Marginally deformed Starobinsky gravity

Codello, Alessandro; Joergensen, Jakob; Sannino, Francesco; Svendsen, Ole

doi:10.1007/jhep02(2015)050

Cited by 43 publications

(61 citation statements)

References 28 publications

(42 reference statements)

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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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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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“…In the light of the possibility that r can be larger than the Starobinsky model prediction of r ∼ 0.003, generalisations of the Starobinsky model are of interest. The quantum correction on φ 4 -potential in Jordan frame was studied in [102,103,104,105] where they have shown the equivalence of the ξφ 2 R + λφ 4(1+γ) model with 1 M 2 R β model. The generalized Starobinsky model with R p correction has been studied in the ref.…”

Section: +007mentioning

confidence: 99%

Testing theories of gravity and supergravity with inflation and observations of the cosmic microwave background

Chakravarty

Mohanty

Lambiase

2017

Int. J. Mod. Phys. D

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Abstract. Cosmological and astrophysical observations lead to the emerging picture of a universe that is spatially flat and presently undertaking an accelerated expansion. The observations supporting this picture come from a range of measurements encompassing estimates of galaxy cluster masses, the Hubble diagram derived from type-Ia supernovae observations, the measurements of Cosmic Microwave Background radiation anisotropies, etc. The present accelerated expansion of the universe can be explained by admitting the existence of a cosmic fluid, with negative pressure. In the simplest scenario this unknown component of the universe, the Dark Energy, is represented by the cosmological constant (Λ), and accounts for about 70% of the global energy budget of the universe. The remaining 30% consists of a small fraction of baryons (4%) with the rest cold Dark Matter (CDM). The Lambda Cold Dark Matter (ΛCDM) model, i.e. General Relativity with cosmological constant, is in good agreement with observations. It can be assumed as the first step towards a new standard cosmological model. However, despite the satisfying agreement with observations, the ΛCDM model presents several lacks of congruence and shortcomings, and therefore theories beyond Einsteins General Relativity are called for. Many extensions of Einstein's theory of gravity have been studied and proposed with various motivations like the quest for a quantum theory of gravity to extensions of anomalies in observations at the solar system, galactic and cosmological scales. These extensions include adding higher powers of Ricci curvature R, coupling the Ricci curvature with scalar fields and generalized functions of R. In addition when viewed from the perspective of Supergravity (SUGRA) many of these theories may originate from the same SUGRA theory, but interpreted in different frames. SUGRA therefore serves as a good framework for organizing and generalizing theories of gravity beyond General Relativity. All these theories when applied to inflation (a rapid expansion of early Universe in which primordial gravitational waves might be generated and might still be detectable by the imprint they left or by the ripples that persist today) can have distinct signatures in the Cosmic Microwave Background radiation temperature and polarization anisotropies. We give a review of ΛCDM cosmology and survey the theories of gravity beyond Einsteins General Relativity, specially which arise from SUGRA, and study the consequences of these theories in the context of inflation and put bounds on the theories and the parameters therein from the observational experiments like PLANCK, Keck/BICEP etc. The possibility of testing these theories in the near future in CMB observations and new data coming from colliders like the LHC, provides an unique opportunity for constructing verifiable models of particle physics and General Relativity.

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“…(1.2), with 1 < n < 2 according to Ref. [16]) during the Universe evolution from GUT scales to the transition time t * . The latter characterizes the instant in which the Universe passes from the cosmic evolution described by f (R) cosmology to the cosmic evolution described by the standard cosmological model (see below).…”

Section: Field Equations In F (R) Gravitymentioning

confidence: 99%

“…[14,15] show that the Starobinsky model is in good agreement with the BICEP2 data. Moreover, sizable primordial tensor modes can be generated in (marginally deformed) models of the form (1.2), provided 1 < n < 2 [16] (more specifically in [16] it is shown that if inflation is driven by f (R) gravity, then a natural form for this function is (1.2), where the value of n could be related to the microscopic theory dictating the trace-log quantum corrections). The main point is to rewrite the f (R) action in the Einstein frame, which implies the appearance of a scalar field.…”

Section: Introductionmentioning

confidence: 99%

Cosmological evolution of thermal relic particles inf(R)gravity

et al. 2015

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By considering f (R) gravity models, the cosmic evolution is modified with respect to the standard ΛCDM scenario. In particular, the thermal history of particles results modified. In this paper, we derive the evolution of relics particles (WIMPs) assuming a reliable f (R) cosmological solution and taking into account observational constraints. The connection to the PAMELA experiment is also discussed. Results are consistent with constraints coming from BICEP2 and PLANCK experiments.

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Marginally deformed Starobinsky gravity

Cited by 43 publications

References 28 publications

Asymptotically safe inflation from quadratic gravity

Asymptotically safe inflation from quadratic gravity

Testing theories of gravity and supergravity with inflation and observations of the cosmic microwave background

Cosmological evolution of thermal relic particles inf(R)gravity

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