scholarly journals SEMICLASSICAL GRAVITATIONAL EFFECTS AROUND GLOBAL MONOPOLE IN BRANS–DICKE THEORY

2008 ◽  
Vol 23 (32) ◽  
pp. 2763-2770 ◽  
Author(s):  
F. RAHAMAN ◽  
P. GHOSH
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Energy Tensor ◽  
Quantum Fields ◽  
Global Monopole ◽  
Stress Energy Tensor ◽  
Gravitational Effects ◽  
Expectation Value ◽  
Stress Energy ◽  
Theory Of Gravity

Recently, W. A. Hiscock4studied the semi classical gravitational effects around global monopole. He obtained the vacuum expectation value of the stress–energy tensor of an arbitrary collection of conformal mass less free quantum fields (scalar, spinor and vectors) in the spacetime of a global monopole. With this stress–energy tensor, we study the semiclassical gravitational effects of a global monopole in the context of Brans–Dicke theory of gravity.

scholarly journals Local zeta regularization and the scalar Casimir effect III. The case with a background harmonic potential

2015 ◽  
Vol 30 (35) ◽  
pp. 1550213 ◽  
Author(s):  
Davide Fermi ◽  
Livio Pizzocchero
Keyword(s):  
Scalar Field ◽  
General Framework ◽  
Casimir Effect ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Harmonic Potential ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Stress Energy

Applying the general framework for local zeta regularization proposed in Part I of this series of papers, we renormalize the vacuum expectation value of the stress-energy tensor (and of the total energy) for a scalar field in presence of an external harmonic potential.

Fermion fields in accelerated states

1978 ◽  
Vol 362 (1709) ◽  
pp. 251-262 ◽  
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Black Body ◽  
Black Body Radiation ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Fermion Fields ◽  
Massless Spin ◽  
Stress Energy

The massless spin-½ and spin-3/2 fields are quantized in the ‘Rindler wedge.’ The vacuum expectation value of the stress-energy tensor is calculated for the spin-½ field and is found to correspond to the absence from the vacuum of black body radiation. Though thermal, the spectrum of the stress tensor has a non-Planckian form.

NON-PERTURBATIVE VACUUM WAVE-FUNCTIONAL AND CLOSED STRING EQUATIONS OF MOTION

1989 ◽  
Vol 04 (10) ◽  
pp. 961-970
Author(s):  
J. GONZÁLEZ
Keyword(s):  
Equations Of Motion ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Closed String ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Stress Energy ◽  
Perturbative Regime ◽  
Variational Condition

The anomalous conformal dependence of the vacuum wave-functional is studied in the non-perturbative regime of the closed bosonic string theory. It is shown that the vanishing of the vacuum expectation value of the stress-energy tensor trace leads to the implementation of a suitable variational condition on the wave-functional, provided that the dilaton condensate be taken as a conformal compensator for the graviton condensate of the embedding space.

scholarly journals Local zeta regularization and the scalar Casimir effect IV: The case of a rectangular box

2016 ◽  
Vol 31 (04n05) ◽  
pp. 1650003 ◽  
Author(s):  
Davide Fermi ◽  
Livio Pizzocchero
Keyword(s):  
Casimir Effect ◽  
Arbitrary Dimension ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Massless Scalar ◽  
Energy Tensor ◽  
Massless Scalar Field ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Stress Energy

Applying the general framework for local zeta regularization proposed in Part I of this series of papers, we compute the renormalized vacuum expectation value of several observables (in particular, of the stress–energy tensor) for a massless scalar field confined within a rectangular box of arbitrary dimension.

Vacuum Stress-Energy Tensor of Nonconformal Scalar Field in Quasi-Euclidean Gravitational Background

1997 ◽  
Vol 06 (04) ◽  
pp. 449-463 ◽  
Author(s):  
M. Bordag ◽  
J. Lindig ◽  
V. M. Mostepanenko ◽  
Yu. V. Pavlov
Keyword(s):  
Scalar Field ◽  
Early Time ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Stress Energy ◽  
The Matrix ◽  
Arbitrary Curvature ◽  
Gravitational Background

The vacuum expectation value of the stress–energy tensor of a quantized scalar field with arbitrary curvature coupling in quasi-Euclidean background is calculated. The early time approximation for nonconformal fields is introduced. This approximation makes it possible to represent the matrix elements of the stress–energy tensor as explicit functionals of the scale factor. In the case of scale factors depending on time by the degree law the energy density is calculated explicitly. It is shown that the new contributions due to nonconformal curvature coupling significantly dominate the previously known conformal contributions.

scholarly journals LIGHT-CONE FLUCTUATIONS AND THE RENORMALIZED STRESS TENSOR OF A MASSLESS SCALAR FIELD

2013 ◽  
Vol 28 (01) ◽  
pp. 1350001 ◽  
Author(s):  
V. A. DE LORENCI ◽  
G. MENEZES ◽  
N. F. SVAITER
Keyword(s):  
Scalar Field ◽  
Light Cone ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Flat Space ◽  
Massless Scalar ◽  
Energy Tensor ◽  
Massless Scalar Field ◽  
Expectation Value ◽  
Stress Energy

We investigate the effects of light-cone fluctuations over the renormalized vacuum expectation value of the stress–energy tensor of a real massless minimally coupled scalar field defined in a (d+1)-dimensional flat space–time with topology [Formula: see text]. For modeling the influence of light-cone fluctuations over the quantum field, we consider a random Klein–Gordon equation. We study the case of centered Gaussian processes. After taking into account all the realizations of the random processes, we present the correction caused by random fluctuations. The averaged renormalized vacuum expectation value of the stress–energy associated with the scalar field is presented.

scholarly journals Massive scalar field theory in the presence of moving mirrors

2018 ◽  
Vol 33 (21) ◽  
pp. 1850126 ◽  
Author(s):  
L. Astrakhantsev ◽  
O. Diatlyk
Keyword(s):  
Canonical Form ◽  
Constant Velocity ◽  
Field Operator ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Commutation Relations ◽  
Conjugate Momentum ◽  
Stress Energy ◽  
Massive Fields

We study the 2D massive fields in the presence of moving mirrors. We do that for standing mirror and mirror moving with constant velocity. We calculate the modes and commutation relations of the field operator with the corresponding conjugate momentum in each case. We find that in case of the ideal mirror, which reflects modes with all momenta equally well, the commutation relations do not have their canonical form. However, in the case of nonideal mirror, which is transparent for the modes with high enough momenta, the commutation relations of the field operator and its conjugate momentum have their canonical form. Then, we calculate the free Hamiltonian and the expectation value of the stress-energy tensor in all the listed situations. In the presence of moving mirrors the diagonal form in terms of the creation and annihilation operators has the operator that performs translations along the mirror’s worldline rather than the one which does translations along the time-line. For the massive fields in the presence of a mirror moving with constant velocity the expectation value of the stress-energy tensor has a nondiagonal contribution which decays with the distance from the mirror.

scholarly journals Mimetic Einstein-Cartan-Sciama-Kibble (ECSK) gravity

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Fernando Izaurieta ◽  
Perla Medina ◽  
Nelson Merino ◽  
Patricio Salgado ◽  
Omar Valdivia
Keyword(s):  
Differential Forms ◽  
Spin Connection ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Total Stress ◽  
Mimetic Theory ◽  
Form Parameter ◽  
First Order ◽  
Stress Energy ◽  
Theory Of Gravity

Abstract In this paper, we formulate the Mimetic theory of gravity in first-order formalism for differential forms, i.e., the mimetic version of Einstein-Cartan-Sciama-Kibble (ECSK) gravity. We consider different possibilities on how torsion is affected by Weyl transformations and discuss how this translates into the interpolation between two different Weyl transformations of the spin connection, parameterized with a zero-form parameter λ. We prove that regardless of the type of transformation one chooses, in this setting torsion remains as a non-propagating field. We also discuss the conservation of the mimetic stress-energy tensor and show that the trace of the total stress-energy tensor is not null but depends on both, the value of λ and spacetime torsion.

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