Running of scalar spectral index in multi-field inflation

Gong, Jinn‐Ouk

doi:10.1088/1475-7516/2015/05/041

Cited by 5 publications

(2 citation statements)

References 49 publications

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“…Even in the absence of a detected deviation from the concordance model, upper limits on various observables greatly help to discriminate among early-universe models. Particularly interesting observables in this regard include non-adiabaticity [2], running of the scalar spectral index [3][4][5][6], primordial tensor fluctuations [7][8][9][10], and non-Gaussianity [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

CMBB-mode non-Gaussianity

et al. 2016

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We study the degree to which the cosmic microwave background (CMB) can be used to constrain primordial non-Gaussianity involving one tensor and two scalar fluctuations, focusing on the correlation of one polarization B mode with two temperature modes. In the simplest models of inflation, the tensor-scalar-scalar primordial bispectrum is non-vanishing and is of the same order in slow-roll parameters as the scalar-scalar-scalar bispectrum. We calculate the BT T correlation arising from a primordial tensor-scalar-scalar bispectrum, and show that constraints from an experiment like CMB-Stage IV using this observable are more than an order of magnitude better than those on the same primordial coupling obtained from temperature measurements alone. We argue that B-mode non-Gaussianity opens up an as-yet-unexplored window into the early Universe, demonstrating that significant information on primordial physics remains to be harvested from CMB anisotropies.

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Section: Introductionmentioning

confidence: 99%

CMBB-mode non-Gaussianity

et al. 2016

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“…One of the most important physical observables in inflationary cosmology is the power spectrum of primordial density perturbations. In fact, for any viable theory of inflation, before non-Gaussianity/trispectrum [11][12][13][14][15][16], tensor-to-scalar ratio [17][18][19], loop corrections [20,21], and spectral index and its running [22,23]quantities that have occupied a significant part of the current millennium's researches in inflationary cosmologythe power spectrum in its most basic form has to be calculated first. As such, the need for a logically consistent expression for the power spectrum based on solid physical and mathematical grounds, cannot be overemphasized.…”

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confidence: 99%

Adiabatic regularization of the power spectrum in nonminimally coupled general single-field inflation

Alinea

Kubota

2018

Phys. Rev. D

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We perform adiabatic regularization of power spectrum in nonminimally coupled general singlefield inflation with varying speed of sound. The subtraction is performed within the framework of earlier study by Urakawa and Starobinsky dealing with the canonical inflation. Inspired by Fakir and Unruh's model on nonminimally coupled chaotic inflation, we find upon imposing near scaleinvariant condition, that the subtraction term exponentially decays with the number of e-folds. As in the result for the canonical inflation, the regularized power spectrum tends to the "bare" power spectrum as the Universe expands during (and even after) inflation. This work justifies the use of the "bare" power spectrum in standard calculation in the most general context of slow-roll single-field inflation involving non-minimal coupling and varying speed of sound.

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Nonminimally assisted inflation: a general analysis

Hyun

Kim

Kodama

et al. 2023

J. Cosmol. Astropart. Phys.

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The effects of a scalar field, known as the “assistant field,” which nonminimally couples to gravity, on single-field inflationary models are studied. The analysis provides analytical expressions for inflationary observables such as the spectral index (ns ), the tensor-to-scalar ratio (r), and the local-type nonlinearity parameter (f NL (local)). The presence of the assistant field leads to a lowering of ns and r in most of the parameter space, compared to the original predictions. In some cases, ns may increase due to the assistant field. This revives compatibility between ruled-out single-field models and the latest observations by Planck-BICEP/Keck. The results are demonstrated using three example models: loop inflation, power-law inflation, and hybrid inflation.

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Running of scalar spectral index in multi-field inflation

Cited by 5 publications

References 49 publications

CMBB-mode non-Gaussianity

CMBB-mode non-Gaussianity

Adiabatic regularization of the power spectrum in nonminimally coupled general single-field inflation

Nonminimally assisted inflation: a general analysis

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