Homogeneous cosmos of Weyssenhoff fluid in Einstein-Cartan space

J, Duarte de Oliveira; Teixeira, A. F. da F.; Tiomno, J.

doi:10.1103/physrevd.34.3661

Cited by 23 publications

(20 citation statements)

References 34 publications

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“…no closed time-like curves are allowed for the space-time. This is an example of the causal cosmological solutions suggested in [5]. One can see that value of B does not change our estimations for the order of the tachyon mass, so that, qualitatively, our conclusions will not depend on the causality of the background space-time.…”

Section: Scalar Fieldsupporting

confidence: 60%

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Stability of tardyons and tachyons in the rotating and expanding Universe

Konoplya

Zhidenko

2012

Phys. Rev. D

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In the present paper we analyze the spectrum of quasinormal modes for massive scalar and Dirac fields, allowing for both tardyonic (µ 2 > 0) and tachyonic (µ 2 < 0) masses, in the expanding and rotating cosmological background. The spectrum found shows a number of peculiar features, which are absent in the Minkowski space-time. A hypothetical particle that moves faster than light, a tachyon, is known to be classically unstable in the Minkowski space-time. This instability has its analog at the quantum level: small vacuum fluctuations of the field lead to the unbounded growth of the amplitude, so that the appearance of the real tachyons in the spectrum means that there is catastrophic instability in the theory. It has been conjectured a long time ago that possibly the lightest particles with nonzero mass, the neutrino, may be a tachyon. Here we shall show that in the rotating and expanding Universe tachyons are stable if their mass is less than some constant, which is related to the Universe's rotation and expansion scales. The current upper bound on the rotation scale gives us a very small upper bound on the tachyon's mass which is many orders less than the mass of the electron. This might explain why only very light particles have the chance of becoming tachyons. It is shown that the spectrum of the "normal" (µ 2 > 0) Dirac field has a discontinuity as a function of the z-component of the wave vector kz at kz = 0.

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Section: Scalar Fieldsupporting

confidence: 60%

“…which includes both causal and noncausal generalizations [5,[12][13][14] of the classical Gödel solution [4]. The Gödel metric is reproduced if B 2 = 1/2 and a(t) = 1.…”

Section: Scalar Fieldmentioning

confidence: 99%

Stability of tardyons and tachyons in the rotating and expanding Universe

Konoplya

Zhidenko

2012

Phys. Rev. D

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“…The coordinates (t, r, φ, z) are defined in the ranges: along the direction of the rotation vector (the z-axis) [32]. Throughout this article, we shall refer to this torsion as polarized (aligned) along the rotation vector.…”

Section: Ical Defectmentioning

confidence: 99%

Fermions in Gödel-type background space-times with torsion and the Landau quantization

Garcia¹,

Oliveira²,

Bakke³

et al. 2017

Eur. Phys. J. Plus

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In this paper, we analyze Dirac fermions in Gödel-type background space-times with torsion. We also consider the Gödel-type spacetimes embedded in a topological defect background. We show that relativistic bound states solutions to the Dirac equation can be obtained by dealing with three cases of the Gödel-type solutions with torsion, where a cosmic string passes through these three cases of the space-time. We obtain the relativistic energy levels for all cases of the Gödel-type solutions with torsion with a cosmic string, where we show that there exists an analogy with the Landau levels for Dirac particles. We also show that the presence of torsion in the space-time yields new contributions to the relativistic spectrum of energies and that the presence of the topological defect modifies the degeneracy of the relativistic energy levels.

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“…These solutions in general have non-zero cosmological constant and stress-energy tensor; if we use as sources a combination of perfect fluid, U (1) gauge fields and/or a massless scalar, one can cover the range [24] −∞ < l 2 ≤ Ω 2 . The solutions with l 2 > Ω 2 can be realized [27], if we allow for solutions with torsion; we will touch upon these metrics only briefly.…”

Section: A Family Of Gödel-type Solutionsmentioning

confidence: 99%

Gödel-type universes and the Landau problem

Drukker

Fiol

Simón

2004

J. Cosmol. Astropart. Phys.

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We point out a close relation between a family of Gödel-type solutions of 3+1 General Relativity and the Landau problem in S 2 , R 2 and H 2 ; in particular, the classical geodesics correspond to Larmor orbits in the Landau problem. We discuss the extent of this relation, by analyzing the solutions of the Klein-Gordon equation in these backgrounds. For the R 2 case, this relation was independently noticed in hep-th/0306148. Guided by the analogy with the Landau problem, we speculate on the possible holographic description of a single chronologically safe region.

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Homogeneous cosmos of Weyssenhoff fluid in Einstein-Cartan space

Cited by 23 publications

References 34 publications

Stability of tardyons and tachyons in the rotating and expanding Universe

Stability of tardyons and tachyons in the rotating and expanding Universe

Fermions in Gödel-type background space-times with torsion and the Landau quantization

Gödel-type universes and the Landau problem

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