Lorentzian Quantum Gravity and the Graviton Spectral Function

Fehre, Jannik; Pawlowski, Jan M.; Reichert, Manuel

doi:10.1103/physrevlett.130.081501

Cited by 38 publications

(23 citation statements)

References 53 publications

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“…The "form factors" g R ( ) and g C ( ) encode instead the physical momentum dependence of the quartic couplings [24,25,[31][32][33][34][35], generalizing the relation ∂ 2 ∼ −p 2 to curved spacetimes [31]. As the effective action (3) is the result of integrating over all quantum fluctuations, quantities computed using it already encode all quantum effects.…”

Section: Asymptotic Safety In a Nutshellmentioning

confidence: 99%

“…Here = −g µν D µ D ν is the d'Alembert operator built from a metric g, R stands for a generic curvature invariant, and f i ( ) are form factors, similarly to those we introduced in Eq. ( 3), that encode the physical momentum dependence of the gravitational couplings [24,25,[31][32][33][34][35]. Determin-ing them from first principles ought to be a task of every approach to quantum gravity.…”

Section: Quantum Gravity Constraints From the Principle Of Least Actionmentioning

confidence: 99%

“…FRG computations are typically performed in Euclidean. First steps towards Lorentzian calculations have been taken in[15][16][17][18][19][20][21][22][23][24], while Lorentzian computations based on the spectral FRG have been developed and applied in[25][26][27].…”

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confidence: 99%

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Black Holes in Asymptotically Safe Gravity

Platania¹

2023

Preprint

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In this chapter we review the state-of-the-art of black holes in asymptotically safe gravity. After a brief recap of the asymptotic safety program, we shall summarize the features of asymptotic-safety-inspired black-hole models that have been constructed in the past by the so-called renormalization group improvement. Specifically, we will discuss static configurations, both in spherically-and axiallysymmetric settings, the role played by the cosmological constant, and the impact of the collapse dynamics in determining black-hole configurations realized in Nature.In particular, we will review how quantum gravity could modify the Buchdahl limit and the corresponding conditions to form ultra-compact objects and Planckian black holes. We will then proceed by describing the most recent developments, particularly those aiming at making model building in asymptotic safety more rigorous and free from ambiguities. These include self-consistent and coordinate-independent versions of the renormalization group improvement, and next steps to fill the gap between model building and renormalization group computations in asymptotic safety. Finally, we will focus on a selection of results that have been obtained from first-principle calculations or arguments, within and beyond asymptotic safety. Concretely, we will review the state-of-the-art in determining black-hole entropy in asymptotic safety from a microstate counting, and progress in deriving the quantumcorrected Newtonian potential. We will discuss how in quantum gravity theories linked to a gravitational path integral singularity resolution could be achieved by a dynamical suppression of singular configurations. Finally, we will show thatindependent of the specific ultraviolet completion of gravity-asymptotic modifications to Schwarzschild black holes are strongly constrained by the principle of least action at large distance scales.

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Section: Asymptotic Safety In a Nutshellmentioning

confidence: 99%

Section: Quantum Gravity Constraints From the Principle Of Least Actionmentioning

confidence: 99%

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Black Holes in Asymptotically Safe Gravity

Platania¹

2023

Preprint

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“…In turn, for µ h → −1, these diagrams are enhanced. As discussed in [105], an on-shell analysis requires a non-trivial metric solution which compensates effects of the mass parameter but also changes the vertices. This implies that the physical consequences of a suppression or enhancement that originates in the value of the mass parameter, should be taken with a grain of salt: they are based on an off-shell background that can easily destroy the fixed-point properties.…”

Section: Variations Of the Regulator And Cutoff Scalesmentioning

confidence: 99%

The Asymptotically Safe Standard Model: From quantum gravity to dynamical chiral symmetry breaking

Pastor-Gutiérrez,

Pawlowski,

Reichert

2023

SciPost Phys.

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We present a comprehensive non-perturbative study of the phase structure of the asymptotically safe Standard Model. The physics scales included range from the asymptotically safe trans-Planckian regime in the ultraviolet, the intermediate high-energy regime with electroweak symmetry breaking to strongly correlated QCD in the infrared. All flows are computed with a self-consistent functional renormalisation group approach, using a vertex expansion in the fluctuation fields. In particular, this approach takes care of all physical threshold effects and the respective decoupling of ultraviolet degrees of freedom. Standard Model and gravity couplings and masses are fixed by their experimental low energy values. Importantly, we accommodate for the difference between the top pole mass and its Euclidean analogue. Both, the correct mass determination and the threshold effects have a significant impact on the qualitative properties, and in particular on the stability properties of the specific ultraviolet-infrared trajectory with experimental Standard Model physics in the infrared. We show that in the present rather advanced approximation the matter part of the asymptotically safe Standard Model has the same number of relevant parameters as the Standard Model, and is asymptotically free. This result is based on the novel UV fixed point found in the present work: the fixed point Higgs potential is flat but has two relevant directions. These results and their analysis are accompanied by a thorough discussion of the systematic error of the present truncation, also important for systematic improvements.

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“…This conjecture states that a theory with non-Gaussian fixed points, such that all the running coupling constants of the theory tends to them in the ultraviolet (UV) limit, is free of divergences and, therefore, is renormalizable and predictive. The search for fixed points in the case of gravitational interaction has been done [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Black strings in asymptotically safe gravity

Nilton,

Alencar,

Costa Filho

2024

Phys. Scr.

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In this paper, we study black strings in asymptotic safety gravity (ASG) scenario. The ASG approach is introduced by implementing gravitational and cosmological running coupling constants directly in the black string metric. We calculate the Hawking temperature, entropy, and heat capacity of the improved black string metric in two cases: considering the cosmological constant fixed in some fixed point and the general case where both Newton's constant and cosmological constant are improved. For the identification of the scale moment we used an general inverse law setting $k(r)\sim 1/r^{n}$. We show that improving only the Newton's constant the problem of singularity is solved for the identifications with $n>1$. However, if the cosmological constant is also running the singularity persists in the solution. Also, we show that the ASG effects predicts the presence of a remnant mass in the final evaporation process. Besides that, a logarithmic correction is observed in the entropy. However, a running cosmological constant introduces new correction terms to the entropy beyond that. We show that the improved black string solution remains stable, as in the usual case. Phase transitions are not observed in both cases studied here.

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Lorentzian Quantum Gravity and the Graviton Spectral Function

Cited by 38 publications

References 53 publications

Black Holes in Asymptotically Safe Gravity

Black Holes in Asymptotically Safe Gravity

The Asymptotically Safe Standard Model: From quantum gravity to dynamical chiral symmetry breaking

Black strings in asymptotically safe gravity

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