scholarly journals Gauge assisted quadratic gravity: A framework for UV complete quantum gravity

2018 ◽  
Vol 97 (12) ◽  
Author(s):  
John F. Donoghue ◽  
Gabriel Menezes
Keyword(s):  
Quantum Gravity ◽  
Quadratic Gravity ◽  
Complete Quantum

scholarly journals Quadratic gravity: From weak to strong

2016 ◽  
Vol 25 (12) ◽  
pp. 1643004 ◽  
Author(s):  
Bob Holdom ◽  
Jing Ren
Keyword(s):  
General Relativity ◽  
Nonperturbative Effects ◽  
Quantum Gravity ◽  
Quantum Chromodynamics ◽  
Free Theory ◽  
Strongly Interacting ◽  
Quadratic Gravity ◽  
Free Interaction

More than three decades ago quadratic gravity was found to present a perturbative, renormalizable and asymptotically free theory of quantum gravity. Unfortunately, the theory appeared to have problems with a spin-2 ghost. In this essay, we revisit quadratic gravity in a different light by considering the case that the asymptotically free interaction flows to a strongly interacting regime. This occurs when the coefficient of the Einstein–Hilbert term is smaller than the scale [Formula: see text] where the quadratic couplings grow strong. Here quantum chromodynamics (QCD) provides some useful insights. By pushing the analogy with QCD, we conjecture that the nonperturbative effects can remove the naive spin-2 ghost and lead to the emergence of general relativity (GR) in the IR.

scholarly journals Holographic Screens in Ultraviolet Self-Complete Quantum Gravity

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Piero Nicolini ◽  
Euro Spallucci
Keyword(s):  
Quantum Gravity ◽  
Terminal Phase ◽  
Logarithmic Term ◽  
Fundamental Building Block ◽  
Extremal Configuration ◽  
Holographic Screen ◽  
Discrete Mass ◽  
Complete Quantum ◽  
Area Law ◽  
Screen Surface

This paper studies the geometry and the thermodynamics of aholographic screenin the framework of the ultraviolet self-complete quantum gravity. To achieve this goal we construct a new static, neutral, nonrotating black hole metric, whose outer (event) horizon coincides with the surface of the screen. The spacetime admits an extremal configuration corresponding to the minimal holographic screen and having both mass and radius equalling the Planck units. We identify this object as the spacetime fundamental building block, whose interior is physically unaccessible and cannot be probed even during the Hawking evaporation terminal phase. In agreement with the holographic principle, relevant processes take place on the screen surface. The area quantization leads to a discrete mass spectrum. An analysis of the entropy shows that the minimal holographic screen can store only one byte of information, while in the thermodynamic limit the area law is corrected by a logarithmic term.

scholarly journals Hawking radiation from the holographic screen

2017 ◽  
Vol 32 (31) ◽  
pp. 1750162
Author(s):  
Ying-Jie Zhao
Keyword(s):  
Quantum Gravity ◽  
Hawking Radiation ◽  
Tunneling Probability ◽  
Hawking Temperature ◽  
Holographic Screen ◽  
Complete Quantum

In this paper, we generalize the Parikh–Wilczek scheme to a holographic screen in the framework of the ultraviolet self-complete quantum gravity. We calculate that the tunneling probability depends on the energy of the particle and the mass of the holographic screen. The radiating temperature has not been the standard Hawking temperature.

scholarly journals Exorcising ghosts in quantum gravity

2020 ◽  
Vol 135 (10) ◽  
Author(s):  
Iberê Kuntz
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Gravity ◽  
Boundary Conditions ◽  
Finite Number ◽  
Integration Contour ◽  
Quantum Field ◽  
Curvature Invariants ◽  
Higher Derivative ◽  
Quadratic Gravity

AbstractWe remark that Ostrogradsky ghosts in higher-derivative gravity, with a finite number of derivatives, are fictitious as they result from an unjustified truncation performed in a complete theory containing infinitely many curvature invariants. The apparent ghosts can then be projected out of the quadratic gravity spectrum by redefining the boundary conditions of the theory in terms of an integration contour that does not enclose the ghost poles. This procedure does not alter the renormalizability of the theory. One can thus use quadratic gravity as a quantum field theory of gravity that is both renormalizable and unitary.

scholarly journals Black holes production in self-complete quantum gravity

2012 ◽  
Vol 709 (3) ◽  
pp. 266-269 ◽  
Author(s):  
Euro Spallucci ◽  
Anais Smailagic
Keyword(s):  
Black Holes ◽  
Quantum Gravity ◽  
Complete Quantum

scholarly journals A Second Law for higher curvature gravity

2015 ◽  
Vol 24 (12) ◽  
pp. 1544014 ◽  
Author(s):  
Aron C. Wall
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Entanglement Entropy ◽  
Black Hole Thermodynamics ◽  
Gravity Theory ◽  
Second Law ◽  
Holographic Entanglement Entropy ◽  
Higher Curvature Gravity ◽  
Complete Quantum

The Second Law of black hole thermodynamics is shown to hold for arbitrarily complicated theories of higher curvature gravity, so long as we allow only linearized perturbations to stationary black holes. Some ambiguities in Wald’s Noether charge method are resolved. The increasing quantity turns out to be the same as the holographic entanglement entropy calculated by Dong. It is suggested that only the linearization of the higher curvature Second Law is important, when consistently truncating a UV-complete quantum gravity theory.

scholarly journals On the Structure of the Vacuum in Quantum Gravity: A View from the Asymptotic Safety Scenario

Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 182 ◽  
Author(s):  
Alfio Bonanno
Keyword(s):  
Quantum Gravity ◽  
Degrees Of Freedom ◽  
Vacuum State ◽  
Critical Surface ◽  
Asymptotic Safety ◽  
Quantum Chromo Dynamics ◽  
Full Theory ◽  
Higher Derivative ◽  
Quadratic Gravity ◽  
Non Gaussian

Although the Asymptotic Safety scenario is one of the most promising approaches to quantum gravity, little attention has been devoted to the issue of the vacuum state. Higher derivative operators often appear on the ultraviolet critical surface around the non-Gaussian fixed point generating additional degrees of freedom which can render the standard vacuum unstable. When this happens, translation and rotational symmetries can be spontaneously broken and a new set of symmetries can show up at the level of the effective action. In this work, it will be argued that a “kinetic condensate” characterizes the vacuum state of asymptotically safe quadratic gravity theories. If this scenario is realized in the full theory, the vacuum state of gravity is the gravitational analogous to the Savvidy vacuum in Quantum Chromo-Dynamics (QCD).

scholarly journals Black holes in an ultraviolet complete quantum gravity

2011 ◽  
Vol 695 (1-4) ◽  
pp. 397-400 ◽  
Author(s):  
Leonardo Modesto ◽  
John W. Moffat ◽  
Piero Nicolini
Keyword(s):  
Black Holes ◽  
Quantum Gravity ◽  
Complete Quantum
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