Primordial cosmic fluctuations for variable gravity

Wetterich, C.

doi:10.1088/1475-7516/2016/05/041

Cited by 23 publications

(37 citation statements)

References 85 publications

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“…This quantitative modification does not change any of our qualitative findings. For the effective action (31) the inverse graviton propagator becomes [52]…”

Section: Flow On Cosmological Backgroundsmentioning

confidence: 99%

Graviton fluctuations erase the cosmological constant

Wetterich

2017

Physics Letters B

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Graviton fluctuations induce strong non-perturbative infrared renormalization effects for the cosmological constant. The functional renormalization flow drives a positive cosmological constant towards zero, solving the cosmological constant problem without the need to tune parameters. We propose a simple computation of the graviton contribution to the flow of the effective potential for scalar fields. Within variable gravity we find that the potential increases asymptotically at most quadratically with the scalar field. With effective Planck mass proportional to the scalar field, the solutions of the derived cosmological equations lead to an asymptotically vanishing cosmological "constant" in the infinite future, providing for dynamical dark energy in the present cosmological epoch. Beyond a solution of the cosmological constant problem, our simplified computation also entails a sizeable positive graviton-induced anomalous dimension for the quartic Higgs coupling in the ultraviolet regime, substantiating the successful prediction of the Higgs boson mass within the asymptotic safety scenario for quantum gravity.Comment: extended discussion, new references, 14 pages, 2 figure

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“…This quantitative modification does not change any of our qualitative findings. For the effective action (31) the inverse graviton propagator becomes [52]…”

Section: Flow On Cosmological Backgroundsmentioning

confidence: 99%

Graviton fluctuations erase the cosmological constant

Wetterich

2017

Physics Letters B

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“…During inflation, 1/(aH Per ) nearly coincide with 1/(aH), which suggests that the shape of perturbation spectrum is mainly set up by the background evolution. However, during slow expansion, 1/(aH Per ) ≪ 1/(aH), so the background is irrelevant with the origin of primordial perturbation, as clarified recently also by Wetterich in [31].…”

Section: Overview Of Slow Expansion Scenariomentioning

confidence: 89%

“…Recently, Wetterich has clarified how the scale-invariant primordial perturbations arise in flat Minkowski space [31], as in [13] base on the scenario with (1.1). Here, we will focus on that with (1.2), which helps to better highlight the physics of primordial perturbations and the role of conformal frames.…”

Section: Jhep03(2016)134mentioning

confidence: 99%

The slow expansion with nonminimal derivative coupling and its conformal dual

Cai

Piao

2016

J. High Energ. Phys.

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We show that the primordial gravitational wave with scale-invariant spectrum might emerge from a nearly Minkowski space, in which the gravity is asymptotic-past free. We illustrate it with a model, in which the derivative of background scalar field nonminimally couples to gravity. We also show that since here the tensor perturbation is dominated by its growing mode, mathematically our slowly expanding background is conformally dual to the matter contraction, but there is no the anisotropy problem.

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“…Fluctuations of interacting scalar fields in an inflating spacetime have been the focus of cosmologists [17]. Recently, there has been a revival of interest on IR dynamics of scalar potential models with various approaches that include extending the stochastic formalism [18], applying complementary series analysis [19], computing effective actions [20][21][22][23], using…”

Section: Introductionmentioning

confidence: 99%

Quantum effects of mass on scalar field correlations, power spectrum, and fluctuations during inflation

Karakaya

Onemli

2018

Phys. Rev. D

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We consider an infrared truncated massive minimally coupled scalar field with a quartic self-interaction in the locally de Sitter background of an inflating universe.We compute the two-point correlation function of the scalar and the mean squared fluctuations (variance) of the field variation analytically, at tree, one-and two-loop order. The one-loop correlator at a fixed comoving separation asymptotes to zero in the massive case but grows, at late times, like −λ ln 2 (a) in the massless limit, where a is the cosmic scale factor. For a fixed physical distance, on the other hand, it grows, at late times, like −λ ln 3 (a) in the massless limit. This growth is severely suppressed in the massive case. In fact, the one-loop correlator asymptotes effectively to zero for masses larger than half the expansion rate. We find out also that the tree-order variance of field variation decreases when quantum corrections are included. Hence, the actual effect that any local observer perceives in the field strength as fluctuations happen does not deviate from the average effect as much as the tree-order variance implies.

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Primordial cosmic fluctuations for variable gravity

Cited by 23 publications

References 85 publications

Graviton fluctuations erase the cosmological constant

Graviton fluctuations erase the cosmological constant

The slow expansion with nonminimal derivative coupling and its conformal dual

Quantum effects of mass on scalar field correlations, power spectrum, and fluctuations during inflation

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