Inflation in scale-invariant theories of gravity

Rinaldi, Massimiliano; Cognola, Guido; Vanzo, Luciano; Zerbini, Sergio

doi:10.1103/physrevd.91.123527

Cited by 64 publications

(53 citation statements)

References 44 publications

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“…To begin with, it has been shown that the most likely form of fðRÞ, in the absence of matter, compatible with the measured spectral indices is f ∼ R 2−δ , with 0 < δ ≪ 1 [9]; see also [10]. Other studies showed that scale-invariant gravity with quantum corrections can reproduce inflation and spectral indices in line with current observations [11] in the absence of inflaton or any other kind of matter fluid. Quantum corrections in the context of inflation have been recently considered in various approaches; see, e.g., [12][13][14][15].…”

Section: Introductionsupporting

confidence: 56%

Inflation and reheating in theories with spontaneous scale invariance symmetry breaking

Rinaldi

Vanzo

2016

Phys. Rev. D

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We study a scale-invariant model of quadratic gravity with a nonminimally coupled scalar field. We focus on cosmological solutions and find that scale invariance is spontaneously broken and a mass scale naturally emerges. Before the symmetry breaking, the Universe undergoes an inflationary expansion with nearly the same observational predictions of Starobinsky's model. At the end of inflation, the Hubble parameter and the scalar field converge to a stable fixed point through damped oscillations and the usual Einstein-Hilbert action is recovered. The oscillations around the fixed point can reheat the Universe in various ways, and we study in detail some of these possibilities.

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Section: Introductionsupporting

confidence: 56%

Inflation and reheating in theories with spontaneous scale invariance symmetry breaking

Rinaldi

Vanzo

2016

Phys. Rev. D

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“…Various descriptions of inflationary models in terms of scalar field models [53] and perfect fluid as well as F (R) gravity [54] have been examined. Moreover, the effects of quantum corrections on inflation have been explored in References [55][56][57]. We note that the BICEP2 experiment has recently detected the B-mode polarization of the cosmic microwave background (CMB) radiation with the tensor to scalar ratio r = 0.20…”

Section: Extension Of the Starobinsky Inflation Modelmentioning

confidence: 99%

Inflationary Cosmology in Modified Gravity Theories

2015

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We review inflationary cosmology in modified gravity such as R 2 gravity with its extensions in order to generalize the Starobinsky inflation model. In particular, we explore inflation realized by three kinds of effects: modification of gravity, the quantum anomaly, and the R 2 term in loop quantum cosmology. It is explicitly demonstrated that in these inflationary models, the spectral index of scalar modes of the density perturbations and the tensor-to-scalar ratio can be consistent with the Planck results. Bounce cosmology in F (R) gravity is also explained.Keywords: dark energy; cosmology; particle-theory and field-theory models of the early Universe; modified theories of gravity; models beyond the standard model; loop quantum gravity; quantum geometry; spin foams; mathematical and relativistic aspects of cosmology

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“…k 2 ∼ R (see also [41]). In a recent investigation a similar approach has been successfully applied to study the quantum gravity modifications of the Starobinsky model [42] (see also [43][44][45][46][47][48] for other examples of quantum deformed quadratic gravity inflationary models).…”

Section: Introductionmentioning

confidence: 99%

Asymptotically safe inflation from quadratic gravity

Platania¹,

Bonanno²

2016

Proceedings of Proceedings of the Corfu Summer Institute 2015 — PoS(CORFU2015)

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Asymptotically Safe theories of gravity have recently received much attention. In this work we discuss a class of inflationary models derived from quantum-gravity modification of quadratic gravity according to the induced scaling around the non-Gaussian fixed point at very high energies. It is argued that the presence of a three dimensional ultraviolet critical surface generates operators of non-integer power of the type R 2−θ/2 in the effective Lagrangian, where θ > 0 is a critical exponent. The requirement of a successful inflationary model in agreement with the recent Planck 2015 data puts important constraints on the strenght of this new type of couplings.

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Inflation in scale-invariant theories of gravity

Cited by 64 publications

References 44 publications

Inflation and reheating in theories with spontaneous scale invariance symmetry breaking

Inflation and reheating in theories with spontaneous scale invariance symmetry breaking

Inflationary Cosmology in Modified Gravity Theories

Asymptotically safe inflation from quadratic gravity

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