Computing the primordial power spectra directly

Romania, Maria G.; Tsamis, N. C.; Woodard, R. P.

doi:10.1088/1475-7516/2012/08/029

Cited by 23 publications

(37 citation statements)

References 38 publications

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“…holds at all time. Following [59,60], one can then easily deduce a non-linear evolution equation for the power spectrum P ζ k ≡ k 3 /(2π 2 )|ζ k | 2 itself, which reads, in e-fold time:…”

Section: Imaginary Speed Of Soundmentioning

confidence: 99%

Primordial fluctuations and non-Gaussianities in sidetracked inflation

García-Sáenz

Renaux‐Petel

Ronayne

2018

J. Cosmol. Astropart. Phys.

179

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Heavy scalar fields can undergo an instability during inflation as a result of their kinetic couplings with the inflaton. This is known as the geometrical destabilization of inflation, as it relies on the effect of the negative curvature of the field-space manifold overcoming the stabilizing force of the potential. This instability can drive the system away from its original path in field space into a new inflationary attractor, a scenario that we dub sidetracked inflation. We study this second phase and its observable consequences in several classes of two-field models. We show that cosmological fluctuations exhibit varied behaviours depending on the potential and the field space geometry, and that they can be captured by single-field effective theories with either a modified dispersion relation, a reduced speed of sound, or an imaginary one -the latter case describing a transient tachyonic growth of the fluctuations. We also numerically calculate the bispectrum with the transport approach, finding large non-Gaussianities of equilateral and orthogonal shapes. In the hyperbolic geometry the potentials of our models present a pole at the boundary of the Poincaré disk and we discuss their relationships with α-attractors.

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Section: Imaginary Speed Of Soundmentioning

confidence: 99%

Primordial fluctuations and non-Gaussianities in sidetracked inflation

García-Sáenz

Renaux‐Petel

Ronayne

2018

J. Cosmol. Astropart. Phys.

179

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“…It begins by reviewing the derivation of an evolution equation for M(t, k) ≡ |u(t, k)| 2 [44,45]. We then factor out the main effect by writing…”

Section: Our Evolution Equationmentioning

confidence: 99%

“…We have instead focussed on predicting how the amplitudes depend upon the inflationary expansion history a(t). Our analysis is based on earlier work in which nonlinear equations for the two amplitudes were derived [44,45].…”

Section: Epiloguementioning

confidence: 99%

“…Of course we do not have MMC scalar propagator for arbitrary a(t) but perhaps the transformation could be used to derive relations between loops involving gravitons and loops involving ζ. Finally, our technique for passing from the oscillatory mode functions to their norm-squared [44,45] can be applied for any perturbations whose mode functions obey second order equations. It would be interesting to see what it gives for Higgs inflation and for f (R) models of inflation.…”

Section: Epiloguementioning

confidence: 99%

“…Our goal is to instead devise a good analytic prediction for the tree order power spectra from any scalar potential model. We will elaborate a numerical scheme developed previously [44,45], both to make the scheme even more efficient and to motivate what should be an excellent analytic approximation for the power spectra. One fascinating feature of this formalism is that the tensor power spectrum can easily be converted into its scalar cousin, so one need only work with the simpler tensor result.…”

Section: Introductionmentioning

confidence: 99%

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Precision predictions for the primordial power spectra of scalar potential models of inflation

2016

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We exploit a new numerical technique for evaluating the tree order contributions to the primordial scalar and tensor power spectra for scalar potential models of inflation. Among other things we use the formalism to develop a good analytic approximation which goes beyond generalized slow roll expansions in that (1) it is not contaminated by the physically irrelevant phase, (2) its 0th order term is exact for constant first slow roll parameter, and (3) the correction is multiplicative rather than additive. These features allow our formalism to capture at first order, effects which are higher order in other expansions. Although this accuracy is not necessary to compare current data with any specific model, our method has a number of applications owing to the simpler representation it provides for the connection between the power spectra and the expansion history of a general model.

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Explosive particle production in non-commutative inflation

Perrier

Durrer

Rinaldi

2013

J. High Energ. Phys.

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We consider a model of inflation which has recently been proposed in the literature and where inflation is induced by corrections to the energy density coming from the non-commutativity of spacetime. We show that the very rapid inflationary expansion typical of this model is responsible for a burst of particle production which ends inflation and leads to a radiation-dominated phase. We analytically estimate the energy density of these particles and we confront the results with more precise numerical calculations. We estimate the number of inflationary e-folds before the back-reaction of the radiation energy density overcomes the non-commutative effects and terminates inflation naturally.arXiv:1210.5373v2 [gr-qc]

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Computing the primordial power spectra directly

Cited by 23 publications

References 38 publications

Primordial fluctuations and non-Gaussianities in sidetracked inflation

Primordial fluctuations and non-Gaussianities in sidetracked inflation

Precision predictions for the primordial power spectra of scalar potential models of inflation

Explosive particle production in non-commutative inflation

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