scholarly journals Extended objects in nonperturbative quantum-field theory and the cosmological constant

2017 ◽  
Vol 26 (07) ◽  
pp. 1750074
Author(s):  
Vladimir Dzhunushaliev ◽  
Vladimir Folomeev ◽  
Burkhard Kleihaus ◽  
Jutta Kunz
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Exact Analytical Solution ◽  
Scalar Fields ◽  
Einstein Equations ◽  
Gauge Fields ◽  
Vacuum Fluctuations ◽  
Abelian Gauge ◽  
Extended Object ◽  
Constant Energy Density

We consider a gravitating extended object constructed from vacuum fluctuations of nonperturbatively quantized non-Abelian gauge fields. An approximate description of such an object is given by two gravitating scalar fields. The object has a core filled with a constant energy density of the vacuum fluctuations of the quantum-fields. The core is located inside a cosmological event horizon. An exact analytical solution of the Einstein equations for such a core is presented. The value of the energy density of the vacuum fluctuations is connected with the cosmological constant.

scholarly journals CPTM symmetry, closed time paths and cosmological constant problem in the formalism of extended manifold

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
S. Bondarenko
Keyword(s):  
Cosmological Constant ◽  
Classical Solution ◽  
Vacuum Energy ◽  
Condensed Matter ◽  
Scalar Fields ◽  
Einstein Equations ◽  
Cosmological Constant Problem ◽  
Classical Level ◽  
Extended Space ◽  
Charge Parity

AbstractThe problem of the cosmological constant is considered in the formalism of an extended space-time consisting of the extended classical solution of Einstein equations. The different regions of the extended manifold are proposed to be related by the charge, parity, time and mass (CPTM) reversal symmetry applied with respect to the metric fields of the manifolds. There are interactions between the points of the extended manifold provided by scalar fields present separately in the different patches of the extended solution. The value of the constant is obtained equal to zero at the classical level due the mutual contribution of the fields in the vacuum energy, it’s non-zero value is due the quantum interactions between the fields. There are few possible scenario for the actions of the fields are discussed. Each from the obtained variants is similar to the closed time path approach of non-equilibrium condensed matter physics and among these possibilities for the closed paths, there is a variant of the action equivalent to the formalism of Keldysh. Accordingly, we consider and shortly discuss the application of the proposed formalism to the problem of smallness of the cosmological constant and singularities problem.

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.

MASSLESS SCALAR FIELDS IN NON-ABELIAN KALUZA-KLEIN THEORY

1994 ◽  
Vol 09 (04) ◽  
pp. 507-515 ◽  
Author(s):  
M. ARIK ◽  
V. GABAY
Keyword(s):  
Cosmological Constant ◽  
Direct Product ◽  
Scalar Fields ◽  
Gauge Fields ◽  
Internal Space ◽  
Massless Scalar ◽  
Klein Theory ◽  
Euler Form ◽  
Odd Dimensions ◽  
Kaluza Klein

We investigate the presence of massless scalar fields in a Kaluza—Klein theory based on a dimensionally continued Euler-form action. We show that massless scalar fields exist provided that the internal space is a direct product of two irreducible manifolds. The condition of a vanishing effective four-dimensional cosmological constant and the presence of a graviton, gauge fields and massless scalar fields can be satisfied if both irreducible manifolds have odd dimensions and the sum of these dimensions is equal to the dimension of the Euler form.

scholarly journals MAXWELL SYMMETRIES AND SOME APPLICATIONS

2013 ◽  
Vol 23 ◽  
pp. 350-356 ◽  
Author(s):  
JOSÉ A. DE AZCÁRRAGA ◽  
KIYOSHI KAMIMURA ◽  
JERZY LUKIERSKI
Keyword(s):  
Gauge Theory ◽  
Gravity Field ◽  
Scalar Fields ◽  
Cosmological Term ◽  
Gauge Fields ◽  
Spin Connection ◽  
Field Equations ◽  
Geometric Framework ◽  
Abelian Gauge ◽  
Poincaré Algebra

The Maxwell algebra is the result of enlarging the Poincaré algebra by six additional tensorial Abelian generators that make the fourmomenta non-commutative. We present a local gauge theory based on the Maxwell algebra with vierbein, spin connection and six additional geometric Abelian gauge fields. We apply this geometric framework to the construction of Maxwell gravity, which is described by the Einstein action plus a generalized cosmological term. We mention a Friedman-Robertson-Walker cosmological approximation to the Maxwell gravity field equations, with two scalar fields obtained from the additional gauge fields. Finally, we outline further developments of the Maxwell symmetries framework.

COSMOLOGY WITH NEGATIVE POTENTIALS WITH wϕ<-1

2004 ◽  
Vol 13 (09) ◽  
pp. 1939-1953 ◽  
Author(s):  
A. DE LA MACORRA ◽  
G. GERMÁN
Keyword(s):  
Equation Of State ◽  
Energy Density ◽  
Cosmological Constant ◽  
Particle Physics ◽  
Scalar Potential ◽  
Energy Condition ◽  
State Parameter ◽  
Scalar Fields ◽  
High Energy ◽  
Equation Of State Parameter

We study the cosmology of canonically normalized scalar fields that lead to an equation of state parameter of wϕ=pϕ/ρϕ<-1 without violating the weak energy condition: ρ=Σiρi≥0 and ρi+pi≥0. This kind of behavior requires a negative scalar potential V, widely predicted in particle physics. We show that the energy density ρϕ=Ek+V takes negative values with an equation of state with wϕ<-1. However, the net effect of the ϕ field on the scale factor is to decelerate it giving a total equation of state parameter w=p/ρ>wb=pb/ρb, where ρb stands for any kind of energy density with -1≤wb≤1, such as radiation, matter, cosmological constant or other scalar field with a potential V≥0. The fact that ρϕ<0 allows, at least in principle, to have a small cosmological constant or quintessence today as the cancellation of high energy scales such as the electroweak or susy breaking scale. While V is negative |ρϕ| is smaller than the sum of all other energy densities regardless of the functional form of the potential V. We show that the existence of a negative potential leads, inevitable, to a collapsing universe, i.e. to a would be "big crunch." In this picture we would still be living in the expanding universe.

DIMENSION OF SPACE-TIME IN THIRD QUANTIZED GRAVITY

1989 ◽  
Vol 04 (24) ◽  
pp. 2377-2385 ◽  
Author(s):  
N.G. KOZIMIROV ◽  
I.I. TKACHEV
Keyword(s):  
Cosmological Constant ◽  
Space Time ◽  
Gauge Fields ◽  
Internal Space ◽  
Number Density ◽  
Abelian Gauge

Quantum creation of universes is considered within the framework of linear D-dimensional third quantized gravity with non-abelian gauge fields. It is shown that the number density of universes is infinitely peaked up on a sequence of compactified universes Sn+1×Id, where dimensionality of compact internal space Id takes values d=0, 1, …, D−3 and effective n+1-dimensional cosmological constant tends to zero, Sn+1→Mn+1.

Solitons of Kählerian space-time manifolds

2020 ◽  
pp. 2150021
Author(s):  
M. M. Praveena ◽  
C. S. Bagewadi ◽  
M. R. Krishnamurthy
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Gravitational Constant ◽  
Space Time ◽  
Constant Energy ◽  
Conformal Curvature ◽  
Isotropic Pressure ◽  
Constant Energy Density ◽  
Curvature Tensors

We study solitons of almost pseudo symmetric Kählerian space-time manifold. It is considered that different curvature tensors like projective, conharmonic and conformal curvature tensors in almost pseudo symmetric Kählerian space-time manifolds are flat. It is shown that solitons are steady, expanding or shrinking under different relations of isotropic pressure, the cosmological constant, energy density and gravitational constant..

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