Lattice quantum gravity and asymptotic safety

John W Laiho, S. Bassler, D. Coumbe, D. Du, J. T. Neelakanta

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

We study the nonperturbative formulation of quantum gravity defined via Euclidean dynamical triangulations (EDT) in an attempt to make contact with Weinberg's asymptotic safety scenario. We find that a fine-tuning is necessary in order to recover semiclassical behavior. Such a fine-tuning is generally associated with the breaking of a target symmetry by the lattice regulator; in this case we argue that the target symmetry is the general coordinate invariance of the theory. After introducing and fine-tuning a nontrivial local measure term, we find no barrier to taking a continuum limit, and we find evidence that four-dimensional, semiclassical geometries are recovered at long distance scales in the continuum limit. We also find that the spectral dimension at short distance scales is consistent with 3/2, a value that could resolve the tension between asymptotic safety and the holographic entropy scaling of black holes. We argue that the number of relevant couplings in the continuum theory is one, once symmetry breaking by the lattice regulator is accounted for. Such a theory is maximally predictive, with no adjustable parameters. The cosmological constant in Planck units is the only relevant parameter, which serves to set the lattice scale. The cosmological constant in Planck units is of order 1 in the ultraviolet and undergoes renormalization group running to small values in the infrared. If these findings hold up under further scrutiny, the lattice may provide a nonperturbative definition of a renormalizable quantum field theory of general relativity with no adjustable parameters and a cosmological constant that is naturally small in the infrared.

Original languageEnglish (US)
Article number064015
JournalPhysical Review D
Volume96
Issue number6
DOIs
StatePublished - Sep 12 2017

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safety
gravitation
regulators
tuning
continuums
triangulation
symmetry
relativity
invariance
broken symmetry
entropy
formulations
scaling
geometry

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Laiho, J. W., Bassler, S., Coumbe, D., Du, D., & Neelakanta, J. T. (2017). Lattice quantum gravity and asymptotic safety. Physical Review D, 96(6), [064015]. https://doi.org/10.1103/PhysRevD.96.064015

Lattice quantum gravity and asymptotic safety. / Laiho, John W; Bassler, S.; Coumbe, D.; Du, D.; Neelakanta, J. T.

In: Physical Review D, Vol. 96, No. 6, 064015, 12.09.2017.

Research output: Contribution to journalArticle

Laiho, JW, Bassler, S, Coumbe, D, Du, D & Neelakanta, JT 2017, 'Lattice quantum gravity and asymptotic safety', Physical Review D, vol. 96, no. 6, 064015. https://doi.org/10.1103/PhysRevD.96.064015
Laiho JW, Bassler S, Coumbe D, Du D, Neelakanta JT. Lattice quantum gravity and asymptotic safety. Physical Review D. 2017 Sep 12;96(6). 064015. https://doi.org/10.1103/PhysRevD.96.064015
Laiho, John W ; Bassler, S. ; Coumbe, D. ; Du, D. ; Neelakanta, J. T. / Lattice quantum gravity and asymptotic safety. In: Physical Review D. 2017 ; Vol. 96, No. 6.
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