Quantum Gravity and Inflation

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

doi:10.1007/978-3-642-33036-0_13

Cited by 17 publications

(15 citation statements)

References 85 publications

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“…The possible secular effects have been further examined by Woodard et al [10,11,12] and more recently by Polyakov et al [44,45,46], by Alvarez and Vidal [47], and also by Kitamoto and Kitazawa [34,35,48,49,50]. (See also the lecture note [51] and the references therein.) With these observations, one may worry if we cannot provide sound theoretical predictions based on the inflationary universe paradigm.…”

Section: Motivations and Overviewmentioning

confidence: 96%

Loops in inflationary correlation functions

Tanaka

Urakawa

2013

Class. Quantum Grav.

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Abstract. We review the recent progress regarding the loop corrections to the correlation functions in the inflationary universe. A naive perturbation theory predicts that loop corrections generated during inflation suffer from various infrared (IR) pathologies. Introducing an IR cutoff by hand is neither satisfactory nor enough to fix the problem of secular growth, which may ruin the predictive power of inflation models if the inflation lasts sufficiently long. We discuss the origin of the IR divergences and explore the regularity conditions of loop corrections for the adiabatic perturbation, the iso-curvature perturbation, and the tensor perturbation, in turn. These three kinds of perturbations have qualitative differences, but in discussing the IR regularity there is a feature common to all cases, which is the importance of the proper identification of observable quantities. Genuinely observable quantities should respect the gauge invariance from the view point of a local observer. Interestingly, we find that the requirement of the IR regularity restricts the allowed quantum states.

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Section: Motivations and Overviewmentioning

confidence: 96%

Loops in inflationary correlation functions

Tanaka

Urakawa

2013

Class. Quantum Grav.

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“…This relation should allow us to estimate the secular growth for an arbitrary inflationary expansion history, which is an important step in building nonlocal models to represent the quantum gravitational back-reaction on inflation [52,53,54,71]. Second, note that our transformation (17) could be used to convert the propagator of a MMC scalar into the propagator for the scalar perturbation field ζ(t, x) for an arbitrary inflationary expansion history.…”

Section: Epiloguementioning

confidence: 99%

“…A closely related issue is deciding what time best describes the putative loop counting parameter of GH 2 (t) [51]. A different sort of application concerns nonlocal modified gravity models of cosmology which are conjectured to represent quantum gravitational effects that became nonperturbatively strong during primordial inflation [52,53,54]. These quantum gravitational effects derive from secular growth in the graviton propagator which is known for de Sitter [55,56,57], but not for geometries in which ǫ(t) evolves [58].…”

Section: Introductionmentioning

confidence: 99%

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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“…The point of relevance to MOND is that these models are necessarily nonlocal [54], and that they inevitably change the force of gravity. I will close this section by commenting that this physical picture helps to justify two features phenomenological models of MOND which would be otherwise inexplicable:…”

Section: Gravitational Vacuum Polarizationmentioning

confidence: 99%

Nonlocal metric realizations of MOND

Woodard

2015

Can. J. Phys.

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I discuss relativistic extensions of MOND in which the metric couples normally to matter. I argue that MOND might be a residual effect from the vacuum polarization of infrared gravitons produced during primordial inflation. If so, MOND corrections to the gravitational field equations would be nonlocal. Nonocality also results when one constructs metric field equations which reproduce the Tully-Fisher relation, along with sufficient weak lensing. I give the full field equations for the simplest class of models, and I specialize these equations to the geometries relevant for cosmology. I conclude by sketching the direction of future studies.

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Quantum Gravity and Inflation

Cited by 17 publications

References 85 publications

Loops in inflationary correlation functions

Loops in inflationary correlation functions

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

Nonlocal metric realizations of MOND

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