Results 11 to 20 of about 973 (226)
On the symmetries of cosmological perturbations [PDF]
Journal of Cosmology and Astroparticle Physics, 2020 The space of inflationary models is vast, containing wide varieties of mechanisms, symmetries, and spectra of particles. Consequently, the space of observational signatures is similarly complex. Hence, it is natural to look for boundaries of the space of models and their signatures.
Green, Daniel, Pajer, Enrico
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Cosmological perturbations in antigravity [PDF]
Physical Review D, 2014 15 pages, a few references ...
Oltean, Marius, Brandenberger, Robert
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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 cosmological perturbations of quasidilaton [PDF]
Classical and Quantum Gravity, 2013 A theory of the quasidilaton is an extension of massive gravity by a scalar field, nonlinearly realizing a certain new global symmetry of the Lagrangian. It has been shown that unlike pure massive gravity, this theory does admit homogeneous and isotropic spatially flat solutions.
D'Amico, Guido +3 more
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Cosmological perturbations in Palatini formalism [PDF]
Journal of Cosmology and Astroparticle Physics, 2021 29 pages, Comments welcome!
Yamaguchi, Masahide +3 more
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Matching conditions for cosmological perturbations [PDF]
Physical Review D, 1995 We derive the matching conditions for cosmological perturbations in a Friedmann Universe where the equation of state undergoes a sharp jump, for instance as a result of a phase transition. The physics of the transition which is needed to follow the fate of the perturbations is clarified.
Deruelle, Nathalie, Mukhanov, V. F.
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COSMOLOGICAL PERTURBATIONS IN RENORMALIZATION GROUP DERIVED COSMOLOGIES [PDF]
International Journal of Modern Physics D, 2004 A linear cosmological perturbation theory of an almost homogeneous and isotropic perfect fluid Universe with dynamically evolving Newton constant G and cosmological constant Λ is presented. A gauge invariant formalism is developed by means of the covariant approach, and the acoustic propagation equations governing the evolution of the comoving ...
Bonanno, A., Reuter, M.
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Entanglement entropy of cosmological perturbations [PDF]
Physical Review D, 2020 We show that the entropy of cosmological perturbations originating as quantum vacuum fluctuations in the very early universe, including the contribution of the leading nonlinear interactions, can be viewed as momentum space entanglement entropy between sub- and super-Hubble modes.
Suddhasattwa Brahma +2 more
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Cosmological perturbations [PDF]
Physics Reports, 2009 We review the study of inhomogeneous perturbations about a homogeneous and isotropic background cosmology. We adopt a coordinate based approach, but give geometrical interpretations of metric perturbations in terms of the expansion, shear and curvature of constant-time hypersurfaces and the orthogonal timelike vector field.
Malik, KA, Wands, D
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The MESS of cosmological perturbations
Physics Letters B, 2018 We introduce two new effective quantities for the study of comoving curvature perturbations ζ: the space dependent effective sound speed (SESS) and the momentum dependent effective sound speed (MESS).
Antonio Enea Romano +1 more
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