Power law Starobinsky model of inflation from no-scale SUGRA

Chakravarty, Girish Kumar; Mohanty, Sanghamitra

doi:10.1016/j.physletb.2015.04.056

Cited by 24 publications

(23 citation statements)

References 90 publications

(118 reference statements)

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“…[1] as well as to (b) aµ 4 (R/µ 2 ) 2−b . Inflation built based on the former form was also studied in [38,40,43], while on the latter formin [36,[44][45][46]. One should point out however, that for any finite b these models are not equivalent to (3).…”

Section: The Modelmentioning

confidence: 99%

“…where t e denotes the time at the end of inflation (at which E = 1), and φ Ee = φ E (t e ), When taken together, and these two sets of (parametric) relations tell us how n s , r and α depend on N . Unfortunately, the form of the effective potential (35) is rather complicated such that we were unable to perform the integral (44). Nevertheless, with a help of the symbolic package Mathematica, we were able to plot the relevant curves.…”

Section: B Cosmological Perturbations In Our Modelmentioning

confidence: 99%

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Inflation in an effective gravitational model and asymptotic safety

2018

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Republic of Tatarstan, Russian FederationWe consider an inflationary model motivated by quantum effects of gravitational and matter fields near the Planck scale. Our Lagrangian is a re-summed version of the effective Lagrangian recently obtained by Demmel, Saueressig and Zanusso [1] in the context of gravity as an asymptotically safe theory. It represents a refinedwhere R is the Ricci scalar, a and b are constants and µ is an energy scale. By implementing the COBE normalisation and the Planck constraint on the scalar spectrum, we show that increasing b leads to an increased value of both the scalar spectral index n s and the tensor-to-scalar ratio r. Requiring n s to be consistent with the Planck collaboration upper limit, we find that r can be as large as r 0.01, the value possibly measurable by Stage IV CMB ground experiments and certainly from future dedicated space missions. The predicted running of the scalar spectral index α = dn s /d ln(k) is still of the order −5 × 10 −4 (as in the Starobinsky model), about one order of magnitude smaller than the current observational bound. * Electronic address: L.Liu1@uu.nl † Electronic address: t.prokopec@uu.nl ‡ Electronic address: alstar@landau.ac.ru arXiv:1806.05407v1 [gr-qc]

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Section: The Modelmentioning

confidence: 99%

Section: B Cosmological Perturbations In Our Modelmentioning

confidence: 99%

Inflation in an effective gravitational model and asymptotic safety

2018

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“…For example, considering the f (R) gravity, with f (R) = R + a R n , we have found that IceCube data and DM relic abundance can be explained provided n < 1, However, such a value is not favored by recent Planck release, which require n > 1 (and in fact the Starobisnky model n = 2 is one of the favorite candidate for Inflation) [114,115]. Results here discussed do not allow to distinguish between f (T ) and BD theories of gravity.…”

Section: Discussionmentioning

confidence: 98%

PeV IceCube signals and Dark Matter relic abundance in modified cosmologies

2018

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The discovery by the IceCube experiment of a high-energy astrophysical neutrino flux with energies of the order of PeV, has opened new scenarios in astroparticles physics. A possibility to explain this phenomenon is to consider the minimal models of Dark Matter (DM) decay, the 4-dimensional operator ∼ y αχ L L α H χ , which is also able to generate the correct abundance of DM in the Universe. Assuming that the cosmological background evolves according to the standard cosmological model, it follows that the rate of DM decay χ ∼ |y αχ | 2 needed to get the correct DM relic abundance ( χ ∼ 10 −58 ) differs by many orders of magnitude with respect that one needed to explain the IceCube data ( χ ∼ 10 −25 ), making the four-dimensional operator unsuitable. In this paper we show that assuming that the early Universe evolution is governed by a modified cosmology, the discrepancy between the two the DM decay rates can be reconciled, and both the IceCube neutrino rate and relic density can be explained in a minimal model.

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“…We now study a model R + 2 and so we call it as power law Starobinsky model [99]. M and β are the two dimensionless parameters.…”

Section: The Power Law Model R + R βmentioning

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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Power law Starobinsky model of inflation from no-scale SUGRA

Cited by 24 publications

References 90 publications

Inflation in an effective gravitational model and asymptotic safety

Inflation in an effective gravitational model and asymptotic safety

PeV IceCube signals and Dark Matter relic abundance in modified cosmologies

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

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