scholarly journals Non-Trivial Ultraviolet Fixed Point in Quantum Gravity

1999 ◽  
Vol 102 (1) ◽  
pp. 181-195 ◽  
Author(s):  
Wataru Souma
Keyword(s):  
Fixed Point ◽  
Quantum Gravity

scholarly journals Dimension and Dimensional Reduction in Quantum Gravity

Universe ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 83 ◽  
Author(s):  
Steven Carlip
Keyword(s):  
Fixed Point ◽  
Quantum Gravity ◽  
Dimensional Reduction ◽  
Short Distance ◽  
Evidence Based ◽  
Two Dimensional ◽  
Anomalous Scaling ◽  
Lines Of Evidence ◽  
Quantum Spacetime

If gravity is asymptotically safe, operators will exhibit anomalous scaling at the ultraviolet fixed point in a way that makes the theory effectively two-dimensional. A number of independent lines of evidence, based on different approaches to quantization, indicate a similar short-distance dimensional reduction. I will review the evidence for this behavior, emphasizing the physical question of what one means by “dimension” in a quantum spacetime, and will discuss possible mechanisms that could explain the universality of this phenomenon.

scholarly journals Ultraviolet stable fixed point and scaling relations in (2 + ϵ)-dimensional quantum gravity

1993 ◽  
Vol 404 (3) ◽  
pp. 684-714 ◽  
Author(s):  
Hikaru Kawai ◽  
Yoshihisa Kitazawa ◽  
Masao Ninomiya
Keyword(s):  
Fixed Point ◽  
Quantum Gravity ◽  
Scaling Relations ◽  
Stable Fixed Point

scholarly journals Predictive power of grand unification from quantum gravity

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Astrid Eichhorn ◽  
Aaron Held ◽  
Christof Wetterich
Keyword(s):  
Fixed Point ◽  
Gauge Symmetry ◽  
Quantum Gravity ◽  
Predictive Power ◽  
Scalar Potential ◽  
Spontaneous Breaking ◽  
Grand Unification ◽  
Particle Content ◽  
Free Parameters

Abstract If a grand-unified extension of the asymptotically safe Reuter fixed-point for quantum gravity exists, it determines free parameters of the grand-unified scalar potential. All quartic couplings take their fixed-point values in the trans-Planckian regime. They are irrelevant parameters that are, in principle, computable for a given particle content of the grand unified model. In turn, the direction of spontaneous breaking of the grand-unified gauge symmetry becomes predictable. For the flow of the couplings below the Planck mass, gauge and Yukawa interactions compete for the determination of the minimum of the effective potential.

scholarly journals The derivative expansion in asymptotically safe quantum gravity: general setup and quartic order

2021 ◽  
Vol 4 (3) ◽  
Author(s):  
Benjamin Knorr
Keyword(s):  
Fixed Point ◽  
Quantum Gravity ◽  
General Framework ◽  
Derivative Expansion ◽  
Truncation Order ◽  
General Setup

We present a general framework to systematically study the derivative expansion of asymptotically safe quantum gravity. It is based on an exact decoupling and cancellation of different modes in the Landau limit, and implements a correct mode count as well as a regularisation based on geometrical considerations. It is applicable independent of the truncation order. To illustrate the power of the framework, we discuss the quartic order of the derivative expansion and its fixed point structure as well as physical implications.

scholarly journals Effective universality in quantum gravity

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Astrid Eichhorn ◽  
Peter Labus ◽  
Jan M. Pawlowski ◽  
Manuel Reichert
Keyword(s):  
Fixed Point ◽  
Quantum Gravity ◽  
Qualitative Agreement ◽  
Quantitative Agreement ◽  
Quantum Level ◽  
Asymptotic Safety ◽  
Gravity System ◽  
Scalar Gravity

We investigate the asymptotic safety scenario for a scalar-gravity system. This system contains two avatars of the dynamical Newton coupling, a gravitational self-coupling and a scalar-graviton coupling. We uncover an effective universality for the dynamical Newton coupling on the quantum level: its momentum-dependent avatars are in remarkable quantitative agreement in the scaling regime of the UV fixed point. For the background Newton coupling, this effective universality is not present, but qualitative agreement remains.

scholarly journals Fixed point structure of the conformal factor field in quantum gravity

2016 ◽  
Vol 94 (12) ◽  
Author(s):  
Juergen A. Dietz ◽  
Tim R. Morris ◽  
Zoë H. Slade
Keyword(s):  
Fixed Point ◽  
Quantum Gravity ◽  
Conformal Factor

scholarly journals Unimodular quantum gravity: steps beyond perturbation theory

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Gustavo P. de Brito ◽  
Antonio D. Pereira
Keyword(s):  
Fixed Point ◽  
Perturbation Theory ◽  
Renormalization Group ◽  
Quantum Gravity ◽  
Symmetry Breaking ◽  
Coarse Graining ◽  
Renormalization Group Flow ◽  
Anomalous Dimensions ◽  
Group Flow

Abstract The renormalization group flow of unimodular quantum gravity is computed by taking into account the graviton and Faddeev-Popov ghosts anomalous dimensions. In this setting, a ultraviolet attractive fixed point is found. Symmetry-breaking terms induced by the coarse-graining procedure are introduced and their impact on the flow is analyzed. A discussion on the equivalence of unimodular quantum gravity and standard full diffeomorphism invariant theories is provided beyond perturbation theory.

scholarly journals Quantum gravity, renormalizability and diffeomorphism invariance

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Tim Morris
Keyword(s):  
Hilbert Space ◽  
Fixed Point ◽  
Renormalization Group ◽  
Quantum Gravity ◽  
Master Equation ◽  
Conformal Factor ◽  
Quantum Master Equation ◽  
First Order ◽  
Diffeomorphism Invariance ◽  
Brst Cohomology

We show that the Wilsonian renormalization group (RG) provides a natural regularisation of the Quantum Master Equation such that to first order the BRST algebra closes on local functionals spanned by the eigenoperators with constant couplings. We then apply this to quantum gravity. Around the Gaussian fixed point, RG properties of the conformal factor of the metric allow the construction of a Hilbert space \Ll of renormalizable interactions, non-perturbative in \hbarℏ, and involving arbitrarily high powers of the gravitational fluctuations. We show that diffeomorphism invariance is violated for interactions that lie inside \Ll, in the sense that only a trivial quantum BRST cohomology exists for interactions at first order in the couplings. However by taking a limit to the boundary of \Ll, the couplings can be constrained to recover Newton’s constant, and standard realisations of diffeomorphism invariance, whilst retaining renormalizability. The limits are sufficiently flexible to allow this also at higher orders. This leaves open a number of questions that should find their answer at second order. We develop much of the framework that will allow these calculations to be performed.

A fixed point for quantum gravity

1982 ◽  
Vol 208 (3) ◽  
pp. 439-466 ◽  
Author(s):  
Lee Smolin
Keyword(s):  
Fixed Point ◽  
Quantum Gravity
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