Starobinsky-like inflation in dilaton-brane cosmology

Ellis, John; Mavromatos, Nick E.; Nanopoulos, Dimitri V.

doi:10.1016/j.physletb.2014.04.014

Cited by 34 publications

(90 citation statements)

References 40 publications

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“…Specifically, by introducing one additional parameter, the Starobinsky model can interpolate to quadratic or natural inflation [44][45][46][47][48][49][50][51][52][53][54]. The problem of trans-Planckian field excursion has been carefully considered in quadratic and natural inflation, while it usually is ignored for Starobinsky-like inflation, since the tensor-to-scalar ratio is lower than the Lyth bound r ∼ 0.01.…”

Section: Jhep10(2015)138mentioning

confidence: 99%

Helical phase inflation via non-geometric flux compactifications: from natural to starobinsky-like inflation

Nanopoulos

2015

J. High Energ. Phys.

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We show that a new class of helical phase inflation models can be simply realized in minimal supergravity, wherein the inflaton is the phase component of a complex field and its potential admits a deformed helicoid structure. We find a new unique complex-valued index χ that characterizes almost the entire region of the n s − r plane favored by new Planck observations. Continuously varying the index χ, predictions interpolate from quadratic/natural inflation parameterized by a phase/axion decay constant to Starobinsky-like inflation parameterized by the α-parameter. We demonstrate that the simple supergravity construction realizing Starobinsky-like inflation can be obtained from a more microscopic model by integrating out heavy fields, and that the flat phase direction for slow-roll inflation is protected by a mildly broken global U(1) symmetry. We study the geometrical origin of the index χ, and find that it corresponds to a linear constraint relating Kähler moduli. We argue that such a linear constraint is a natural result of moduli stabilization in Type II orientifold compactifications on Calabi-Yau threefolds with geometric and non-geometric fluxes. Possible choices for the index χ are discrete points on the complex plane that relate to the distribution of supersymmetric Minkowski vacua on JHEP10 (2015)138 moduli space. More precise observations of the inflationary epoch in the future may provide a better estimation of the index χ. Since χ is determined by the fluxes and vacuum expectation values of complex structure moduli, such observations would characterize the geometry of the internal space as well.

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Section: Jhep10(2015)138mentioning

confidence: 99%

Helical phase inflation via non-geometric flux compactifications: from natural to starobinsky-like inflation

Nanopoulos

2015

J. High Energ. Phys.

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“…The reconstruction procedure for cosmological models with non-minimally coupled scalar fields evolving on a flat FLRW background and in different MGTs was studied in [6][7][8][9][10][11][12]. In this work, we elaborated a reconstruction method for the massive gravity theory which admits an effective offdiagonal interpretation in GR and f -modified gravity with a cyclic and an ekpyrotic universe solution.…”

Section: Discussionmentioning

confidence: 99%

“…[36][37][38][39][40][41][42][43][44]. That anholonomic frame deformation method (AFDM) can be applied for the decoupling, and for constructing solutions of the MGT field equations (5) with any effective source parameterized in the form (12); see details in Refs. [36][37][38][39][40][41][42][43][44]).…”

Section: Generating Off-diagonal Cosmological Solutionsmentioning

confidence: 99%

“…Another alternative came from the idea that the graviton may have a nontrivial mass as was proposed by Fierz and Pauli [1]. For recent reviews and related f (R) modifications and cosmological models, in general, with non-minimal coupling and dilaton-brane cosmology, local anisotropies and/or effective modeling of massive gravity, see, respectively, [6][7][8][9][10][11][12] and [13][14][15][16][17][18]. The modern version of a ghost-free (bimetric) massive gravity theory was made in a series of papers (recent reviews can be found in [19]): developing generic nonlinear versions of the FierzPauli theory, the so-called vDVZ discontinuity problem was solved via the Vainshtein mechanism [20][21][22] (avoiding the discontinuity by going beyond the linear theory).…”

Section: Introductionmentioning

confidence: 99%

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Equivalent off-diagonal cosmological models and ekpyrotic scenarios in $$f(R)$$ f ( R ) -modified, massive, and einstein gravity

Vacaru

2015

Eur. Phys. J. C

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We reinvestigate how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates can be constructed in massive and fmodified gravity using the anholonomic frame deformation method. New classes of locally anisotropic and (in-) homogeneous cosmological metrics are constructed with open and closed spatial geometries. By resorting to such solutions, we show that they describe the late time acceleration due to effective cosmological terms induced by nonlinear off-diagonal interactions, possible modifications of the gravitational action and graviton mass. The cosmological metrics and related Stückelberg fields are constructed in explicit form up to nonholonomic frame transforms of the Friedmann-Lamaître-Robertson-Walker (FLRW) coordinates. The solutions include matter, graviton mass, and other effective sources modeling nonlinear gravitational and matter field interactions with polarization of physical constants and deformations of metrics, which may explain dark energy and dark matter effects. However, we argue that it is not always necessary to modify gravity if we consider the effective generalized Einstein equations with nontrivial vacuum and/or non-minimal coupling with matter. Indeed, we state certain conditions when such configurations mimic interesting solutions in general relativity and modifications, for instance, when we can extract the general Painlevé-Gullstrand and FLRW metrics. In a more general context, we elaborate on a reconstruction procedure for off-diagonal cosmological solutions which describe cyclic and ekpyrotic universes. Finally, open issues and further perspectives are discussed.Associated visiting research affiliation

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“…This implies ψ ≫ 1 or, equivalently, df /dR ≫ 1, therefore a regime where the R n -term is dominant. Moreover, the Starobinsky-like inflation model may also emerge from dilaton dynamics in brane cosmology scenarios based on string theory [17]. Models based on (1.2) have been also studied in the context of bouncing cosmology (see, for example, [18]).…”

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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Starobinsky-like inflation in dilaton-brane cosmology

Cited by 34 publications

References 40 publications

Helical phase inflation via non-geometric flux compactifications: from natural to starobinsky-like inflation

Helical phase inflation via non-geometric flux compactifications: from natural to starobinsky-like inflation

Equivalent off-diagonal cosmological models and ekpyrotic scenarios in $$f(R)$$ f ( R ) -modified, massive, and einstein gravity

Cosmological evolution of thermal relic particles inf(R)gravity

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