In-in and δ<i>N</i>calculations of the bispectrum from non-attractor single-field inflation

Chen, Xingang; Firouzjahi, Hassan; Komatsu, Eiichiro; Namjoo, Mohammad Hossein; Sasaki, Misao

doi:10.1088/1475-7516/2013/12/039

Cited by 67 publications

(116 citation statements)

References 81 publications

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“…Further using δN formalism, the CMB dipolar asymmetry parameter for single field inflationary framework can be expressed as [54]: . In this paper I have obtained different result as the non-minimal Kähler interactions within N = 1 SUGRA effective theory setup which is completely different compared to the case studied in [46].…”

Section: Jhep04(2014)105mentioning

confidence: 77%

“…(4.8) for a fixed set of W k , I have obtained N as a implicit function of φ and W k . Then the δN formula can be obtained by [46]:…”

Section: δN At the Final Hypersurfacementioning

confidence: 99%

“…Then the simplest choice is to take the initial time to be infinitesimally close to t = t * . Now perturbing the number of e-folds N up to the second order at the epoch t = t * , I get [46]: to the leading order contributions. By taking the derivatives of both sides of eq.…”

Section: δN At the Final Hypersurfacementioning

confidence: 99%

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Constraining $ \mathcal{N} $ = 1 supergravity inflation with non-minimal Kähler operators using δN formalism

Choudhury

2014

J. High Energ. Phys.

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In this paper I provide a general framework based on δN formalism to study the features of unavoidable higher dimensional non-renormalizable Kähler operators for N = 1 supergravity (SUGRA) during primordial inflation from the combined constraint on nonGaussianity, sound speed and CMB dipolar asymmetry as obtained from the recent Planck data. In particular I study the nonlinear evolution of cosmological perturbations on large scales which enables us to compute the curvature perturbation, ζ, without solving the exact perturbed field equations. Further I compute the non-Gaussian parameters f N L , τ N L and g N L for local type of non-Gaussianities and CMB dipolar asymmetry parameter, A CM B , using the δN formalism for a generic class of sub-Planckian models induced by the Hubbleinduced corrections for a minimal supersymmetric D-flat direction where inflation occurs at the point of inflection within the visible sector. Hence by using multi parameter scan I constrain the non-minimal couplings appearing in non-renormalizable Kähler operators within, O(1), for the speed of sound, 0.02 ≤ c s ≤ 1, and tensor to scalar, 10 −22 ≤ r ⋆ ≤ 0.12. Finally applying all of these constraints I will fix the lower as well as the upper bound of the non-Gaussian parameters within,and O(17.4 − 34.7) ≤ g N L ≤ 648.2, and CMB dipolar asymmetry parameter within the range, 0.05 ≤ A CM B ≤ 0.09.

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Section: Jhep04(2014)105mentioning

confidence: 77%

“…(4.8) for a fixed set of W k , I have obtained N as a implicit function of φ and W k . Then the δN formula can be obtained by [46]:…”

Section: δN At the Final Hypersurfacementioning

confidence: 99%

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Constraining $ \mathcal{N} $ = 1 supergravity inflation with non-minimal Kähler operators using δN formalism

Choudhury

2014

J. High Energ. Phys.

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“…A non-zero contribution originates from the Q dσ term, in the presence of a correlation between isocurvature and curvature modes, which is the case for QsF inflation. Schematically this term gives 19) where the first term in the first line on the r.h.s. of Eq.…”

Section: Consistency Conditions For Inflation With Extra Fieldsmentioning

confidence: 99%

Imprints of massive primordial fields on large-scale structure

Dimastrogiovanni

Fasiello

Kamionkowski

2016

J. Cosmol. Astropart. Phys.

107

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Abstract. Attention has focussed recently on models of inflation that involve a second or more fields with a mass near the inflationary Hubble parameter H, as may occur in supersymmetric theories if the supersymmetry-breaking scale is not far from H. Quasi-single-field (QsF) inflation is a relatively simple family of phenomenological models that serve as a proxy for theories with additional fields with masses m ∼ H. Since QsF inflation involves fields in addition to the inflaton, the consistency conditions between correlations that arise in singleclock inflation are not necessarily satisfied. As a result, correlation functions in the squeezed limit may be larger than in single-field inflation. Scalar non-Gaussianities mediated by the massive isocurvature field in QsF have been shown to be potentially observable. These are especially interesting since they would convey information about the mass of the isocurvature field. Here we consider non-Gaussian correlators involving tensor modes and their observational signatures. A physical correlation between a (long-wavelength) tensor mode and two scalar modes (tss), for instance, may give rise to local departures from statistical isotropy or, in other words, a non-trivial four-point function. The presence of the tensor mode may moreover be inferred geometrically from the shape dependence of the four-point function. We compute tss and stt (one soft curvature mode and two hard tensors) bispectra in QsF inflation, identifying the conditions necessary for these to "violate" the consistency relations. We find that while consistency conditions are violated by stt correlations, they are preserved by the tss in the minimal QsF model. Our study of primordial correlators which include gravitons in seeking imprints of additional fields with masses m ∼ H during inflation can be seen as complementary to the recent "cosmological collider physics" proposal.arXiv:1504.05993v3 [astro-ph.CO]

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“…In this regard, the method of calculating δN is similar to the analysis of [56]. However, the effects of the background evolution of the VSL cosmology upon curvature perturbations are analogous to those occurring in the study of the matter bounce cosmology [57,58], where there is no quasi de Sitter expansion.…”

Section: Primordial Perturbations and Non-gaussianities In The Vsl Comentioning

confidence: 99%

Variable speed of light cosmology, primordial fluctuations and gravitational waves

Moffat

2016

Eur. Phys. J. C

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A variable speed of light (VSL) cosmology is described in which the causal mechanism of generating primordial perturbations is achieved by varying the speed of light in a primordial epoch. This yields an alternative to inflation for explaining the formation of the cosmic microwave background (CMB) and the large scale structure (LSS) of the universe. The initial value horizon and flatness problems in cosmology are solved. The model predicts primordial scalar and tensor fluctuation spectral indices n s = 0.96 and n t = −0.04, respectively. We make use of the δN formalism to identify signatures of primordial nonlinear fluctuations, and this allows the VSL model to be distinguished from inflationary models. In particular, we find that the parameter f NL = 5 in the variable speed of light cosmology. The value of the parameter g NL evolves during the primordial era and shows a running behavior.

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In-in and δNcalculations of the bispectrum from non-attractor single-field inflation

Cited by 67 publications

References 81 publications

Constraining $ \mathcal{N} $ = 1 supergravity inflation with non-minimal Kähler operators using δN formalism

Constraining $ \mathcal{N} $ = 1 supergravity inflation with non-minimal Kähler operators using δN formalism

Imprints of massive primordial fields on large-scale structure

Variable speed of light cosmology, primordial fluctuations and gravitational waves

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