scholarly journals Analytic approximation and an improved method for computing the stress-energy of quantized scalar fields in Robertson-Walker spacetimes

1999 ◽  
Vol 61 (2) ◽  
Author(s):  
Paul R. Anderson ◽  
Wayne Eaker
Keyword(s):  
Scalar Fields ◽  
Analytic Approximation ◽  
Improved Method ◽  
Stress Energy

scholarly journals A transition between bouncing hyper-inflation to ΛCDM from diffusive scalar fields

2018 ◽  
Vol 33 (20) ◽  
pp. 1850119 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Numerical Solutions ◽  
Diffusion Constant ◽  
Scalar Fields ◽  
Big Bang ◽  
Energy Tensor ◽  
Stress Energy ◽  
Two Measures ◽  
The Universe

We consider the history of the universe from a possible big bang or a bounce into a late period of a unified interacting dark energy–dark matter model. The model is based on the Two Measures Theories (TMT) which introduces a metric independent volume element and this allows us to construct a unification of dark energy and dark matter. A generalization of the Two Measures Theories gives a diffusive nonconservative stress-energy–momentum tensor in addition to the conserved stress-energy tensor which appear in Einstein equations. These leads to a formulation of interacting DE–DM dust models in the form of a diffusive-type interacting Unified Dark Energy and Dark Matter scenario. The deviation from [Formula: see text]CDM is determined by the diffusion constant [Formula: see text]. For [Formula: see text] the model is indistinguishable from [Formula: see text]CDM. Numerical solutions of the theories show that in some [Formula: see text] the evolution of the early universe is governed by Stiff equation of state or the universe bounces to hyper-inflation. But all of those solutions have a final transition to [Formula: see text]CDM as a stable fixed point for the late universe.

2D BLACK HOLES AND DIMENSIONAL REDUCTION

2002 ◽  
Vol 17 (20) ◽  
pp. 2745-2745
Author(s):  
R. BALBINOT ◽  
A. FABBRI
Keyword(s):  
Black Holes ◽  
Effective Action ◽  
Canonical Quantization ◽  
Scalar Fields ◽  
Mathematical Treatment ◽  
Energy Tensor ◽  
Asymptotic Results ◽  
Stress Energy ◽  
Point Splitting ◽  
Quantum Stress Tensor

The use of lower-dimensional models is exploited in many areas of physics as a way to simplify the mathematical treatment of very complicated phenomena while, at the same time, retaining the main physical ingredients. For the case of black holes, the Hawking evaporation process1 can be understood using a simple model where the gravity action is coupled to quantized matter in the form of free two-dimensional minimal scalar fields. In particular, the effective action one derives by straightforward integration of the trace anomaly2 gives a stress energy tensor which in the Schwarzschild spacetime perfectly agrees with the results one gets by standard canonical quantization. Trying to improve the model, i.e. by employing a spherically reduced 4d minimal scalar field3, one faces a number of difficulties. Unphysical results obtained for the evaporation of black holes (such as antievaporation3,4) using the anomaly induced effective action led us to perform a rigorous calculation of the quantum stress tensor in Schwarzschild by using the point-splitting regularization technique5: exact asymptotic results close to the horizon and at infinity have been derived in the three quantum states of interest (namely Boulware, Hartle-Hawking and Unruh) and two analytic approximations proposed , one valid for large r (based on the WKB) and the other being physically meaningful in the region close to the horizon. Finally, based on these results a "phenomenological" modification of the (unsatisfactory) anomaly induced effective action has been carried out6.

Stress-energy tensor of quantized scalar fields in static spherically symmetric spacetimes

1995 ◽  
Vol 51 (8) ◽  
pp. 4337-4358 ◽  
Author(s):  
Paul R. Anderson ◽  
William A. Hiscock ◽  
David A. Samuel
Keyword(s):  
Scalar Fields ◽  
Energy Tensor ◽  
Spherically Symmetric ◽  
Stress Energy Tensor ◽  
Symmetric Spacetimes ◽  
Stress Energy ◽  
Spherically Symmetric Spacetimes ◽  
Static Spherically Symmetric Spacetimes

STRING THEORIES ON RIEMANN SURFACES OF ALGEBRAIC FUNCTIONS

1990 ◽  
Vol 05 (14) ◽  
pp. 2799-2820 ◽  
Author(s):  
FRANCO FERRARI
Keyword(s):  
Abelian Group ◽  
Riemann Surface ◽  
Riemann Surfaces ◽  
Scalar Fields ◽  
Conformal Weight ◽  
Energy Tensor ◽  
Branch Points ◽  
Stress Energy Tensor ◽  
Tensor Method ◽  
Stress Energy

In this paper we extend to a general Riemann surface a formalism used so far for surfaces with Abelian group of symmetry. Using an algebraic equation F(z, w)=0 to define the surface in terms of sheets and branch points, it is possible to construct the correlation functions for b—c systems with integer conformal weight j and for the scalar fields X. Explicit examples are provided for a general surface of genus three and a surface of genus four. No essential complication arises with respect to the hyperelliptic case. At the end we discuss the computation of chiral determinants det [Formula: see text] using the stress energy tensor method.

scholarly journals $$T\bar{T}$$ deformation of chiral bosons and Chern–Simons $$\hbox {AdS}_3$$ gravity

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Hao Ouyang ◽  
Hongfei Shu
Keyword(s):  
Black Hole ◽  
Scalar Fields ◽  
Flow Equation ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Btz Black Hole ◽  
Stress Energy ◽  
The One ◽  
Chiral Bosons ◽  
Chern Simons

AbstractWe study the $$T\bar{T}$$ T T ¯ deformation of the chiral bosons and show the equivalence between the chiral bosons of opposite chiralities and the scalar fields at the Hamiltonian level under the deformation. We also derive the deformed Lagrangian of more generic theories which contain an arbitrary number of chiral bosons to all orders. By using these results, we derive the $$T\bar{T}$$ T T ¯ deformed boundary action of the $$\hbox {AdS}_3$$ AdS 3 gravity theory in the Chern–Simons formulation. We compute the deformed one-loop torus partition function, which satisfies the $$T\bar{T}$$ T T ¯ flow equation up to the one-loop order. Finally, we calculate the deformed stress–energy tensor of a solution describing a BTZ black hole in the boundary theory, which coincides with the boundary stress–energy tensor derived from the BTZ black hole with a finite cutoff.

The stress-energy tensor

2019 ◽  
pp. 59-65
Author(s):  
Steven Carlip
Keyword(s):  
Equations Of Motion ◽  
Scalar Fields ◽  
Gravitational Energy ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Field Equations ◽  
Perfect Fluids ◽  
Stress Energy ◽  
Relationship Of ◽  
The Relationship

The “source” of gravity in the Einstein field equations is the stress-energy tensor. After a discussion of why gravitational mass should be part of a rank two tensor, this chapter derives the stress-energy tensor for a variety of types of matter: point particles, perfect fluids, scalar fields, and electromagnetism. The chapter discusses the relationship of differential and integral conservation laws, and introduces the problem of gravitational energy. It concludes with a discussion of one of the most remarkable results of general relativity, the fact that equations of motion for matter do not need to be introduced separately, but follow from the field equations.

Stress-energy tensor of quantized scalar fields in static black hole spacetimes

1993 ◽  
Vol 70 (12) ◽  
pp. 1739-1742 ◽  
Author(s):  
Paul R. Anderson ◽  
William A. Hiscock ◽  
David A. Samuel
Keyword(s):  
Black Hole ◽  
Scalar Fields ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Black Hole Spacetimes ◽  
Static Black Hole ◽  
Stress Energy

An Improved Method for the Preparation and TEM Examination of Sharp Pointed Tips used in APFIM and STM

1990 ◽  
Vol 48 (2) ◽  
pp. 102-103
Author(s):  
E.A. Fischione ◽  
P.E. Fischione ◽  
J.J. Haugh ◽  
M.G. Burke
Keyword(s):  
Atom Probe ◽  
Preparation Process ◽  
Improved Method ◽  
Ion Milling ◽  
Polishing Process ◽  
Probe Field ◽  
Scanning Tunnelling ◽  
Stm Tips ◽  
Tunnelling Microscopy ◽  
Ion Microscopy

A common requirement for both Atom Probe Field-Ion Microscopy (APFIM) and Scanning Tunnelling Microscopy (STM) is a sharp pointed tip for use as either the specimen (APFIM) or the probe (STM). Traditionally, tips have been prepared by either chemical or electropolishing techniques. Recently, ion-milling has been successfully employed in the production of APFIM tips [1]. Conventional electropolishing techniques are applicable to a wide variety of metals, but generally require careful manual adjustments during the polishing process and may also be time-consuming. In order to reduce the time and effort involved in the preparation process, a compact, self-contained polishing unit has been developed. This system is based upon the conventional two-stage electropolishing technique in which the specimen/tip blank is first locally thinned or “necked”, and subsequently electropolished until separation occurs.[2,3] The result of this process is the production of two APFIM or STM tips. A mechanized polishing unit that provides these functions while automatically maintaining alignment has been designed and developed.

Immunoelectron microscopic localization of elastic tissue in archival material using an improved method

1990 ◽  
Vol 48 (3) ◽  
pp. 794-795
Author(s):  
J. C. Fanning ◽  
J. F. White ◽  
R. Polewski ◽  
E. G. Cleary
Keyword(s):  
Normal Animal ◽  
Animal Tissue ◽  
Elastic Tissue ◽  
Human Tissues ◽  
Improved Method ◽  
Tissue Samples ◽  
Archival Material ◽  
Immuno Electron Microscopy ◽  
Arteries And Veins ◽  
Biochemical Examination

Elastic tissue is an important component of the walls of arteries and veins, of skin, of the lungs and in lesser amounts, of many other tissues. It is responsible for the rubber-like properties of the arteries and for the normal texture of young skin. It undergoes changes in a number of important diseases such as atherosclerosis and emphysema and on exposure of skin to sunlight.We have recently described methods for the localizationof elastic tissue components in normal animal and human tissues. In the study of developing and diseased tissues it is often not possible to obtain samples which have been optimally prepared for immuno-electron microscopy. Sometimes there is also a need to examine retrospectively samples collected some years previously. We have therefore developed modifications to our published methods to allow examination of human and animal tissue samples obtained at surgery or during post mortem which have subsequently been: 1. stored frozen at -35° or -70°C for biochemical examination; 2.

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