Scalar Casimir effect in a high-dimensional cosmic dispiration spacetime

Mota, Herondy F. Santana; Mello, E. R. Bezerra de; Bakke, K.

doi:10.1142/s0218271818501079

Cited by 18 publications

(28 citation statements)

References 70 publications

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“…This component goes to zero as the distance from the cosmic string increases and to infinity as the distance decreases, in accordance with the asymptotic expressions (25) and (24), respectively. For this value of the cosmic string parameter, the divergences Rs n = 1 occur at R = 1 and R 1.4, as we can see on the plot of Fig.1.…”

Section: A No Boundarysupporting

confidence: 84%

Induced Brownian motion by the Friedmann–Robertson–Walker spacetime in the presence of a cosmic string

Mota

Mello

2020

Eur. Phys. J. Plus

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In this paper we investigate the quantum Brownian motion of a massive scalar point particle induced by the FRW spacetime in the presence of a linear topological defect named cosmic string.In addition, we also consider a flat boundary orthogonal to the defect to analyse its effect on the particle's motion. For both cases we found exact expressions for the renormalized mean square deviation of the particle velocity, the quantity that measures the induced Brownian motion, and obtain asymptotic expressions when the point particle is near and far away from the cosmic string and the boundary. Furthermore, in both cases, there appears divergencies in the mean square deviation of the particle velocity coming from a time interval that correspond to a round trip of the massive point particle between its position and the cosmic string/flat boundary. The number of divergencies depends upon the radial position of the particle and the parameter associated with the cosmic string in the case without boundary, and upon this parameter and the radial and z positions of the particle in the case with boundary. * Electronic address: hmota@fisica.ufpb.br † Electronic address: emello@fisica.ufpb.br arXiv:1904.04634v1 [hep-th]

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Section: A No Boundarysupporting

confidence: 84%

Induced Brownian motion by the Friedmann–Robertson–Walker spacetime in the presence of a cosmic string

Mota

Mello

2020

Eur. Phys. J. Plus

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“…Cosmic string type solutions on AdS bulk and in braneworld models have been considered, for example, in [6,7]. The polarization of quantum vacuum around cosmic strings has been mainly considered for the background Minkowski geometry (see, for instance, references given in [8,9]). The combined effects of the gravitational field and of a cosmic string on the local characteristics of scalar, fermionic and electromagnetic vacua in the case of the de Sitter (dS) background were discussed in [10].…”

Section: Introductionmentioning

confidence: 99%

Cosmic string and brane induced effects on the fermionic vacuum in AdS spacetime

Bellucci,

Santos,

de Mello

et al. 2022

Preprint

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We investigate the combined effects of a magnetic flux-carrying cosmic string and a brane on the fermionic condensate (FC) and on the vacuum expectation value (VEV) of the energymomentum tensor for a massive charged fermionic field in background of 5-dimensional anti-de Sitter (AdS) spacetime. The brane is parallel to the AdS boundary and it divides the space into two regions with distinct properties of the fermionic vacuum. For two types of boundary conditions on the field operator and for the fields realizing two inequivalent representations of the Clifford algebra, the brane-induced contributions in VEVs are explicitly separated. The VEVs are even periodic functions of the magnetic flux, confined in the core, with the period of flux quantum. Near the horizon the FC and the vacuum energy-momentum tensor are dominated by the branefree contribution, whereas the brane-induced part dominates in the region near the brane. Both the contributions vanish on the AdS boundary. At large distances from the cosmic string, the topological contributions in the VEVs, as functions of the proper distance, exhibit an inverse power-law decrease in the region between the brane and AdS horizon and an exponential decrease in the region between the brane and AdS boundary. We show that the FC and the vacuum energy density can be either positive or negative, depending on the distance from the brane. Applications are discussed in fermionic models invariant under the charge conjugation and parity transformation and also in Z 2 -symmetric braneworld models. By the limiting transition we derive the expressions of the FC and the vacuum energy-momentum tensor for a cosmic string on 5-dimensional Minkowski bulk in the presence of a boundary perpendicular to the string.

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“…Quantum vacuum fluctuation effects arise every time the quantum vacuum of a relativistic field (scalar, vector, fermionic) is somehow perturbed, either by the implementation of boundary conditions of some sort or by external fields [1][2][3][4]. These effects also take place in curved spacetimes, in principle, solely as a consequence of the existence of a nontrivial topology [2][3][4][5][6]. Evidently, boundary conditions or/and external fields can also be considered in these spacetimes with nontrivial topology, in which case an effect associated with each one of these ingredients, separately, comes about.…”

Section: Introductionmentioning

confidence: 99%

“…However, theoretically, many works have been done considering the Casimir effect in spacetime with nontrivial topology, along with boundary conditions [2][3][4]18]. In this context, other components of the energy-momentum tensor have also been considered [5,6,[26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Quantum vacuum fluctuation effects in a quasi-periodically identified conical spacetime

de Farias,

Mota

2020

Preprint

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We consider a quasi-periodically identified conical spacetime, like the one of a cosmic string or disclination, to investigate nonzero averaged quantum vacuum fluctuations effects on the energymomentum tensor and induced current density associated with a charged scalar field. We obtain exactly closed analytical expressions for the two-point Wightman function and the vacuum expectation value of the field squared, as well as for all components of the energy-momentum tensor. As to the induced current density, due to the quasi-periodic condition used, the only nonzero averaged component found is the azimuthal one. We also compare our results with previous ones found in literature.

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Scalar Casimir effect in a high-dimensional cosmic dispiration spacetime

Cited by 18 publications

References 70 publications

Induced Brownian motion by the Friedmann–Robertson–Walker spacetime in the presence of a cosmic string

Induced Brownian motion by the Friedmann–Robertson–Walker spacetime in the presence of a cosmic string

Cosmic string and brane induced effects on the fermionic vacuum in AdS spacetime

Quantum vacuum fluctuation effects in a quasi-periodically identified conical spacetime

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