Quantum gravity and the functional renormalization group: the road towards asymptotic safety

2019 ◽  
Vol 60 (1) ◽  
pp. 104-105
Author(s):  
Eric Howard
Keyword(s):  
Renormalization Group ◽  
Quantum Gravity ◽  
Functional Renormalization Group ◽  
Asymptotic Safety ◽  
The Road

scholarly journals ASYMPTOTIC SAFETY IN HIGHER-DERIVATIVE GRAVITY

2009 ◽  
Vol 24 (28) ◽  
pp. 2233-2241 ◽  
Author(s):  
DARIO BENEDETTI ◽  
PEDRO F. MACHADO ◽  
FRANK SAUERESSIG
Keyword(s):  
Fixed Point ◽  
Renormalization Group ◽  
Renormalization Group Flow ◽  
Functional Renormalization Group ◽  
Asymptotic Safety ◽  
Higher Derivative ◽  
Gravity Theories ◽  
Group Flow ◽  
Nonperturbative Renormalization

We study the nonperturbative renormalization group flow of higher-derivative gravity employing functional renormalization group techniques. The nonperturbative contributions to the β-functions shift the known perturbative ultraviolet fixed point into a nontrivial fixed point with three UV-attractive and one UV-repulsive eigendirections, consistent with the asymptotic safety conjecture of gravity. The implication of this transition on the unitarity problem, typically haunting higher-derivative gravity theories, is discussed.

scholarly journals Consistency of matter models with asymptotically safe quantum gravity

2015 ◽  
Vol 93 (9) ◽  
pp. 988-994 ◽  
Author(s):  
Pietro Donà ◽  
Astrid Eichhorn ◽  
Roberto Percacci
Keyword(s):  
Renormalization Group ◽  
Standard Model ◽  
Quantum Gravity ◽  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Matter Content ◽  
Asymptotic Safety ◽  
The Standard Model ◽  
Renormalization Group Flows ◽  
Matter Fields

We discuss the compatibility of quantum gravity with dynamical matter degrees of freedom. Specifically, we present bounds we obtained in Donà et al. (Phys. Rev. D, 89, 084035 (2014) doi:10.1103/PhysRevD.89.084035 ) on the allowed number and type of matter fields within asymptotically safe quantum gravity. As a novel result, we show bounds on the allowed number of spin-3/2 (Rarita–Schwinger) fields (e.g., the gravitino). These bounds, obtained within truncated renormalization group flows, indicate the compatibility of asymptotic safety with the matter fields of the standard model. Further, they suggest that extensions of the matter content of the standard model are severely restricted in asymptotic safety. This means that searches for new particles at colliders could provide experimental tests for this particular approach to quantum gravity.

scholarly journals MULTIFRACTIONAL SPACETIMES, ASYMPTOTIC SAFETY AND HOŘAVA–LIFSHITZ GRAVITY

2013 ◽  
Vol 28 (19) ◽  
pp. 1350092 ◽  
Author(s):  
GIANLUCA CALCAGNI
Keyword(s):  
Renormalization Group ◽  
Quantum Gravity ◽  
Fractal Structure ◽  
Scale Dependence ◽  
Field Theories ◽  
Position Space ◽  
Asymptotic Safety ◽  
Alternative Perspective ◽  
Measurement Tools

We compare the recently formulated multifractional spacetimes with field theories of quantum gravity based on the renormalization group (RG), such as asymptotic safety and Hořava–Lifshitz gravity. The change of spacetime dimensionality with the probed scale is realized in both cases by an adaptation of the measurement tools ("rods") to the scale, but in different ways. In the multifractional case, by an adaptation of the position-space measure, which can be encoded into an explicit scale dependence of effective coordinates. In the case of RG-based theories, by an adaptation of the momenta. The two pictures are mapped into each other, thus presenting the fractal structure of spacetime in RG-based theories under an alternative perspective.

scholarly journals Towards a Geometrization of Renormalization Group Histories in Asymptotic Safety

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 125
Author(s):  
Renata Ferrero ◽  
Martin Reuter
Keyword(s):  
Renormalization Group ◽  
Killing Vector ◽  
Einstein Gravity ◽  
Riemann Tensor ◽  
Dimensional Manifold ◽  
Riemannian Structure ◽  
Functional Renormalization Group ◽  
Asymptotic Safety ◽  
Higher Dimensional ◽  
Natural Foliation

Considering the scale-dependent effective spacetimes implied by the functional renormalization group in d-dimensional quantum Einstein gravity, we discuss the representation of entire evolution histories by means of a single, (d+1)-dimensional manifold furnished with a fixed (pseudo-) Riemannian structure. This “scale-spacetime” carries a natural foliation whose leaves are the ordinary spacetimes seen at a given resolution. We propose a universal form of the higher dimensional metric and discuss its properties. We show that, under precise conditions, this metric is always Ricci flat and admits a homothetic Killing vector field; if the evolving spacetimes are maximally symmetric, their (d+1)-dimensional representative has a vanishing Riemann tensor even. The non-degeneracy of the higher dimensional metric that “geometrizes” a given RG trajectory is linked to a monotonicity requirement for the running of the cosmological constant, which we test in the case of asymptotic safety.

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