Results 61 to 70 of about 6,704,491 (163)
Cosmological Constraints on Brans-Dicke Theory [PDF]
Physical Review Letters, 2014 We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using Cosmic Microwave Background data from Planck.We consider two types of models. First, the initial condition of the scalar field is fixed to give the same effective gravitational strength $G_{eff}$ today as the one measured on the Earth, $G_N$.
Avilez, A. +3 more
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Phenomenology, astrophysics and cosmology of theories with submillimeter dimensions and TeV scale quantum gravity [PDF]
, 1998 We recently proposed a solution to the hierarchy problem not relying on low-energy supersymmetry or technicolor. Instead, the problem is nullified by bringing quantum gravity down to the TeV scale.
N. Arkani-Hamed, S. Dimopoulos, G. Dvali
semanticscholar +1 more source
String Theory and Primordial Cosmology [PDF]
, 2014 17 pages, 5 figures, published in "Springer Handbook of Spacetime", ed. by A. Ashtekar and V.
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String theory and the first half of the universe [PDF]
Journal of Cosmology and Astroparticle PhysicsWe perform a detailed study of stringy moduli-driven cosmologies between the end of inflation and the commencement of the Hot Big Bang, including both the background and cosmological perturbations: a period that can cover half the lifetime of the ...
Fien Apers +4 more
semanticscholar +1 more source
Renormalized cosmological perturbation theory
Physical Review D, 2006 We develop a new formalism to study nonlinear evolution in the growth of large-scale structure, by following the dynamics of gravitational clustering as it builds up in time. This approach is conveniently represented by Feynman diagrams constructed in terms of three objects: the initial conditions (e.g.
Crocce, M., Scoccimarro, R.
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Linearisation with Cosmological Perturbation Theory
, 2011 14 pages, 8 ...
Kitaura, F., Angulo, R.
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Accelerating cosmology in Rastall's theory
Il Nuovo Cimento B, 2009 In an attempt to look for a viable mechanism leading to a present-day accelerated expansion, we investigate the possibility that the observed cosmic speed up may be recovered in the framework of the Rastall's theory, relying on the non-conservativity of the stress-energy tensor, i.e. $T^μ_{ν; μ} \neq 0$.
Capone M. +2 more
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Modified Friedmann cosmologies—Theory and observations
Annals of Physics, 2005 We investigate a class of Cardassian scenarios of the universe evolution in notions of the qualitative theory of dynamical systems. This theory allows us to analyze all solutions for all possible initial conditions on the phase plane. In the Cardassian models we find that big-rip singularities are present as a typical behavior in the future if $n<0$.
Szydłowski, Marek, Czaja, Wojciech
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Perturbation Theory in Nonstandard Cosmology
Advances in Astrophysics, 2019 We explore a nonstandard model for the Universe in which we take a vacuum solution of Einstein’s equation as background and introduce visible matter and radiation as perturbations. The perturbation theory is greatly simplified by using the mapping on the inner Schwarzschild solution.
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Scales and cosmological applications of M theory [PDF]
Physics Letters B, 1999 I review recent results in three topics of the M-world: (i) Scales. (ii) New dark matter candidates. (iii) Cosmological solutions from p-branes. The three topics are discussed in the framework of Hořava-Witten compactifications. Part (iii) includes comments on cosmological solutions in M-theory describing nucleation of universes through instanton ...
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