Wightman function and Casimir densities for Robin plates in the Fulling-Rindler vacuum

Wightman function, the vacuum expectation values of the field square and the energy-momentum tensor are investigated for a massive scalar field with an arbitrary curvature coupling parameter in the region between two infinite parallel plates moving by uniform proper acceleration. We assume that the field is prepared in the Fulling-Rindler vacuum state and satisfies Robin boundary conditions on the plates. The mode-summation method is used with a combination of a variant of the generalized Abel-Plana formula. This allows to extract manifestly the contributions to the expectation values due to a single boundary and to present the second plate-induced parts in terms of exponentially convergent integrals. Various limiting cases are investigated. The vacuum forces acting on the boundaries are presented as a sum of the self-action and 'interaction' terms. The first one contains well known surface divergences and needs a further renormalization. The 'interaction' forces between the plates are investigated as functions of the proper accelerations and coefficients in the boundary conditions. We show that there is a region in the space of these parameters in which the 'interaction' forces are repulsive for small distances and attractive for large distances.Comment: 20 pages, 2 figures, discussion added, accepted for publication in Int. J. Mod. Phys.

Vacuum Quantum Effects for Parallel Plates Moving by Uniform Acceleration in Static de Sitter Space

The Casimir forces on two parallel plates moving by uniform proper acceleration in static de Sitter background due to conformally coupled massless scalar field satisfying Dirichlet boundary conditions on the plates is investigated. Static de Sitter space is conformally related to the Rindler space, as a result we can obtain vacuum expectation values of energy-momentum tensor for conformally invariant field in static de Sitter space from the corresponding Rindler counterpart by the conformal transformation.Comment: 10 pages, no figures, accepted for publication in Int. J. Mod. Phys.

On the energy-momentum tensor for a scalar field on manifolds with boundaries

We argue that already at classical level the energy-momentum tensor for a scalar field on manifolds with boundaries in addition to the bulk part contains a contribution located on the boundary. Using the standard variational procedure for the action with the boundary term, the expression for the surface energy-momentum tensor is derived for arbitrary bulk and boundary geometries. Integral conservation laws are investigated. The corresponding conserved charges are constructed and their relation to the proper densities is discussed. Further we study the vacuum expectation value of the energy-momentum tensor in the corresponding quantum field theory. It is shown that the surface term in the energy-momentum tensor is essential to obtain the equality between the vacuum energy, evaluated as the sum of the zero-point energies for each normal mode of frequency, and the energy derived by the integration of the corresponding vacuum energy density. As an application, by using the zeta function technique, we evaluate the surface energy for a quantum scalar field confined inside a spherical shell.Comment: 25 pages, 2 figures, section and appendix on the surface energy for a spherical shell are added, references added, accepted for publication in Phys. Rev.

Casimir energy in the Fulling--Rindler vacuum

The Casimir energy is evaluated for massless scalar fields under Dirichlet or Neumann boundary conditions, and for the electromagnetic field with perfect conductor boundary conditions on one and two infinite parallel plates moving by uniform proper acceleration through the Fulling--Rindler vacuum in an arbitrary number of spacetime dimension. For the geometry of a single plate the both regions of the right Rindler wedge, (i) on the right (RR region) and (ii) on the left (RL region) of the plate are considered. The zeta function technique is used, in combination with contour integral representations. The Casimir energies for separate RR and RL regions contain pole and finite contributions. For an infinitely thin plate taking RR and RL regions together, in odd spatial dimensions the pole parts cancel and the Casimir energy for the whole Rindler wedge is finite. In $d=3$ spatial dimensions the total Casimir energy for a single plate is negative for Dirichlet scalar and positive for Neumann scalar and the electromagnetic field. The total Casimir energy for two plates geometry is presented in the form of a sum of the Casimir energies for separate plates plus an additional interference term. The latter is negative for all values of the plates separation for both Dirichlet and Neumann scalars, and for the electromagnetic field.Comment: 28 pages, 4 figures, references added, typos corrected, accepted for publication in Phys. Rev.

Accelerated Expansion of the Early and Late Universe in Terms of the Scalar-Tensor Theory of Gravitation. I

© 2017 Springer Science+Business Media New YorkThe basic idea behind the evolutionary development of the early universe is that the hot stage was preceded by the inflationary stage. In most modern concepts of the inflationary regime, it is assumed that a specific scalar field (inflaton) is present which expands space at enormous rates, while the temperature falls rapidly, real particles almost vanish, and the universe is filled by a vacuum with the equation of state P = – ɛ. In the first part of this article, the cosmological scalar of the modified Jordan-Brans-Dicke (JBD) theory is chosen to be the inflaton. Problems in the “Einstein” and proper representations of the JBD theory are considered

Some Properties of Stationary Gravitational Fields

© 2015 Springer Science+Business Media New York The problem of stationary gravitational fields is still far from solved, since there is no exact general solution of the Einstein equations for stationary gravitational fields. This paper examines an approach to this problem employing isotropic coordinates which, in particular, make it possible to understand which simplifications yield the Kerr solution

On the variability of CO2 feed flows into CCS transportation and storage networks

The flexible operation of CO2 injection wells presents significant challenges. To avoid premature degradation of wells or loss of integrity it is imperative to understand the feed flow patterns that future CO2 transportation and storage networks will face. We use a unit commitment economic dispatch (UCED) model to study CCS operating regimes in low carbon energy systems scenarios that are characterised by high shares of weather dependent renewable power generation. Using the case study of Great Britain, we determine the extent to which flexible operation of CCS plants is required, resulting in variable CO2 flows that need to be accommodated by future CO2 transportation and storage networks. We find that around 21% and 12% of the net flow rate changes over 6h-periods in the core scenario have greater amplitudes than 30% and 50% of nominal flow, respectively. When changes are averaged over two consecutive blocks of 6 h, representing the smoothing effect achievable via line-packing over a pipeline of reasonable length and diameter, around 9% of the net changes have greater amplitudes than 40% of nominal flow. Given the high and frequent fluctuations in feed flows across all considered scenarios, further research is urgently required on the capability of transportation and storage networks to accommodate variable CO2 flow rates.</p

Cosmological evolution with negative energy densities

For general number of spatial dimensions we investigate the cosmological dynamics driven by a cosmological constant and by a source with barotropic equation of state. It is assumed that for both those sources the energy density can be either positive or negative. Exact solutions of the cosmological equations are provided for flat models. For models with curved space and with zero cosmological constant the general solutions are expressed in terms of the hypergeometric function. The qualitative evolution is described for all values of the equation of state parameter. We specify the values of that parameter and the combinations of the signs for the cosmological constant and matter energy density for which the cosmological dynamics is nonsingular. An example is considered with positive cosmological constant and negative matter energy density induced by the polarization of the hyperbolic vacuum.Comment: 12 pages, 3 figures. Discussion and references added, accepted for publication in Astrophysic

Epidemiological aspects of recruitment of male volunteers for non-invasive urodynamics

Introduction: We studied epidemiological aspects of recruitment of volunteers for a non-invasive urodynamic study. Materials and Methods: 9,236 volunteers were invited by 20 general practitioners (GPs), using two different recruitment methods, i.e. by mail only, or during a subsequent visit to the GP's office. Factors influencing the response rates were analyzed. We also tested how much the recruited population of volunteers differed from the general population, by comparing it to another, proven representative study carried out earlier in 1,662 subjects. Results: In the recruited population the prostate volumes were not significantly different from the proven representative study, but the symptom score was statistically significantly higher, although the difference was so small it may be called clinically irrelevant. Recruitment of volunteers in two steps, i.e. asking them first to visit the GP's office, and inviting them there to visit the outpatient clinic, rather than directly inviting them (in writing) to the clinic seemed to lead to a higher response, although this effect could not be statistically discriminated from the difference in response rates between GPs. Conclusion: The population recruited was not urologically different from the general population. The response depended on age, being highest around the age of 60, and increased with social economic status. It also depended on the GP who recruited the subjects, and/or on the recruitment method. Copyrigh