Electromagnetic Casimir densities for a cylindrical shell on de Sitter space

Saharian, A. A.; Manukyan, V.; Saharyan, N. A.

doi:10.1142/s0217751x16501839

Cited by 5 publications

(2 citation statements)

References 57 publications

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“…the latter equation is reduced to ∂ l (rA l ) = 0 and coincides with the corresponding equation in the Minkowski bulk. The procedure to find the complete set of solutions to the Maxwell equations is similar to that we have already described in [18] for the bulk in the absence of the cosmic string. The only difference is in the periodicity condition along the azimuthal direction φ.…”

Section: Cylindrical Electromagnetic Modesmentioning

confidence: 99%

Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime

2017

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The electromagnetic field correlators are evaluated around a cosmic string in background of (D + 1)-dimensional dS spacetime assuming that the field is prepared in the Bunch-Davies vacuum state. The correlators are presented in the decomposed form where the string-induced topological parts are explicitly extracted. With this decomposition, the renormalization of the local vacuum expectation values (VEVs) in the coincidence limit is reduced to the one for dS spacetime in the absence of the cosmic string. The VEVs of the squared electric and magnetic fields, and of the vacuum energy density are investigated. Near the string they are dominated by the topological contributions and the effects induced by the background gravitational field are small. In this region, the leading terms in the topological contributions are obtained from the corresponding VEVs for a string on the Minkowski bulk multiplying by the conformal factor. At distances from the string larger than the curvature radius of the background geometry, the pure dS parts in the VEVs dominate. In this region, for spatial dimensions D > 3, the influence of the gravitational field on the topological contributions is crucial and the corresponding behavior is essentially different from that for a cosmic string on the Minkowski bulk. There are well-motivated inflationary models which produce cosmic strings. We argue that, as a consequence of the quantum-to-classical transition of super-Hubble electromagnetic fluctuations during inflation, in the post-inflationary era these strings will be surrounded by large-scale stochastic magnetic fields. These fields could be among the distinctive features of the cosmic strings produced during the inflation and also of the corresponding inflationary models.

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Section: Cylindrical Electromagnetic Modesmentioning

confidence: 99%

Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime

2017

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“…It has been shown that the influence of the gravitational field on the local characteristics of the vacuum state is essential at distance from the boundaries larger than the curvature radius of the background geometry. The VEVs of the field squared and energy-momentum tensor for scalar and electromagnetic fields induced by a cylindrical boundary in dS bulk have been investigated in [22,23]. Another class of exactly solvable problems correspond to spherical boundaries.…”

Section: Introductionmentioning

confidence: 99%

Casimir densities induced by a sphere in the hyperbolic vacuum of de Sitter spacetime

Saharian,

Petrosyan

2021

Preprint

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Complete set of modes and the Hadamard function are constructed for a scalar field inside and outside a sphere in (D + 1)-dimensional de Sitter spacetime foliated by negative constant curvature spaces. We assume that the field obeys Robin boundary condition on the sphere. The contributions in the Hadamard function induced by the sphere are explicitly separated and the vacuum expectation values (VEVs) of the field squared and energy-momentum tensor are investigated for the hyperbolic vacuum. In the flat spacetime limit the latter is reduced to the conformal vacuum in the Milne universe and is different from the maximally symmetric Bunch-Davies vacuum state. The vacuum energy-momentum tensor has a nonzero off-diagonal component that describes the energy flux in the radial direction. The latter is a purely sphere-induced effect and is absent in the boundary-free geometry. Depending on the constant in Robin boundary condition and also on the radial coordinate, the energy flux can be directed either from the sphere or towards the sphere. At early stages of the cosmological expansion the effects of the spacetime curvature on the sphere-induced VEVs are weak and the leading terms in the corresponding expansions coincide with those for a sphere in the Milne universe. The influence of the gravitational field is essential at late stages of the expansion. Depending on the field mass and the curvature coupling parameter, the decay of the sphere-induced VEVs, as functions of the time coordinate, is monotonic or damping oscillatory. At large distances from the sphere the fall-off of the sphere-induced VEVs, as functions of the geodesic distance, is exponential for both massless and massive fields.

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Casimir densities induced by a sphere in the hyperbolic vacuum of de Sitter spacetime

Saharian

Petrosyan

2021

Phys. Rev. D

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Electromagnetic Casimir densities for a cylindrical shell on de Sitter space

Cited by 5 publications

References 57 publications

Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime

Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime

Casimir densities induced by a sphere in the hyperbolic vacuum of de Sitter spacetime

Casimir densities induced by a sphere in the hyperbolic vacuum of de Sitter spacetime

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