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 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.

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 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 A dynamical system analysis of f(R,T) gravity

2016 ◽  
Vol 13 (09) ◽  
pp. 1650108 ◽  
Author(s):  
Behrouz Mirza ◽  
Fatemeh Oboudiat
Keyword(s):  
Dynamical System ◽  
Dynamical Systems ◽  
Equation Of State ◽  
System Analysis ◽  
Equations Of Motion ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Future Singularity ◽  
First Case ◽  
Stress Energy

We investigate equations of motion and future singularities of [Formula: see text] gravity where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of stress-energy tensor. Future singularities for two kinds of equation of state (barotropic perfect fluid and generalized form of equation of state) are studied. While no future singularity is found for the first case, some kind of singularity is found to be possible for the second. We also investigate [Formula: see text] gravity by the method of dynamical systems and obtain some fixed points. Finally, the effect of the Noether symmetry on [Formula: see text] is studied and the consistent form of [Formula: see text] function is found using the symmetry and the conserved charge.

scholarly journals On a viable first-order formulation of relativistic viscous fluids and its applications to cosmology

2017 ◽  
Vol 26 (13) ◽  
pp. 1750146 ◽  
Author(s):  
Marcelo M. Disconzi ◽  
Thomas W. Kephart ◽  
Robert J. Scherrer
Keyword(s):  
Equations Of Motion ◽  
Heavy Ion ◽  
Viscous Fluids ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Relativistic Fluids ◽  
First Order ◽  
Ion Collisions ◽  
Stress Energy ◽  
Barotropic Equation

We consider a first-order formulation of relativistic fluids with bulk viscosity based on a stress-energy tensor introduced by Lichnerowicz. Choosing a barotropic equation-of-state, we show that this theory satisfies basic physical requirements and, under the further assumption of vanishing vorticity, that the equations of motion are causal, both in the case of a fixed background and when the equations are coupled to Einstein's equations. Furthermore, Lichnerowicz's proposal does not fit into the general framework of first-order theories studied by Hiscock and Lindblom, and hence their instability results do not apply. These conclusions apply to the full-fledged nonlinear theory, without any equilibrium or near equilibrium assumptions. Similarities and differences between the approach explored here and other theories of relativistic viscosity, including the Mueller–Israel–Stewart formulation, are addressed. Cosmological models based on the Lichnerowicz stress-energy tensor are studied. As the topic of (relativistic) viscous fluids is also of interest outside the general relativity and cosmology communities, such as, for instance, in applications involving heavy-ion collisions, we make our presentation largely self-contained.

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.

The effect of backreaction on inflationary Brans–Dicke cosmology

2016 ◽  
Vol 25 (10) ◽  
pp. 1650097 ◽  
Author(s):  
M. Sahraee ◽  
M. R. Setare
Keyword(s):  
Energy Momentum Tensor ◽  
Equations Of Motion ◽  
Dimensional Regularization ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Momentum Tensor ◽  
Expectation Values ◽  
Quantum Energy ◽  
Expectation Value ◽  
Dimensional Spacetime

In this paper, we study the effect of the quantum backreaction on Brans–Dicke cosmology in inflation era. We consider an inflaton field in the [Formula: see text]-dimensional spacetime in the framework of Brans–Dicke model. We use a new notation for the Brans–Dicke field in terms of the dilaton field. Then we obtain the vacuum expectation value of the full energy–momentum tensor using WKB approximation of the mode functions which satisfy the equations of motion. The obtained vacuum expectation values of energy–momentum tensor are divergent. In order to renormalize it, we introduce a constant cut-off [Formula: see text]. The vacuum expectation value of energy–momentum tensor is separated to the UV and IR parts by using [Formula: see text] cut-off. Then, we use the dimensional regularization method to eliminate divergences by introducing a counterterm action. Also, we calculate the IR contribution of the vacuum expectation value of energy–momentum tensor. Thus, we obtain a physically finite result for the quantum energy–momentum tensor. Finally, we find the effect of backreaction on scale factor.

Sign in / Sign up

Export Citation Format

Share Document