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Analytic solutions of scalar perturbations induced by scalar perturbations [PDF]
Journal of Cosmology and Astroparticle Physics, 2021 We study scalar perturbations induced by scalar perturbations through the non-linear interaction appearing at second order in perturbations. We derive analytic solutions of the induced scalar perturbations in a perfect fluid. In particular, we consider the perturbations in a radiation-dominated era and a matter-dominated era.
Keisuke Inomata
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Linear cosmological perturbations in scalar-tensor-vector gravity
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2020 We investigate the cosmological perturbations in the context of a Scalar-Tensor-Vector theory of Gravity known as MOG in the literature. Recent investigations show that MOG reproduces a viable background cosmological evolution comparable to ΛCDM. However,
Mahmood Roshan, Luca Amendola
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Scalar cosmological perturbations [PDF]
Classical and Quantum Gravity, 2012 Scalar perturbations of Friedmann-Lemaitre cosmologies can be analyzed in a variety of ways using Einstein's field equations, the Ricci and Bianchi identities, or the conservation equations for the stress-energy tensor, and possibly introducing a timelike reference congruence.
Uggla, Claes, Wainwright, John
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On multifluid perturbations in scalar–tensor cosmology [PDF]
International Journal of Modern Physics D, 2020 In this paper, the scalar–tensor theory is applied to the study of perturbations in a multifluid universe, using the [Formula: see text] covariant approach. Both scalar and harmonic decompositions are instituted on the perturbation equations. In particular, as an application, we study perturbations on a background Friedmann-Robertson-Walker (FRW ...
Joseph Ntahompagaze +3 more
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Scalar perturbations in scalar field quantum cosmology [PDF]
Physical Review D, 2009 In this paper it is shown how to obtain the simplest equations for the Mukhanov-Sasaki variables describing quantum linear scalar perturbations in the case of scalar fields without potential term. This was done through the implementation of canonical transformations at the classical level, and unitary transformations at the quantum level, without ever ...
Falciano, F. T., Pinto-Neto, Nelson
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Scalar perturbations through cycles [PDF]
Physical Review D, 2012 We analytically and numerically investigate the evolutions of the scalar perturbations through the cycles with nonsingular bounce. It is found that the amplitude of the curvature perturbation on large scale will be amplified cycle by cycle, and the isocurvature perturbations also obtain an amplification, but the rate of its amplification is slower than
Liu, Zhi-Guo, Piao, Yun-Song
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Properties of Scalar Perturbations Generated by Conformal Scalar Field [PDF]
Progress of Theoretical Physics Supplement, 2011 Prepared for "Gravity and Cosmology (GC2010)" workshop, Kyoto, Japan, May,24-July,16, 2010; 15 pages, 1 ...
Libanov, M., Mironov, S., Rubakov, V.
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Superradiance instabilities of charged black holes in Einstein-Maxwell-scalar theory
Journal of High Energy Physics, 2023 We study time evolutions of charged scalar perturbations on the background of a charged hairy black hole, in which the perturbations can be governed by a double-peak effective potential.
Guangzhou Guo +3 more
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Effective Field Theory for the perturbations of a slowly rotating black hole
Journal of High Energy Physics, 2021 We develop the effective theory for perturbations around black holes with scalar hair, in two directions. First, we show that the scalar-Gauss-Bonnet theory, often used as an example exhibiting scalar black hole hair, can be deformed by galileon ...
Lam Hui +3 more
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Cosmological perturbations with multiple scalar fields [PDF]
Physics Letters B, 2000 We consider the evolution of perturbed cosmological spacetime with multiple scalar fields in Einstein gravity. A complete set of scalar-type perturbation equations is presented in a gauge-ready form, and we derived the closed set of second-order differential equations in several useful forms.
Hwang, J., Noh, H.
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