Quantum Gravity in Everyday Life: General Relativity as an Effective Field Theory

“…This theory is non-renormalizable and should be understood as an effective theory [177,196]. To see this, let us expand the metric in terms of small perturbations around flat space, g µν ≡ η µν + 1 M pl h µν .…”

Section: Gravitymentioning

confidence: 99%

Inflation and String Theory

2015

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“…of the theory [6][7][8][9][10][11][12][13][14]. The unitarity methods deal directly with on-shell and low energy amplitudes, and products of on-shell tree amplitudes can therefore yield the low energy one-loop results in a conceptually simple manner.…”

Section: Jhep02(2014)111mentioning

confidence: 99%

“…9) where S µν,ρσ arises from the axial-gauge polarization sum 10) with S µν the axial-gauge spin 1 polarization sum…”

Section: Jhep02(2014)111mentioning

confidence: 99%

On-shell techniques and universal results in quantum gravity

Bjerrum-Bohr¹,

Donoghue

Vanhove

2014

J. High Energ. Phys.

197

222

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Abstract:We compute the leading post-Newtonian and quantum corrections to the Coulomb and Newtonian potentials using the full modern arsenal of on-shell techniques; we employ spinor-helicity variables everywhere, use the Kawai-Lewellen-Tye (KLT) relations to derive gravity amplitudes from gauge theory and use unitarity methods to extract the terms needed at one-loop order. We stress that our results are universal and thus will hold in any quantum theory of gravity with the same low-energy degrees of freedom as we are considering. Previous results for the corrections to the same potentials, derived historically using Feynman graphs, are verified explicitly, but our approach presents a huge simplification, since starting points for the computations are compact and tedious index contractions and various complicated integral reductions are eliminated from the onset, streamlining the derivations. We also analyze the spin dependence of the results using the KLT factorization, and show how the spinless corrections in the framework are easily seen to be independent of the interacting matter considered.

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“…Subsection 2.3 discusses the particular case of flat space and how to deal with the translational invariance that arises. Then Section 3 repeats the main calculation for the modified path integral resulting from (6), showing that the semiclassical results are unchanged and therefore that, under certain assumptions, the semiclassical regime of spin foams matches that of Regge calculus. Section 4 is a discussion of the results and suggestions for further work.…”

Section: Introductionmentioning

confidence: 98%

Semiclassical regime of Regge calculus and spin foams

Bianchi

Satz

2009

Nuclear Physics B

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Recent attempts to recover the graviton propagator from spin foam models involve the use of a boundary quantum state peaked on a classical geometry. The question arises whether beyond the case of a single simplex this suffices for peaking the interior geometry in a semiclassical configuration. In this paper we explore this issue in the context of quantum Regge calculus with a general triangulation. Via a stationary phase approximation, we show that the boundary state succeeds in peaking the interior in the appropriate configuration, and that boundary correlations can be computed order by order in an asymptotic expansion. Further, we show that if we replace at each simplex the exponential of the Regge action by its cosine -as expected from the semiclassical limit of spin foam models -then the contribution from the sign-reversed terms is suppressed in the semiclassical regime and the results match those of conventional Regge calculus.

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Quantum Gravity in Everyday Life: General Relativity as an Effective Field Theory

Abstract: This article is meant as a summary and introduction to the ideas of effective field theory as applied to gravitational systems, ideas which provide the theoretical foundations for the modern use of general relativity as a theory from which precise predictions are possible.

Cited by 604 publications

References 137 publications

Inflation and String Theory

Inflation and String Theory

On-shell techniques and universal results in quantum gravity

Semiclassical regime of Regge calculus and spin foams

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