Primordial features due to a step in the inflaton potential

Hazra, Dhiraj Kumar; Aich, Moumita; Jain, Rajeev Kumar; Sriramkumar, L.; Souradeep, T.

doi:10.1088/1475-7516/2010/10/008

Cited by 115 publications

(144 citation statements)

References 51 publications

(90 reference statements)

Supporting

Mentioning

143

Contrasting

Order By: Relevance

“…Interestingly, these transient violations of slow roll also allow for detectably large local nonGaussianities [167] (69), although these will require the implementation of estimators that are sensitive to scale dependent local nonGaussianity, a topic which we will return to in the next section. The authors of [141] furthermore considered interrupted slow roll as a mechanism through which to suppress primordial power at large angular scales, which as a corollary also generates oscillatory features that might account for certain 'outliers' in the angular power spectrum [168,169] xlii . Within the context of standard, uninterrupted inflation (where remains small and uniformly bounded throughout) one can envisage situations where higher order terms in the Hubble hierarchy (e.g.…”

Section: Effective Potential Modulations and Phase Transitionsmentioning

confidence: 99%

Features and new physical scales in primordial observables: Theory and observation

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

197

233

View full text Add to dashboard Cite

June 22, 20152 All cosmological observations to date are consistent with adiabatic, Gaussian and nearly scale invariant initial conditions. These findings provide strong evidence for a particular symmetry breaking pattern in the very early universe (with a close to vanishing order parameter, ), widely accepted as conforming to the predictions of the simplest realizations of the inflationary paradigm. However, given that our observations are only privy to perturbations, in inferring something about the background that gave rise to them, it should be clear that many different underlying constructions project onto the same set of cosmological observables. Features in the primordial correlation functions, if present, would offer a unique and discriminating window onto the parent theory in which the mechanism that generated the initial conditions is embedded. In certain contexts, simple linear response theory allows us to infer new characteristic scales from the presence of features that can break the aforementioned degeneracies among different background models, and in some cases can even offer a limited spectroscopy of the heavier degrees of freedom that couple to the inflaton. In this review, we offer a pedagogical survey of the diverse, theoretically well grounded mechanisms which can imprint features into primordial correlation functions in addition to reviewing the techniques one can employ to probe observations. These observations include cosmic microwave background anisotropies and spectral distortions as well as the matter two and three point functions as inferred from large-scale structure and potentially, 21 cm surveys.

show abstract

Section: Effective Potential Modulations and Phase Transitionsmentioning

confidence: 99%

Features and new physical scales in primordial observables: Theory and observation

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

197

233

View full text Add to dashboard Cite

show abstract

“…The step results in a brief period of fast roll, which leads to the oscillations in the scalar power spectrum. For instance, if a step is introduced in the conventional quadratic potential, the complete potential can be written as 2) where, evidently, φ 0 , α and ∆φ represent the location, the height and the width of the step, respectively [47,49,50]. Spectra with repeated modulations extending over a wide range of scales can be generated by potentials which contain oscillatory terms such as in the axion monodromy model [53][54][55].…”

Section: Numerical Verification Of the Relation During Deviations Fromentioning

confidence: 99%

On the scalar consistency relation away from slow roll

Vijayakumar

Hazra

Sriramkumar

2015

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

Abstract. As is well known, the non-Gaussianity parameter f NL , which is often used to characterize the amplitude of the scalar bi-spectrum, can be expressed completely in terms of the scalar spectral index n s in the squeezed limit, a relation that is referred to as the consistency condition. This relation, while it is largely discussed in the context of slow roll inflation, is actually expected to hold in any single field model of inflation, irrespective of the dynamics of the underlying model, provided inflation occurs on the attractor at late times. In this work, we explicitly examine the validity of the consistency relation, analytically as well as numerically, away from slow roll. Analytically, we first arrive at the relation in the simple case of power law inflation. We also consider the non-trivial example of the Starobinsky model involving a linear potential with a sudden change in its slope (which leads to a brief period of fast roll), and establish the condition completely analytically. We then numerically examine the validity of the consistency relation in three inflationary models that lead to the following features in the scalar power spectrum due to departures from slow roll: (i) a sharp cut off at large scales, (ii) a burst of oscillations over an intermediate range of scales, and (iii) small, but repeated, modulations extending over a wide range of scales. It is important to note that it is exactly such spectra that have been found to lead to an improved fit to the CMB data, when compared to the more standard power law primordial spectra, by the Planck team. We evaluate the scalar bi-spectrum for an arbitrary triangular configuration of the wavenumbers in these inflationary models and explicitly illustrate that, in the squeezed limit, the consistency condition is indeed satisfied even in situations consisting of strong deviations from slow roll. We conclude with a brief discussion of the results.

show abstract

“…In spite of this, models that accounts for the localised 'features' in the primordial power spectrum have been matter of study, since could provide a better fit to the data with respect to the smooth power-law (Ref. [3][4][5][6][7][8][9][10][11] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Cosmic microwave background and large scale structure constraints on primordial inflation

Benetti¹,

Alcaniz²

2017

The Fourteenth Marcel Grossmann Meeting

View full text Add to dashboard Cite

In this work we present preliminary results of cosmological constraints on a class of inflationary models with departures from the nearly-scale-invariant power law spectrum. We combine the Cosmic Microwave Background (CMB) data from the Planck Collaboration with measurements of the galaxy clustering obtained from the eleventh data release of the Sloan Digital Sky Survey (SDSS DR11) to investigate observable signatures of this class of models in the CMB anisotropy and the matter power spectra. In order to discuss the observational viability of such scenarios we also perform a Bayesian comparison with the standard, nearly-scale-invariant power law spectrum model.

show abstract

Primordial features due to a step in the inflaton potential

Cited by 115 publications

References 51 publications

Features and new physical scales in primordial observables: Theory and observation

Features and new physical scales in primordial observables: Theory and observation

On the scalar consistency relation away from slow roll

Cosmic microwave background and large scale structure constraints on primordial inflation

Contact Info

Product

Resources

About