scholarly journals Finite-temperature scalar fields and the cosmological constant in an Einstein universe

2003 ◽  
Vol 67 (4) ◽  
Author(s):  
M. B. Altaie ◽  
M. R. Setare
Keyword(s):  
Cosmological Constant ◽  
Finite Temperature ◽  
Scalar Fields ◽  
Einstein Universe ◽  
Temperature Scalar

scholarly journals A simple assessment on the hierarchy problem

2016 ◽  
Vol 13 (06) ◽  
pp. 1650068 ◽  
Author(s):  
Luca Fabbri
Keyword(s):  
Standard Model ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Hierarchy Problem ◽  
Cosmological Constant Problem ◽  
The Standard Model

We consider the simplest extension of the standard model, where torsion couples to spinor as well as the scalar fields, and in which the cosmological constant problem is solved.

SCHWINGER α-PARAMETRIC REPRESENTATION OF FINITE TEMPERATURE FIELD THEORIES: RENORMALIZATION

1990 ◽  
Vol 05 (23) ◽  
pp. 4427-4440 ◽  
Author(s):  
M. BENHAMOU ◽  
A. KASSOU-OU-ALI
Keyword(s):  
Temperature Field ◽  
Scalar Field ◽  
Finite Temperature ◽  
Short Range ◽  
Parametric Representation ◽  
Field Theories ◽  
Compact Form ◽  
Zero Temperature ◽  
Feynman Amplitudes ◽  
Temperature Scalar

We present the extension of the zero temperature Schwinger α-representation to the finite temperature scalar field theories. We give, in a compact form, the α-integrand of Feynman amplitudes of these theories. Using this representation, we analyze short-range divergences, and recover in a simple way the known result that the counterterms are temperature-independent.

FINITE TEMPERATURE EFFECTIVE POTENTIAL IN A KALUZA-KLEIN UNIVERSE

1990 ◽  
Vol 05 (02) ◽  
pp. 353-361 ◽  
Author(s):  
PINAKI ROY
Keyword(s):  
Low Temperature ◽  
Effective Potential ◽  
Finite Temperature ◽  
Scalar Fields ◽  
Walker Metric ◽  
The One ◽  
Kaluza Klein

We evaluate the finite temperature one-loop effective potential for scalar fields in Kaluza-Klein universe consisting of the product of a space with open Robertson-Walker metric and the N sphere SN. The one-loop effective potential has been computed in both high and low temperature limits.

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.

scholarly journals SPHERICALLY SYMMETRIC MASSIVE SCALAR FIELDS IN GENERAL RELATIVITY

2010 ◽  
Vol 25 (07) ◽  
pp. 1429-1438 ◽  
Author(s):  
MOHAMMAD MEHRPOOYA ◽  
D. MOMENI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Matter Field ◽  
Massless Scalar ◽  
Special Choice ◽  
Spherically Symmetric ◽  
Elementary Functions ◽  
Field Equations ◽  
Tidal Forces

First, we review some attempts made to find the exact spherically symmetric solutions to Einstein field equations in the presence of scalar fields. Wyman's solution in both the static and the nonstatic scalar field is discussed, and it is shown why in the case of the nonstatic homogenous matter field the static metric cannot be represented in terms of elementary functions. We mention here that if the space–time is static, according to field equations, there are two options for fixing the scalar field: static (time-independent) and nonstatic (time-dependent). All these solutions are limited to the minimally coupled massless scalar fields and also in the absence of the cosmological constant. Then we show that if we are interested to have homogenous isotropic scalar field matter, we can construct a series solution in terms of the scalar field's mass and cosmological constant. This solution is static and possesses a locally flat case as a special choice of the mass of the scalar field and can be interpreted as an effective vacuum. Therefore, the mass of the scalar field eliminates any locally gravitational effect as tidal forces. Finally, we describe why this system is unstable in the language of dynamical systems.

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