Oscillations in the inflaton potential: Complete numerical treatment and comparison with the recent and forthcoming CMB datasets

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

doi:10.1103/physrevd.87.083526

Cited by 68 publications

(88 citation statements)

References 71 publications

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“…11 The net effect of this process are oscillatory features in the power spectrum, with the frequency of the oscillation depending on how brief was the overall turn. While current observational constraints on features are still poor [5,[80][81][82][83][84][85][86][87][88][89], future data will certainly put strong constraints on primordial features, therefore improving our understanding of the role of UV-physics on the very early universe.…”

Section: Discussionmentioning

confidence: 99%

On the importance of heavy fields during inflation

Céspedes

Atal

Palma

2012

J. Cosmol. Astropart. Phys.

140

207

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We study the dynamics of two-field models of inflation characterized by a hierarchy of masses between curvature and isocurvature modes. When the hierarchy is large, a low energy effective field theory (EFT) exists in which only curvature modes participate in the dynamics of perturbations. In this EFT heavy fields continue to have a significant role in the low energy dynamics, as their interaction with curvature modes reduces their speed of sound whenever the multi-field trajectory is subject to a sharp turn in target space. Here we analyze under which general conditions this EFT remains a reliable description for the linear evolution of curvature modes. We find that the main condition consists on demanding that the rate of change of the turn's angular velocity stays suppressed with respect to the masses of heavy modes. This adiabaticity condition allows the EFT to accurately describe a large variety of situations in which the multi-field trajectory is subject to sharp turns. To test this, we analyze several models with turns and show that, indeed, the power spectra obtained for both the original two-field theory and its single-field EFT are identical when the adiabaticity condition is satisfied. In particular, when turns are sharp and sudden, they are found to generate large features in the power spectrum, accurately reproduced by the EFT.arXiv:1201.4848v3 [hep-th]

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Section: Discussionmentioning

confidence: 99%

On the importance of heavy fields during inflation

Céspedes

Atal

Palma

2012

J. Cosmol. Astropart. Phys.

140

207

View full text Add to dashboard Cite

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“…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]. The potential in such a case is given by…”

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.

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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.

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“…In addition, one would like to map out the more detailed, but model-dependent signatures from the residual oscillations in the potential (1.1) [25,26] generated by the sectors of the physics that respect the underlying periodicity φ → φ + 2πf . The search for such oscillations -which has so far led to constraints [88][89][90][91][92][93][94] -may be affected by the theoretical spectrum of possible values of p, and by the possibility of dynamical relaxation of the period f and of the model-dependent amplitude Λ 4 of the oscillations during inflation. All this provides ample motivation for further study.…”

Section: Jhep09(2014)123mentioning

confidence: 99%

The powers of monodromy

McAllister

Silverstein

Westphal

et al. 2014

J. High Energ. Phys.

242

339

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Flux couplings to string theory axions yield super-Planckian field ranges along which the axion potential energy grows. At the same time, other aspects of the physics remain essentially unchanged along these large displacements, respecting a discrete shift symmetry with a sub-Planckian period. After a general overview of this monodromy effect and its application to large-field inflation, we present new classes of specific models of monodromy inflation, with monomial potentials µ 4−p φ p . A key simplification in these models is that the inflaton potential energy plays a leading role in moduli stabilization during inflation. The resulting inflaton-dependent shifts in the moduli fields lead to an effective flattening of the inflaton potential, i.e. a reduction of the exponent from a fiducial value p 0 to p < p 0 . We focus on examples arising in compactifications of type IIB string theory on products of tori or Riemann surfaces, where the inflaton descends from the NS-NS two-form potential B 2 , with monodromy induced by a coupling to the R-R field strength F 1 . In this setting we exhibit models with p = 2/3, 4/3, 2, and 3, corresponding to predictions for the tensor-to-scalar ratio of r ≈ 0.04, 0.09, 0.13, and 0.2, respectively. Using mirror symmetry, we also motivate a second class of examples with the role of the axions played by the real parts of complex structure moduli, with fluxes inducing monodromy.

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Oscillations in the inflaton potential: Complete numerical treatment and comparison with the recent and forthcoming CMB datasets

Cited by 68 publications

References 71 publications

On the importance of heavy fields during inflation

On the importance of heavy fields during inflation

On the scalar consistency relation away from slow roll

The powers of monodromy

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