Physical cosmological constant in asymptotically background-free quantum gravity

Hamada, Kenji; Matsuda, Mikoto

doi:10.1103/physrevd.96.026010

Cited by 9 publications

(16 citation statements)

References 58 publications

(112 reference statements)

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“…Here, we will calculate the effective action of massless QED in curved spacetime to confirm the form (2.5) at the 3-loop level. As a method to perform the renormalization calculations, dimensional regularization is employed [1,2,3,4,5,6,7,8,9,10,18,19,20,21,22]. This is the only known regularization method that can do high-loop calculations while preserving diffeomorphism invariance as well as gauge invariance.…”

Section: Qed Effective Action and Diffeomorphism Invariancementioning

confidence: 99%

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Diffeomorphism Invariance Demands Conformal Anomalies

Hamada

2020

Preprint

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We study a series of the Wess-Zumino actions obtained by repeatedly integrating conformal anomalies with respect to the conformalfactor field that appear at higher loops. We show that they arise as physical quantities required to make nonlocal loop correction terms diffeomorphism invariant. Specifically, in a conformally flat spacetime ds 2 = e 2φ (−dη 2 + dx 2 ), we find that effective actions are described in terms of momentum squared expressed as a physical Q 2 = q 2 /e 2φ for q 2 measured by the flat metric, which recalls the relationship between physical momentum and comoving momentum in cosmology. It is confirmed by calculating the effective action of QED in such a curved spacetime at the 3-loop level using dimensional regularization. The same applies to the case of QCD, in which we show that the effective action can be summarized in the form of the reciprocal of a running coupling constant squared described by the physical momentum. We also see that the same holds for renormalizable quantum conformal gravity and that conformal anomalies are indispensable for formulating the theory.

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Section: Qed Effective Action and Diffeomorphism Invariancementioning

confidence: 99%

“…Here, t is a coupling constant that controls dynamics of traceless tensor fields in renormalizable quantum conformal gravity [17,18,19,20,21,22].…”

Section: Effective Actions Of Qcd and Quantum Gravitymentioning

confidence: 99%

Diffeomorphism Invariance Demands Conformal Anomalies

Hamada

2020

Preprint

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“…Here, to overcome such a problem, we argue that spacetime will transition to a new phase before reaching the wall, and a quantum world without singularities will come out. Renormalizable asymptotically background-free quantum gravity [1,2,3,4,5,6] formulated based on a certain conformal field theory [7,8,9,10,11,12,13,6] suggests the existence of a dynamical energy scale that clearly separates quantum spacetime from classical spacetime.…”

Section: Introductionmentioning

confidence: 99%

“…Although negative-metric modes are necessary components for the BRST conformal algebra to close at the quantum level, we can show that 1 Normally, renormalization is done by replacing h µ ν with th µ ν . On the other hand, φ has no own coupling constant, thus the non-renormalization theorem holds for it [2,3,4,5]. they all are not gauge invariant, and thus do not appear as physical states 2 .…”

Section: Introductionmentioning

confidence: 99%

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Localized massive excitation of quantum gravity as a dark particle

Hamada

2020

Preprint

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We construct a static and spherical excited state without singularities in renormalizable quantum gravity with background-free nature asymptotically. Its diameter is given by a correlation length of the quantum gravity, and it has a Schwarzschild tail. The inside where nonperturbative dynamics are activated and the tail outside are smoothly connected by introducing a running coupling given by a function of the radial coordinate. If the mass is several times the Planck mass, we can obtain it as a solution of linearized equations of motion for the gravitational potentials incorporating the running effect. It may be a candidate for dark matter, and will give a new perspective on black hole physics.

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Revealing a trans-Planckian world solves the cosmological constant problem

Hamada¹

2022

Progress of Theoretical and Experimental Physics

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The Planck scale has been believed to be an unpassable wall. Putting a cutoff there and thinking of it as a quantized spacetime entity shows that. However, this is exactly the cause of many problems in quantum gravity. The cosmological constant problem also comes down to the problem of how to describe a trans-Planckian world by a continuum theory, which shall be renormalizable and background free. Here, we show that quantizing gravity in a diffeomorphism invariant method in which background freedom arises asymptotically as an exact conformal symmetry, zero-point energy vanishes identically. Thus, there is no problem with the cosmological constant, which is a physical constant, namely a renormalization group invariant. We also argue that new quanta based on the background freedom emerge and spacetime is discretized dynamically. Primordial fluctuations will be originated from such quanta.

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Physical cosmological constant in asymptotically background-free quantum gravity

Cited by 9 publications

References 58 publications

Diffeomorphism Invariance Demands Conformal Anomalies

Diffeomorphism Invariance Demands Conformal Anomalies

Localized massive excitation of quantum gravity as a dark particle

Revealing a trans-Planckian world solves the cosmological constant problem

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