Non-Gaussianity consistency relations, initial states and back-reaction

Kundu, Sandipan

doi:10.1088/1475-7516/2014/04/016

Cited by 47 publications

(60 citation statements)

References 85 publications

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“…Having a power spectrum in the squeezed k 3 k 1 ∼ k 2 limit suffices to obtain the bispectrum. According to [28], the three point function of the scalar perturbation in the squeezed limit for α-vacua is given by…”

Section: φ(T) Andḡ μν (T) φ(T X) =φ(T) + δφ(T X)mentioning

confidence: 99%

Higgs inflation and general initial conditions

Zeynizadeh

Akbarieh

2015

Eur. Phys. J. C

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A Higgs field of particle physics can play the role of the inflaton in the early universe if it is non-minimally coupled to gravity. The Higgs inflation scenario predicts a small tensor to scalar ratio: r 0.003. Although this value is consistent with the upper bound r < 0.12 given by the BICEP2/Keck Array and Planck data, it is not at their maximum likelihood point: r 0.05. Inflationary observables depend not only on the inflationary models, but they also depend on the initial conditions of inflation. Changing the initial state of inflation can improve the value of r . In this work, we study the Higgs inflation model under general initial conditions and show that there is a subset of these general initial conditions which leads to enhancement of r . Then we show that this region of parameter space is consistent with a non-Gaussianity bound.

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Section: φ(T) Andḡ μν (T) φ(T X) =φ(T) + δφ(T X)mentioning

confidence: 99%

Higgs inflation and general initial conditions

Zeynizadeh

Akbarieh

2015

Eur. Phys. J. C

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“…Thus, the BD vacuum is usually regarded as the initial state of the primordial perturbations. The effects of non-BD initial states on the primordial perturbation has been discussed in, e.g., Refs., [77], [78], [79], [80], [81], [82], [83], [84]. Here, the Bogoliubov coefficients…”

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confidence: 99%

Preinflationary primordial perturbations

2015

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The large-scale power deficit in the cosmic microwave background fluctuations might be relevant with the physics of pre-inflation, a bounce, or a superinflationary phase preceding slow-roll inflation, which can provide a singular-free realization of inflation. We investigate the primordial perturbations from such pre-inflationary evolutions, which generally may consist of multiple phases with different background dynamics, and give a universal formula for the power spectrum of primordial perturbations in terms of the recursive Bogoliubov coefficients. We also apply our formula to corresponding cases and show how the intensity of large-scale power suppression is affected by the pre-inflationary physics.

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“…They have pointed out that this gauge can not be applied for a general f (R, φ) gravity including the non linear terms in curvature. 6 Here we concentrate on a general f (R, φ) theory. Looking at (37), we choose a different gauge defined by: 7…”

Section: Mukhanov-sasaki Equationmentioning

confidence: 99%

On the initial conditions of scalar and tensor fluctuations in $$f(R,\phi )$$ f ( R , ϕ ) gravity

Cheraghchi

Shojai

2018

Eur. Phys. J. C

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We have considered the perturbation equations governing the growth of fluctuations during inflation in generalized scalar tensor theory f (R, φ). We have found that the scalar metric perturbations at very early times are negligible compared to the scalar field perturbation, just like general relativity. At sufficiently early times, when the physical momentum of perturbation mode, q/a is much larger than the Hubble parameter H , i.e. q/a H , we have obtained the metric and scalar field perturbation in the form of WKB solutions up to an undetermined coefficient. Then we have quantized the scalar fluctuations and expanded the metric and the scalar field perturbations with the help of annihilation and creation operators of the scalar field perturbation. The standard commutation relations of annihilation and creation operators fix the unknown coefficient. Going over to the gauge invariant quantities which are conserved beyond the horizon, we have obtained the initial condition of the generalized Mukhanov-Sasaki equation. Then a similar procedure is performed for the case of tensor metric perturbation. As an example of the generalized Mukhanov-Sasaki equation and its initial condition, we have proposed a power-law functional form as f (R, φ) = f 0 R m φ n and obtained an exact inflationary solution. In this background, then we have discussed how the scalar and tensor fluctuations grow.

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Non-Gaussianity consistency relations, initial states and back-reaction

Cited by 47 publications

References 85 publications

Higgs inflation and general initial conditions

Higgs inflation and general initial conditions

Preinflationary primordial perturbations

On the initial conditions of scalar and tensor fluctuations in $$f(R,\phi )$$ f ( R , ϕ ) gravity

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