Inflation due to non-minimal coupling of <i>f</i>(<i>R</i>) gravity to a scalar field

Budhi, Romy H. S.

doi:10.1088/1742-6596/1127/1/012018

Cited by 12 publications

(10 citation statements)

References 27 publications

(31 reference statements)

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“…then we obtain, in the "Metric" formulation, where the Christoffel symbols are defined in terms of the metric and thus are not independent, and the corresponding affine connection is defined to be the Levi-Civita one, the following [33]:…”

Section: Analysis Of the Basic Modelmentioning

confidence: 99%

Palatini f(R) Gravity and Variants of k-/Constant Roll/Warm Inflation within Variation of Strong Coupling Scenario

et al. 2022

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We show that upon applying Palatini f(R), characterized by an αR2 term, within a scenario motivated by a temporal variation of strong coupling constant, then one obtains a quadratic kinetic energy. We do not drop this term, but rather study two extreme cases: α<<1 and α>>1. In both cases, one can generate a kinematically-induced inflationary paradigm. In order to fit the Planck 2018 data, the α>>1 case, called k-inflation, requires a fine tuning adjustment with nonvanishing nonminimal coupling to gravity parameter ξ, whereas the α<<1 case, studied in the constant-roll regime, can fit the data for vanishing ξ. The varying strong coupling inflation scenario remains viable when implemented through a warm inflation scenario with or without f(R) gravity.

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Section: Analysis Of the Basic Modelmentioning

confidence: 99%

Palatini f(R) Gravity and Variants of k-/Constant Roll/Warm Inflation within Variation of Strong Coupling Scenario

et al. 2022

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“…For Higgs inflation [89],f (φ) = 1 + ξφ 2 , where ξ is the non-minimal coupling of the Higgs field. Here one can consider more complicated possibility as well by considering a non-canonical interaction between inflaton and f (R) gravity by allowing f (φ)f (R) term in the 4D effective action [92]. For the construction of effective potential we have considered this possibility.…”

mentioning

confidence: 99%

“…• Source II: Another possible source of dilaton exponential potential is coming from modified gravity theory framework such as, f (R) gravity [83][84][85][86], f (φ)f (R) gravity [89][90][91][92] and Jordan-Brans-Dicke theory [103,104] in Jordan frame, which are appearing in the Category II (1& 3) and Category III. After transforming the theory in the Einstein frame via conformal transformation one can derive dilaton exponential potential.…”

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confidence: 99%

COSMOS- $$e'$$ e ′ -soft Higgsotic attractors

Choudhury

2017

Eur. Phys. J. C

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In this work, we have developed an elegant algorithm to study the cosmological consequences from a huge class of quantum field theories (i.e. superstring theory, supergravity, extra dimensional theory, modified gravity, etc.), which are equivalently described by soft attractors in the effective field theory framework. In this description we have restricted our analysis for two scalar fields -dilaton and Higgsotic fields minimally coupled with Einstein gravity, which can be generalized for any arbitrary number of scalar field contents with generalized non-canonical and non-minimal interactions. We have explicitly used R 2 gravity, from which we have studied the attractor and non-attractor phases by exactly computing two point, three point and four point correlation functions from scalar fluctuations using the InIn (Schwinger-Keldysh) and the δN formalisms. We have also presented theoretical bounds on the amplitude, tilt and running of the primordial power spectrum, various shapes (equilateral, squeezed, folded kite or counter-collinear) of the amplitude as obtained from three and four point scalar functions, which are consistent with observed data. Also the results from two point tensor fluctuations and the field excursion formula are explicitly presented for the attractor and non-attractor phase. Further, reheating constraints, scale dependent behavior of the couplings and the dynamical solution for the dilaton and Higgsotic fields are also presented. New sets of consistency relations between two, three and four point observables are also presented, which shows significant deviation from canonical slow-roll models. Additionally, three possible theoretical proposals have presented to overcome the tachyonic instability at the time of late time acceleration. Finally, we have also provided the bulk interpretation from the three and four point scalar correlation functions for completeness.S. Choudhury: Presently working as a Visiting (Post-Doctoral) fellow at DTP, TIFR, Mumbai. a

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“…Obviously, this modification to gravity is not limited to the current epoch of Universe evolution, and it can be used to study different cosmological aspects [13][14][15][16]. Cosmological inflation within f (R) gravity has been studied extensively [17][18][19][20][21][22][23][24][25]. Finally, There are several formulations of f (R) theories known under the name of metric formalism, Palatini formalism and metric-affine formalism, the last one being the most general.…”

Section: Introductionmentioning

confidence: 99%

Natural Inflation with non minimal coupling to gravity in $R^2$ gravity under the Palatini formalism

Alhallak¹,

Aldaher²

2022

Preprint

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Natural Inflation with non-minimal coupling NMC to gravity (ξφ 2 ) is investigated in the context of an extended gravity of the form R + αR 2 . The treatment is performed in the Palatini formalism.We discuss various limitations of the model "α 1 and α 1" in light of two scenarios of inflation: a "Slow roll" and a "Constant roll".By analyzing the observational consequences of the model, our results show a significant improvement regarding compatibility between the theoretical results of this model and the experimental ones from Planck 2018, as exemplified by the tensor-to-scalar ratio and spectral index. Furthermore, a broader range of parameter space for natural inflation is now compatible with the confidence contours of Planck results. The notable effect of both NMC and αR 2 's contributions makes it a significant improvement. αR 2 gravity influences scalar-tensor ratio values. In contrast, NMC has a more significant impact on the spectral index values. Contributions to this area allow more excluded intervals to be included and are compatible with observational data.

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Inflation due to non-minimal coupling of f(R) gravity to a scalar field

Cited by 12 publications

References 27 publications

Palatini f(R) Gravity and Variants of k-/Constant Roll/Warm Inflation within Variation of Strong Coupling Scenario

Palatini f(R) Gravity and Variants of k-/Constant Roll/Warm Inflation within Variation of Strong Coupling Scenario

COSMOS- $$e'$$ e ′ -soft Higgsotic attractors

Natural Inflation with non minimal coupling to gravity in $R^2$ gravity under the Palatini formalism

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