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Non-linear perturbations of cosmological scalar fields [PDF]
Journal of Cosmology and Astroparticle Physics, 2007 We present a covariant formalism for studying nonlinear perturbations of scalar fields. In particular, we consider the case of two scalar fields and introduce the notion of adiabatic and isocurvature covectors. We obtain differential equations governing the evolution of these two covectors, as well as the evolution equation for the covector associated ...
Langlois, David, Vernizzi, F.
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The simplest wormhole in Rastall and k-essence theories
European Physical Journal C: Particles and Fields, 2021 The geometry of the Ellis–Bronnikov wormhole is implemented in the Rastall and k-essence theories of gravity with a self-interacting scalar field. The form of the scalar field potential is determined in both cases.
Kirill A. Bronnikov +3 more
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Charged scalar quasi-normal modes for linearly charged dilaton-Lifshitz solutions
Physics Letters B, 2017 Most available studies of quasi-normal modes for Lifshitz black solutions are limited to the neutral scalar perturbations. In this letter, we investigate the wave dynamics of massive charged scalar perturbation in the background of (3+1)-dimensional ...
M. Kord Zangeneh +3 more
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Stability of generalized Einstein-Maxwell-scalar black holes
Journal of High Energy Physics, 2022 We study the stability of static black holes in generalized Einstein-Maxwell-scalar theories. We derive the master equations for the odd and even parity perturbations.
Radouane Gannouji +1 more
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Generalized disformal invariance of cosmological perturbations with second-order field derivatives
Physics Letters B, 2021 We investigate how the comoving curvature and tensor perturbations are transformed under the generalized disformal transformation with the second-order covariant derivatives of the scalar field, where the free functions depend on the fundamental elements
Masato Minamitsuji
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Charged scalar perturbations around Garfinkle–Horowitz–Strominger black holes
Nuclear Physics B, 2015 We examine the stability of the Garfinkle–Horowitz–Strominger (GHS) black hole under charged scalar perturbations. Employing the appropriate numerical methods, we show that the GHS black hole is always stable against charged scalar perturbations. This is
Cheng-Yong Zhang +2 more
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Warm Inflation and Scalar Perturbations of the Metric [PDF]
General Relativity and Gravitation, 2001 A second-order expansion for the quantum fluctuations of the matter field was considered in the framework of the warm inflation scenario. The friction and Hubble parameters were expended by means of a semiclassical approach. The fluctuations of the Hubble parameter generates fluctuations of the metric.
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Scalar perturbations in braneworld cosmology [PDF]
Journal of Cosmology and Astroparticle Physics, 2007 We study the behaviour of scalar perturbations in the radiation-dominated era of Randall-Sundrum braneworld cosmology by numerically solving the coupled bulk and brane master wave equations. We find that density perturbations with wavelengths less than a critical value (set by the bulk curvature length) are amplified during horizon re-entry. This means
Cardoso, Antonio +3 more
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A perturbative analysis of interacting scalar field cosmologies
Classical and Quantum Gravity, 2022 Abstract Scalar field cosmologies with a generalized harmonic potential are investigated in flat and negatively curved Friedmann–Lemaître–Robertson–Walker and Bianchi I metrics. An interaction between the scalar field and matter is considered.
Genly Leon +3 more
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Scalar Perturbations and Conformal Transformation
, 1996 Latex, 14 ...
Fabris, Júlio César, Tossa, Joël
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