asymptotic null structure, the other is the perturbation approach in which the result is presented by the quadrupoles of source. Therefore, it is worth to interpret the quantities in asymptotic null structure in terms of the information of the source. In this paper, we investigate this problem and find the explicit expressions of BS quantities in terms of the quadrupoles of source in asymptotically de Sitter spacetime. We also estimate how far away the source is, the cosmological constant may affect the detection of the gravitational wave.

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