REVIEW 3 major objections 4 minor 10 cited by
Matter Spectral Functions from Quantum Gravity
T0 review · 3 major / 4 minor · reviewed 2026-08-06 · deepseek-v4-flash
Pith's one-line read In asymptotically safe quantum gravity, photon and scalar propagators keep a Källén–Lehmann form, but their spectral functions turn negative and non-normalisable in the ultraviolet.
desk verdict A serious, technically demanding first computation of matter spectral functions in Lorentzian asymptotically safe gravity, but the KL representation and UV sign flip are assumed rather than demonstrated. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The machinery is the spectral renormalisation group: the functional renormalisation group flow (11) with a Callan-Symanzik-type regulator $R_{k,\Phi}=Z_\Phi k^2$ for bosons and $R_{k,\psi}=Z_\psi k\,\mathbb{1}$ for fermions, which shifts masses by the cutoff $k$ without introducing cuts or poles in the complex momentum plane. The load-bearing ansatz is Eq. (16), which fixes each matter spectral function as an on-shell delta peak plus two continua with thresholds at $m_\Phi+m_h$ and $2m_\psi$. Internal propagators are replaced by their spectral representations, and the flow of the two-point function is projected on the delta-peak part only, turning the integro-differential spectral flow into ordinary differential equations for the mass parameters, anomalous dimensions, and continuum functions. UV divergences are handled by dimensional regularisation and momentum-independent counterterms renormalised at vanishing momentum. The anomalous dimensions extracted from the delta-peak projection set the ultraviolet scaling of the continua.
What would settle it
Re-solve the flow equations (14) with the multi-particle continua $f_{\Phi,\mathrm{grav}}$ and $f_{\Phi,\mathrm{ferm}}$ kept on the right-hand side; if the spectral functions at $k=0$ no longer turn negative for $\lambda\gtrsim M_{\mathrm{Pl}}$, the ultraviolet sign flip is an artifact of the delta-peak-only truncation. A complementary check is to compute the scattering spectral function of $G_{A,\mathrm{scat}}$ in Eq. (47) with quantum-corrected vertices and test whether it is positive semi-definite.
Extended reading notes
Core claim
The central claim is that in a Lorentzian gravity-matter system with an asymptotically safe fixed point, the full photon and scalar propagators each satisfy a Källén–Lehmann representation with spectral function $\rho_\Phi(\lambda)=Z_\Phi^{-1}[2\pi\delta(\lambda^2-m_\Phi^2)+\theta(\lambda^2-(m_\Phi+m_h)^2)f_{\Phi,\mathrm{grav}}(\lambda)+\theta(\lambda^2-4m_\psi^2)f_{\Phi,\mathrm{ferm}}(\lambda)]$. On the UV-safe trajectory the graviton and fermion loops generate continua whose ultraviolet scaling is $\propto\lambda^{\eta_\Phi^*-2}$; with fixed-point anomalous dimensions $\eta_A^*\approx 0.52$ and $\eta_\phi^*\approx 0.045$, the spectral functions decay more slowly than a free propagator and are therefore non-normalisable. Around the Planck scale both $\rho_A$ and $\rho_\phi$ change sign, driven by the graviton diagram with the matter regulator insertion, which is negative and dominates in the ultraviolet. The paper stresses that the persistence of a Källén–Lehmann form is itself non-trivial, since complex conjugate poles or other non-analyticities could have destroyed it; no such behaviour is seen. The associated form factors inherit the branch cut structure and diverge and turn negative above the Planck scale, which the authors read as a signal that classical vertices cannot be used for amplitudes in that regime.
Load-bearing premise
The computation assumes from the outset that every propagator has a Källén–Lehmann form with one delta peak and two smooth continua, and it neglects the feedback of those continua into the flow equations, so the spectral representation is an input rather than something the calculation itself could disprove.
Editorial extensions
If this is right
- Photons and uncharged scalars lose their status as physical observables above the Planck scale: their spectral functions become gauge-dependent, non-normalisable, and partly negative.
- Below the Planck scale and above the fermion threshold, the universal fermion-loop contribution dominates and is positive, so matter spectral functions remain effectively physical in the infrared.
- The form factors $f_{FF}(p^2)$ and $f_{\phi\phi}(p^2)$ diverge and become negative around the Planck scale, so scattering amplitudes built from these propagators and classical vertices are not trustworthy in the ultraviolet.
- An asymptotically safe fixed point with $g_Y^*=0.455$ and $y_t^*=0.462$ provides a UV completion for the U(1) and Yukawa couplings if the gravitational coefficients $f_g$ and $f_y$ are positive as assumed.
- The sign flip in the scalar spectral function is robust (positivity would require $\eta_h^*\lesssim -54$), while the photon case is marginal (positivity requires $\eta_h^*\lesssim 0.3$), so the photon prediction is the more easily tested one.
Reading between the lines
- A consequence the authors leave implicit is that the negative, non-normalisable scalar spectral function, if confirmed beyond the quenched approximation, would forbid uncharged elementary scalars from appearing as asymptotic states in the deep ultraviolet of any asymptotically safe theory.
- The gauge-independent scattering propagator $G_{A,\mathrm{scat}}$ of Eq. (47) offers a sharper falsifier than the propagator itself: once quantum-corrected vertices are computed, its spectral function must be positive semi-definite if the theory is unitary.
- The same spectral-RG computation could be repeated with the multi-particle continuum fed back into the flow; in the deep infrared this changes the gauge-field spectral function by about 8.4%, and the interesting question is whether the Planck-scale sign flip shifts or disappears under that feedback.
- Since the Planck-scale peak is tied to the complex-conjugate critical exponents of the Newton coupling, the sign flip may also appear in other observables that couple to the graviton spectral function near the Planck scale, such as the $e^+e^-\to\mu^+\mu^-$ cross section computed with the same methods.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper develops a spectral renormalisation-group framework in Lorentzian signature with a Callan-Symanzik regulator and applies it to a gravity-matter system containing a U(1) gauge field, an uncharged scalar, and a fermion with Yukawa coupling. The authors compute the photon and scalar two-point functions, extract their spectral functions under the ansatz of Eq. (16), and obtain UV-IR trajectories with an interacting fixed point. They report that both matter spectral functions are non-normalisable, turn negative around the Planck scale, and depend on the gravity gauge-fixing parameters, with the fermion-loop contribution universal and positive below the Planck scale. They also translate the spectral functions into effective-action form factors and discuss implications for unitarity and scattering amplitudes.
Significance. If the central result held, it would be an important step in understanding whether matter fields coupled to asymptotically safe quantum gravity admit Källén-Lehmann representations and whether photons and uncharged scalars remain physical observables above the Planck scale. The paper is careful in several respects: the deep-IR comparison against one-loop effective field theory (Sec. VI C) is a concrete, quantitative check; the authors explicitly list their approximations in Sec. IV; they state the gauge-dependence of the matter spectral functions; and they provide the flow equations and a supplementary Mathematica notebook, which aids reproducibility. The qualitative message, however, is currently stronger than the evidence: the KL representation is assumed rather than derived, and the UV sign flip is not independently validated beyond the specific delta-peak projection. If the authors can reframe the claim and quantify the truncation error, the paper would be a valuable contribution; as it stands, the headline result is partly circular.
major comments (3)
- [Sec. III A, Sec. III C, Eq. (16), Sec. VI B] The central claim that the photon and scalar propagators possess a Källén-Lehmann spectral representation is not a derived output. Equation (7) is assumed for the full propagator factors, and Eq. (16) further restricts the spectral function to an on-shell delta peak plus two multi-particle continua with fixed thresholds. Consequently, the statement in Sec. VI B that the authors 'do not observe' complex conjugate poles or other non-analyticities is true only by construction: such structures are excluded by the ansatz. To make the KL claim non-circular, the authors need either to derive the absence of competing singularities from the flow equations or to test an enlarged ansatz that allows complex poles/branch cuts and show that they are not generated.
- [Sec. IV, Sec. VI C, Eq. (14)] The approximation of keeping only the delta-peak contribution on the right-hand side of the spectral flow (Sec. IV) turns an integro-differential equation into an ODE, but its error is only quantified in the deep IR. The comparison between Eqs. (39) and (38) gives a relative shift of 8.4% for the gauge field, yet this probes spectral values below the fermion threshold, whereas the sign flip and the asymptotic scaling \rho \propto \lambda^{\eta^*_\Phi - 2} occur around and above the Planck scale (Fig. 4). No analogous check constrains the UV region. The authors should either include the continuous parts of the spectral functions in the flow at least at leading order, or provide another estimate of the UV truncation error; without this, the sign flip and non-normalisability are not established beyond the specific projection used.
- [Sec. VI C, Eqs. (40)-(41)] The stability analysis with \eta_h^* treated as a free parameter is informative but incomplete as stated. The bounds \eta_h^*|_{\rm gauge} \lesssim 0.3 and \eta_h^*|_{\rm scalar} \lesssim -54 show that positivity of the scalar spectral function is far from the computed value \eta_h^* \approx 0.96, but the sentence that 'extended approximations are not expected to induce quantitatively significant changes in anomalous dimensions' is an assertion, not an estimate. The authors should provide a concrete error estimate for \eta_h^* (for example from the difference between the Lorentzian and Euclidean extractions, or from the dependence on the regulator) before claiming that the sign change is 'hard-wired' for the scalar.
minor comments (4)
- [Sec. IV, Eq. (23), Sec. VI C, Eq. (37)] The symbol \beta is used both for the beta functions of the Yukawa and gauge couplings and for the gravitational gauge-fixing parameter in Eq. (37); this notational clash should be resolved, for instance by renaming the gauge-fixing parameter.
- [Sec. VI A, Fig. 4] The text describes the fermion mass as 'm_\psi = 10^{-2} M_{\rm Pl}' but the figure caption says '10^{-2}M_{\rm Pl}'; the units and the illustrative nature of the value should be stated consistently in both places.
- [Abstract and Sec. VII] The phrase 'we show that both possess a Källén-Lehmann spectral representation' should be softened to reflect that the representation is imposed by the ansatz in Eq. (16) and then found to be consistent with the projected flow; otherwise the abstract overstates the logical status of the result.
- [Sec. IV, Eq. (21)] The trajectory for the fermion mass parameter \mu_\psi is an input rather than a result, and the claim that c_1 has 'strongly sub-leading influence' is only checked for the particular ranges shown; this should be stated explicitly in the main text near Eq. (21).
Circularity Check
The claimed KL representation is an input of the spectral ansatz (16), so the 'non-trivial' existence result is circular; the negative UV spectral functions remain genuine outputs.
-
self definitional
[Sec. III A, Sec. III C Eq. (16), Sec. VI B]
"Together with the on-shell delta peak, this leads to the following ansatz for the spectral function of the gauge and scalar field, rho_Phi = 1/Z_Phi [2 pi delta(lambda^2 - m_Phi^2) + theta(lambda^2 - (m_Phi + m_h)^2) f_Phi,grav(lambda) + theta(lambda^2 - 4 m_psi^2) f_Phi,ferm(lambda)], which holds for both Phi = {A, phi}. ... First of all, it is non-trivial that the gauge and scalar propagators possess a KL spectral representation after the inclusion of quantum gravity fluctuations."
The KL representation is not derived; it is imposed. Equation (7) is introduced with 'we use the KL spectral representation', and Eq. (16) restricts every matter propagator to an on-shell delta peak plus two real multi-particle thresholds. Complex-conjugate poles, momentum-dependent residues, or other non-analytic structures are thereby excluded from the function space by construction. The later statement in Sec. VI B that such poles are 'not observed' is therefore guaranteed by the ansatz rather than being a test of the KL property.
full rationale
The non-circular core is the computation: with the spectral ansatz (16) and the quenched delta-peak projection, the paper solves explicit flow equations and obtains the continuum functions, the fermion-threshold peak, the sign flip, and the non-normalisable asymptotic tails. None of these are fitted to the final spectral functions, and the deep-IR comparison against one-loop EFT (relative shift about 8.4%) is a genuine independent check, albeit one that probes only low energies. The circularity is confined to the existence claim: the KL representation is assumed in Eq. (7) and its specific form is fixed by Eq. (16), so the statement in Sec. VI B that the KL property is 'non-trivial' and that complex poles are 'not observed' is true only in the sense that the ansatz cannot represent such poles. The paper is transparent about this, and it also transparently imports the gravity-sector flows from [35]; that self-citation is load-bearing for the numerical value eta*_h ~ 0.96 used in the sign-flip analysis, but it is a published separate computation and is not itself a reduction of the matter result to the present paper's own input. The negative, non-normalisable matter spectral functions are consequences of the flow, not of any fit, so they are not circular. Overall, the central existence claim reduces by construction, giving a partial circularity score of 6, while the genuine quantitative results keep the paper from being fully circular.
Assumptions & free parameters
free parameters (5)
- fy (gravity coefficient in Yukawa beta function) =
0.00573 (asymptotically safe trajectory)
- fg (gravity coefficient in U(1) beta function) =
0.00847 (asymptotically safe trajectory)
- c1 (UV fixed-point value of fermion mass parameter) =
unspecified, varied
- c2 (physical fermion mass in Planck units) =
10^-2 for the illustrative figures
- gravity gauge-fixing parameters alpha, beta =
alpha = beta = 1
assumptions (6)
- domain assumption Asymptotic safety of the coupled gravity-matter system provides a UV completion.
- ad hoc to paper The full propagator admits a Källén-Lehmann representation (Eq. (7)).
- domain assumption The Callan-Symanzik regulator R_k = Z k^2 preserves spectral representations and is admissible in Lorentzian signature.
- ad hoc to paper Quenched approximation: matter loops do not feed back into Newton coupling, mass parameters, or anomalous dimensions; multi-particle continua do not feed back into the flow.
- ad hoc to paper One-loop beta functions for gauge and Yukawa couplings with constant gravity coefficients fy and fg (Eq. (23)).
- ad hoc to paper Renormalisation conditions at vanishing momentum (Eq. (13)) and boundary conditions Lambda = 0, omega_phi = 0, Z_i -> 1 at k -> 0.
Cite this review
Pith. "Pith review of Matter Spectral Functions from Quantum Gravity." pith.science (2026). https://pith.science/paper/H6YHECGO
@misc{pith2026250717862,
author = {Pith},
title = {Pith review of: Matter Spectral Functions from Quantum Gravity},
year = {2026},
howpublished = {\url{https://pith.science/paper/H6YHECGO}},
note = {Machine review of arXiv:2507.17862}
}
read the original abstract
We investigate Lorentzian quantum gravity coupled to a template matter sector with gauge fields, scalars and fermions. In the absence of quantised gravity, the matter sector by itself is renormalisable, but UV-incomplete. Provided quantum gravity offers an asymptotically safe UV-completion, we determine the photon and scalar two-point functions in the presence of gravitational fluctuations, and show that both possess a K\"all\'en-Lehmann spectral representation. Our results are achieved using functional renormalisation adapted for theories in Lorentzian signature. We explain why and how interactions with gravity modify both the infrared as well as the ultraviolet behaviour of matter spectral functions. We further determine the corresponding form factors on the level of the quantum effective action. Limitations and extensions of our study are discussed alongside implications for particle physics and unitarity of quantum gravity with matter.
Forward citations
Cited by 10 Pith papers
-
The fermion sector of the SMEFT from asymptotically safe gravity
In a toy model of one quark generation, asymptotically safe gravity predicts four-fermion SMEFT coefficients are either Planck-scale suppressed or zero, with exceptions only at very large gravitational coupling.
-
Spectral Functions of Lorentzian Quantum Gravity
Spectral functions for graviton and scalar graviton modes are derived in Lorentzian asymptotically safe quantum gravity via adapted FRG flow equations, yielding normalisable results consistent with infrared effective theory.
-
The Graviton Propagator in Asymptotically Safe Gravity with Non-Local Form Factors
At quadratic order in asymptotically safe gravity, the graviton propagator has a single pole at q²=0 with positive residue, no ghost poles, and yields a regular Newtonian potential at r=0.
-
Asymptotically Safe Gravitational Form Factors from the Proper-Time Flow Equation
Asymptotically safe gravitational form factors are obtained by integrating the proper-time flow to k=0; finite cutoff-independent results with 1/q² UV decay require selecting the non-Gaussian fixed point as UV boundar...
-
Scaling solutions for gauge invariant flow equations in dilaton quantum gravity
Scaling solutions of a gauge-invariant functional flow equation support the dilaton quantum gravity fixed point, with Planck mass ~ φ² at large field and a stable negative kinetial in the infrared.
-
Towards theory constraints on ultralight dark matter from quantum gravity
In asymptotically safe gravity, dimension-five couplings of ultralight scalar dark matter to gauge field strengths vanish and are not generated perturbatively.
-
Impact of quantum gravity on the UV sensitivity of extremal black holes
Asymptotically safe quantum gravity predicts a positive Goroff-Sagnotti Wilson coefficient at the Planck scale, which would keep extremal Kerr black hole tidal forces finite, but the paper's bound on the quantum gravi...
-
Self-consistent graviton spectral function in Lorentzian quantum gravity
A self-consistent spectral renormalisation group computation yields a positive, normalizable graviton spectral function with a massless pole and a multi-graviton continuum decaying as 1/(λ² log³ λ²).
-
The pole truth: an analytical graviton propagator from Asymptotic Safety
Analytical approximation to the graviton propagator from Asymptotic Safety shows no extra poles and identifies a mechanism where spurious pole residues vanish at higher orders.
-
Asymptotically safe quantum gravity and its phenomenology -- a review
Review surveying progress toward realistic asymptotically safe quantum gravity with quantum scale symmetry and observational implications.
Reference graph
Works this paper leans on
-
[35]
(see also [ 116]). In a related vein, it has also been noted that a general regulator Rk(p2) is not compatible with gauge invariance in the sense that it requires the introduction of modified Ward or Slavnov-Taylor identi- ties [102, 117], and that it interferes with the structure of thermal fluctuations [ 118]. Interestingly, either of these aspects are ...
-
[1]
Weinberg, Ultraviolet divergences in quantum theories of gravitation , pp
S. Weinberg, Ultraviolet divergences in quantum theories of gravitation , pp. 790–831. 1980
1980
-
[2]
Reuter, Nonperturbative evolution equation for quantum gravity, Phys
M. Reuter, Nonperturbative evolution equation for quantum gravity, Phys. Rev. D 57 (1998) 971 [hep-th/9605030]
arXiv 1998
-
[3]
Souma, Nontrivial ultraviolet fixed point in quantum gravity, Prog.Theor.Phys
W. Souma, Nontrivial ultraviolet fixed point in quantum gravity, Prog.Theor.Phys. 102 (1999) 181 [hep-th/9907027]
arXiv 1999
-
[4]
M. Reuter and F. Saueressig, Renormalization group flow of quantum gravity in the Einstein-Hilbert truncation, Phys. Rev. D65 (2002) 065016 [hep-th/0110054]
arXiv 2002
-
[5]
D. F. Litim, Fixed points of quantum gravity , Phys.Rev.Lett. 92 (2004) 201301 [ hep-th/0312114]
arXiv 2004
-
[6]
P. Fischer and D. F. Litim, Fixed points of quantum gravity in extra dimensions , Phys.Lett. B638 (2006) 497 [hep-th/0602203]
arXiv 2006
-
[7]
E. Manrique, S. Rechenberger and F. Saueressig, Asymptotically Safe Lorentzian Gravity , Phys.Rev.Lett. 106 (2011) 251302 [ 1102.5012]
arXiv 2011
Show all 139 references
-
[8]
Donkin and J
I. Donkin and J. M. Pawlowski, The phase diagram of quantum gravity from diffeomorphism-invariant RG-flows, 1203.4207
-
[9]
Falls, Physical renormalization schemes and asymptotic safety in quantum gravity , Phys
K. Falls, Physical renormalization schemes and asymptotic safety in quantum gravity , Phys. Rev. D96 (2017) 126016 [ 1702.03577]
2017 arXiv
-
[10]
Baldazzi and K
A. Baldazzi and K. Falls, Essential Quantum Einstein Gravity, Universe 7 (2021) 294 [ 2107.00671]
2021 arXiv
-
[11]
Kluth, Fixed points of quantum gravity from dimensional regularization, Phys
Y. Kluth, Fixed points of quantum gravity from dimensional regularization, Phys. Rev. D 111 (2025) 106010 [2409.09252]
2025 arXiv
-
[12]
Codello, R
A. Codello, R. Percacci and C. Rahmede, Ultraviolet properties of f(R)-gravity, Int. J. Mod. Phys. A23 (2008) 143 [ 0705.1769]
2008 arXiv
-
[13]
P. F. Machado and F. Saueressig, On the renormalization group flow of f(R)-gravity , Phys. Rev. D77 (2008) 124045 [ 0712.0445]
2008 arXiv
-
[14]
M. R. Niedermaier, Gravitational Fixed Points from Perturbation Theory, Phys. Rev. Lett. 103 (2009) 101303
2009
-
[15]
Falls, D
K. Falls, D. Litim, K. Nikolakopoulos and C. Rahmede, A bootstrap towards asymptotic safety , 1301.4191
-
[16]
Falls, D
K. Falls, D. F. Litim, K. Nikolakopoulos and C. Rahmede, Further evidence for asymptotic safety of quantum gravity, Phys. Rev. D93 (2016) 104022 [1410.4815]
2016 arXiv
-
[17]
H. Gies, B. Knorr, S. Lippoldt and F. Saueressig, Gravitational Two-Loop Counterterm Is Asymptotically Safe, Phys. Rev. Lett. 116 (2016) 211302 [ 1601.01800]
2016 arXiv
-
[18]
Falls, D
K. Falls, D. F. Litim, K. Nikolakopoulos and C. Rahmede, On de Sitter solutions in asymptotically safe f (R) theories, Class. Quant. Grav. 35 (2018) 135006 [1607.04962]
2018 arXiv
-
[19]
Falls, C
K. Falls, C. R. King, D. F. Litim, K. Nikolakopoulos and C. Rahmede, Asymptotic safety of quantum gravity beyond Ricci scalars, Phys. Rev. D97 (2018) 086006 [1801.00162]
2018 arXiv
-
[20]
Christiansen, K
N. Christiansen, K. Falls, J. M. Pawlowski and M. Reichert, Curvature dependence of quantum gravity , Phys. Rev. D 97 (2018) 046007 [ 1711.09259]
2018 arXiv
-
[21]
K. G. Falls, D. F. Litim and J. Schr¨ oder,Aspects of asymptotic safety for quantum gravity , Phys. Rev. D 99 (2019) 126015 [ 1810.08550]
2019 arXiv
-
[22]
Kluth and D
Y. Kluth and D. F. Litim, Fixed points of quantum gravity and the dimensionality of the UV critical surface, Phys. Rev. D 108 (2023) 026005 [ 2008.09181]
2023 arXiv
-
[23]
Falls, N
K. Falls, N. Ohta and R. Percacci, Towards the determination of the dimension of the critical surface in asymptotically safe gravity , Phys. Lett. B 810 (2020) 135773 [2004.04126]
2020 arXiv
-
[24]
Knorr, The derivative expansion in asymptotically safe quantum gravity: general setup and quartic order , SciPost Phys
B. Knorr, The derivative expansion in asymptotically safe quantum gravity: general setup and quartic order , SciPost Phys. Core 4 (2021) 020 [ 2104.11336]
2021 arXiv
-
[25]
T. R. Morris and D. Stulga, The Functional f(R) Approximation, in Handbook of Quantum Gravity , (Singapore), pp. 1–33, Springer Nature Singapore, (2023), 2210.11356, DOI
2023 arXiv
-
[26]
Kluth and D
Y. Kluth and D. F. Litim, Functional renormalization for f(R µνρσ ) quantum gravity , Phys. Rev. D 106 (2022) 106022 [2202.10436]
2022 arXiv
-
[27]
Baldazzi, K
A. Baldazzi, K. Falls, Y. Kluth and B. Knorr, Robustness of the derivative expansion in Asymptotic Safety, 2312.03831
-
[28]
Falls and R
K. Falls and R. Ferrero, Asymptotic Safety within on-shell perturbation theory , 2411.00938
-
[29]
Christiansen, D
N. Christiansen, D. F. Litim, J. M. Pawlowski and A. Rodigast, Fixed points and infrared completion of quantum gravity, Phys. Lett. B 728 (2014) 114 17 [1209.4038]
2014 arXiv
-
[30]
Christiansen, B
N. Christiansen, B. Knorr, J. M. Pawlowski and A. Rodigast, Global Flows in Quantum Gravity , Phys. Rev. D 93 (2016) 044036 [ 1403.1232]
2016 arXiv
-
[31]
Christiansen, B
N. Christiansen, B. Knorr, J. Meibohm, J. M. Pawlowski and M. Reichert, Local Quantum Gravity, Phys. Rev. D 92 (2015) 121501 [ 1506.07016]
2015 arXiv
-
[32]
T. Denz, J. M. Pawlowski and M. Reichert, Towards apparent convergence in asymptotically safe quantum gravity, Eur. Phys. J. C 78 (2018) 336 [ 1612.07315]
2018 arXiv
-
[33]
Knorr and M
B. Knorr and M. Schiffer, Non-Perturbative Propagators in Quantum Gravity , Universe 7 (2021) 216 [2105.04566]
2021 arXiv
-
[34]
Bonanno, T
A. Bonanno, T. Denz, J. M. Pawlowski and M. Reichert, Reconstructing the graviton, SciPost Phys. 12 (2022) 001 [ 2102.02217]
2022 arXiv
-
[36]
D. F. Litim, Fixed Points of Quantum Gravity and the Renormalisation Group, 0810.3675
-
[37]
Fehre, D
J. Fehre, D. F. Litim, J. M. Pawlowski and M. Reichert, Lorentzian Quantum Gravity and the Graviton Spectral Function, Phys. Rev. Lett. 130 (2023) 081501 [2111.13232]
2023 arXiv
-
[38]
Bonanno, A
A. Bonanno, A. Eichhorn, H. Gies, J. M. Pawlowski, R. Percacci, M. Reuter et al., Critical reflections on asymptotically safe gravity , Front. in Phys. 8 (2020) 269 [2004.06810]
2020 arXiv
-
[39]
Hindmarsh, D
M. Hindmarsh, D. Litim and C. Rahmede, Asymptotically Safe Cosmology , JCAP 07 (2011) 019 [1101.5401]
2011 arXiv
-
[40]
Reuter and F
M. Reuter and F. Saueressig, Quantum Gravity and the Functional Renormalization Group: The Road towards Asymptotic Safety . Cambridge University Press, 1, 2019
2019
-
[41]
A. D. Pereira, Quantum spacetime and the renormalization group: Progress and visions , in Progress and Visions in Quantum Theory in View of Gravity: Bridging foundations of physics and mathematics , 4, 2019, 1904.07042
2019 arXiv
-
[42]
Platania, From renormalization group flows to cosmology, Front
A. Platania, From renormalization group flows to cosmology, Front. in Phys. 8 (2020) 188 [ 2003.13656]
2020 arXiv
-
[43]
Reichert, Lecture notes: Functional Renormalisation Group and Asymptotically Safe Quantum Gravity , PoS 384 (2020) 005
M. Reichert, Lecture notes: Functional Renormalisation Group and Asymptotically Safe Quantum Gravity , PoS 384 (2020) 005
2020
-
[44]
Knorr, C
B. Knorr, C. Ripken and F. Saueressig, Form Factors in Asymptotically Safe Quantum Gravity , in Handbook of Quantum Gravity, (Singapore), Springer Nature Singapore, (2023), 2210.16072, DOI
2023 arXiv
-
[45]
J. M. Pawlowski and M. Reichert, Quantum Gravity: A Fluctuating Point of View , Front. in Phys. 8 (2021) 551848 [2007.10353]
2021 arXiv
-
[46]
Platania, Black holes in asymptotically safe gravity , in Handbook of Quantum Gravity , (Singapore), Springer Nature Singapore, (2023), 2302.04272, DOI
A. Platania, Black holes in asymptotically safe gravity , in Handbook of Quantum Gravity , (Singapore), Springer Nature Singapore, (2023), 2302.04272, DOI
2023 arXiv
-
[47]
Eichhorn and M
A. Eichhorn and M. Schiffer, Asymptotic safety of gravity with matter , in Handbook of Quantum Gravity , (Singapore), Springer Nature Singapore, (12, 2024), 2212.07456, DOI
2024 arXiv
-
[48]
Don` a, A
P. Don` a, A. Eichhorn and R. Percacci,Matter matters in asymptotically safe quantum gravity , Phys. Rev. D 89 (2014) 084035 [ 1311.2898]
2014 arXiv
-
[49]
J. M. Pawlowski and M. Reichert, Quantum Gravity from dynamical metric fluctuations , in Handbook of Quantum Gravity, (Singapore), Springer Nature Singapore, (9, 2023), 2309.10785, DOI
2023 arXiv
-
[50]
Eichhorn, S
A. Eichhorn, S. Lippoldt and V. Skrinjar, Nonminimal hints for asymptotic safety , Phys. Rev. D 97 (2018) 026002 [1710.03005]
2018 arXiv
-
[51]
Meibohm, J
J. Meibohm, J. M. Pawlowski and M. Reichert, Asymptotic safety of gravity-matter systems , Phys. Rev. D 93 (2016) 084035 [ 1510.07018]
2016 arXiv
-
[52]
Eichhorn, S
A. Eichhorn, S. Lippoldt, J. M. Pawlowski, M. Reichert and M. Schiffer, How perturbative is quantum gravity? , Phys. Lett. B 792 (2019) 310 [ 1810.02828]
2019 arXiv
-
[53]
Eichhorn, P
A. Eichhorn, P. Labus, J. M. Pawlowski and M. Reichert, Effective universality in quantum gravity , SciPost Phys. 5 (2018) 031 [ 1804.00012]
2018 arXiv
-
[54]
Folkerts, D
S. Folkerts, D. F. Litim and J. M. Pawlowski, Asymptotic freedom of Yang-Mills theory with gravity , Phys. Lett. B 709 (2012) 234 [ 1101.5552]
2012 arXiv
-
[55]
Eichhorn, S
A. Eichhorn, S. Lippoldt and M. Schiffer, Zooming in on fermions and quantum gravity , Phys. Rev. D 99 (2019) 086002 [ 1812.08782]
2019 arXiv
-
[56]
Eichhorn and F
A. Eichhorn and F. Versteegen, Upper bound on the Abelian gauge coupling from asymptotic safety , JHEP 01 (2018) 030 [ 1709.07252]
2018 arXiv
-
[57]
Eichhorn, A
A. Eichhorn, A. Held and J. M. Pawlowski, Quantum-gravity effects on a Higgs-Yukawa model , Phys. Rev. D 94 (2016) 104027 [ 1604.02041]
2016 arXiv
-
[58]
Christiansen, D
N. Christiansen, D. F. Litim, J. M. Pawlowski and M. Reichert, Asymptotic safety of gravity with matter , Phys. Rev. D 97 (2018) 106012 [ 1710.04669]
2018 arXiv
-
[59]
Christiansen and A
N. Christiansen and A. Eichhorn, An asymptotically safe solution to the U(1) triviality problem , Phys. Lett. B 770 (2017) 154 [ 1702.07724]
2017 arXiv
-
[60]
J. M. Pawlowski, M. Reichert, C. Wetterich and M. Yamada, Higgs scalar potential in asymptotically safe quantum gravity , Phys. Rev. D 99 (2019) 086010 [1811.11706]
2019 arXiv
-
[61]
Eichhorn and A
A. Eichhorn and A. Held, Viability of quantum-gravity induced ultraviolet completions for matter , Phys. Rev. D 96 (2017) 086025 [ 1705.02342]
2017 arXiv
-
[62]
Shaposhnikov and C
M. Shaposhnikov and C. Wetterich, Asymptotic safety of gravity and the Higgs boson mass , Phys. Lett. B 683 (2010) 196 [ 0912.0208]
2010 arXiv
-
[63]
B¨ urger, J
B. B¨ urger, J. M. Pawlowski, M. Reichert and B.-J. Schaefer, Curvature dependence of quantum gravity with scalars, 1912.01624
1912 arXiv
-
[64]
Eichhorn and A
A. Eichhorn and A. Held, Mass difference for charged quarks from asymptotically safe quantum gravity , Phys. Rev. Lett. 121 (2018) 151302 [ 1803.04027]
2018 arXiv
-
[65]
Eichhorn and A
A. Eichhorn and A. Held, Top mass from asymptotic safety, Phys. Lett. B 777 (2018) 217 [ 1707.01107]
2018 arXiv
-
[66]
D. F. Litim and T. Plehn, Signatures of gravitational fixed points at the LHC , Phys.Rev.Lett. 100 (2008) 131301 [0707.3983]
2008 arXiv
-
[67]
Pastor-Guti´ errez, J
A. Pastor-Guti´ errez, J. M. Pawlowski and M. Reichert, The Asymptotically Safe Standard Model: From quantum gravity to dynamical chiral symmetry breaking , SciPost Phys. 15 (2023) 105 [ 2207.09817]
2023 arXiv
-
[68]
D. F. Litim, Renormalisation group and the Planck scale, Phil.Trans.Roy.Soc.Lond.A369 (2011) 2759 [1102.4624]
2011 arXiv
-
[69]
Gerwick, D
E. Gerwick, D. Litim and T. Plehn, Asymptotic safety and Kaluza-Klein gravitons at the LHC , Phys.Rev. D83 (2011) 084048 [ 1101.5548]
2011 arXiv
-
[70]
Eichhorn and M
A. Eichhorn and M. Pauly, Safety in darkness: Higgs 18 portal to simple Yukawa systems , Phys. Lett. B 819 (2021) 136455 [ 2005.03661]
2021 arXiv
-
[71]
Reichert and J
M. Reichert and J. Smirnov, Dark Matter meets Quantum Gravity, Phys. Rev. D 101 (2020) 063015 [1911.00012]
2020 arXiv
-
[72]
Kowalska and E
K. Kowalska and E. M. Sessolo, Minimal models for g-2 and dark matter confront asymptotic safety , Phys. Rev. D 103 (2021) 115032 [ 2012.15200]
2021 arXiv
-
[73]
Eichhorn and M
A. Eichhorn and M. Pauly, Constraining power of asymptotic safety for scalar fields , Phys. Rev. D 103 (2021) 026006 [ 2009.13543]
2021 arXiv
-
[74]
Baldazzi, R
A. Baldazzi, R. Percacci and V. Skrinjar, Wicked metrics, Class. Quant. Grav. 36 (2019) 105008 [1811.03369]
2019 arXiv
-
[75]
G. P. de Brito, A. Eichhorn, M. T. Frandsen, M. Rosenlyst, M. E. Thing and A. F. Vieira, Ruling out models of vector dark matter in asymptotically safe quantum gravity, Phys. Rev. D 109 (2024) 055022 [2312.02086]
2024 arXiv
-
[76]
Rechenberger and F
S. Rechenberger and F. Saueressig, A functional renormalization group equation for foliated spacetimes , JHEP 03 (2013) 010 [ 1212.5114]
2013 arXiv
-
[77]
Baldazzi, R
A. Baldazzi, R. Percacci and V. Skrinjar, Quantum fields without Wick rotation , Symmetry 11 (2019) 373 [1901.01891]
2019 arXiv
-
[78]
Biemans, A
J. Biemans, A. Platania and F. Saueressig, Renormalization group fixed points of foliated gravity-matter systems, JHEP 05 (2017) 093 [1702.06539]
2017 arXiv
-
[79]
Biemans, A
J. Biemans, A. Platania and F. Saueressig, Quantum gravity on foliated spacetimes: Asymptotically safe and sound, Phys. Rev. D95 (2017) 086013 [ 1609.04813]
2017 arXiv
-
[80]
Eichhorn, A
A. Eichhorn, A. Platania and M. Schiffer, Lorentz invariance violations in the interplay of quantum gravity with matter , Phys. Rev. D 102 (2020) 026007 [1911.10066]
2020 arXiv
-
[81]
Knorr, Lorentz symmetry is relevant , Phys
B. Knorr, Lorentz symmetry is relevant , Phys. Lett. B 792 (2019) 142 [ 1810.07971]
2019 arXiv
-
[82]
Saueressig and J
F. Saueressig and J. Wang, Foliated asymptotically safe gravity in the fluctuation approach , JHEP 09 (2023) 064 [2306.10408]
2023 arXiv
-
[83]
Knorr, A
B. Knorr, A. Platania and M. Schiffer, Configuration space for quantum gravity in a locally regularized path integral, Phys. Rev. D 106 (2022) 126002 [ 2205.13558]
2022 arXiv
-
[84]
Saueressig and J
F. Saueressig and J. Wang, Foliated asymptotically safe gravity: Lorentzian signature fluctuations from the Wick rotation, Phys. Rev. D 111 (2025) 106007 [ 2501.03752]
2025 arXiv
-
[85]
Korver, F
G. Korver, F. Saueressig and J. Wang, Global flows of foliated gravity-matter systems , Phys. Lett. B 855 (2024) 138789 [ 2402.01260]
2024 arXiv
-
[86]
Knorr and C
B. Knorr and C. Ripken, Scattering amplitudes in affine gravity, Phys. Rev. D 103 (2021) 105019 [ 2012.05144]
2021 arXiv
-
[87]
Draper, B
T. Draper, B. Knorr, C. Ripken and F. Saueressig, Finite Quantum Gravity Amplitudes: No Strings Attached, Phys. Rev. Lett. 125 (2020) 181301 [2007.00733]
2020 arXiv
-
[88]
Pastor-Guti´ errez, J
A. Pastor-Guti´ errez, J. M. Pawlowski, M. Reichert and G. Ruisi, e+e-→µ+µ- in the asymptotically safe standard model, Phys. Rev. D 111 (2025) 106005 [2412.13800]
2025 arXiv
-
[89]
Knorr, S
B. Knorr, S. Pirlo, C. Ripken and F. Saueressig, Cartographing gravity-mediated scattering amplitudes: scalars and photons , 2205.01738
-
[90]
Platania, Causality, unitarity and stability in quantum gravity: a non-perturbative perspective , JHEP 09 (2022) 167 [ 2206.04072]
A. Platania, Causality, unitarity and stability in quantum gravity: a non-perturbative perspective , JHEP 09 (2022) 167 [ 2206.04072]
2022 arXiv
-
[91]
Platania and C
A. Platania and C. Wetterich, Non-perturbative unitarity and fictitious ghosts in quantum gravity , Phys. Lett. B 811 (2020) 135911 [ 2009.06637]
2020 arXiv
-
[92]
Eichhorn, A
A. Eichhorn, A. O. Pedersen and M. Schiffer, Application of positivity bounds in asymptotically safe gravity, 2405.08862
-
[93]
Knorr and A
B. Knorr and A. Platania, Unearthing the intersections: positivity bounds, weak gravity conjecture, and asymptotic safety landscapes from photon-graviton flows , JHEP 03 (2025) 003 [ 2405.08860]
2025 arXiv
-
[94]
D’Angelo, N
E. D’Angelo, N. Drago, N. Pinamonti and K. Rejzner, An Algebraic QFT Approach to the Wetterich Equation on Lorentzian Manifolds , Annales Henri Poincare 25 (2024) 2295 [ 2202.07580]
2024 arXiv
-
[95]
Buoninfante et al., Visions in Quantum Gravity , 2412.08696
L. Buoninfante et al., Visions in Quantum Gravity , 2412.08696
-
[96]
D’Angelo and K
E. D’Angelo and K. Rejzner, A Lorentzian renormalisation group equation for gauge theories , Annales Henri Poincar´ e(2025) 1424 [ 2303.01479]
2025 arXiv
-
[97]
Banerjee and M
R. Banerjee and M. Niedermaier, The spatial Functional Renormalization Group and Hadamard states on cosmological spacetimes, Nucl. Phys. B 980 (2022) 115814 [ 2201.02575]
2022 arXiv
-
[98]
Banerjee and M
R. Banerjee and M. Niedermaier, Wick rotation in the lapse, admissible complex metrics, and foliation changing diffeomorphisms, Class. Quant. Grav. 42 (2025) 095003 [ 2406.06047]
2025 arXiv
-
[99]
D’Angelo, Asymptotic safety in Lorentzian quantum gravity, Phys
E. D’Angelo, Asymptotic safety in Lorentzian quantum gravity, Phys. Rev. D 109 (2024) 066012 [ 2310.20603]
2024 arXiv
-
[100]
Ferrero and T
R. Ferrero and T. Thiemann, Relational Lorentzian Asymptotically Safe Quantum Gravity: Showcase Model , Universe 10 (2024) 410 [ 2404.18224]
2024 arXiv
-
[101]
Thiemann, Asymptotically safe — canonical quantum gravity junction, JHEP 10 (2024) 013 [ 2404.18220]
T. Thiemann, Asymptotically safe — canonical quantum gravity junction, JHEP 10 (2024) 013 [ 2404.18220]
2024 arXiv
-
[102]
D. F. Litim and J. M. Pawlowski, On gauge invariant Wilsonian flows , hep-th/9901063
-
[103]
D’Angelo, R
E. D’Angelo, R. Ferrero and M. B. Fr¨ ob,De sitter quantum gravity within the covariant lorentzian approach to asymptotic safety , Classical and Quantum Gravity 42 (2025) 125008 [ 2502.05135]
2025 arXiv
-
[104]
D. J. E. Callaway, Triviality Pursuit: Can Elementary Scalar Particles Exist? , Phys. Rept. 167 (1988) 241
1988
-
[105]
D. F. Litim and J. M. Pawlowski, Non-perturbative thermal flows and resummations , JHEP 0611 (2006) 026 [hep-th/0609122]
2006 arXiv
-
[106]
King, Quantum gravitational influence to scalar matter systems , Master’s thesis, University of Sussex, 2024
B. King, Quantum gravitational influence to scalar matter systems , Master’s thesis, University of Sussex, 2024
2024
-
[107]
Kher, Interplay between quantum gravity and photons within the asymptotic safety scenario , Master’s thesis, University of Sussex, 2024
V. Kher, Interplay between quantum gravity and photons within the asymptotic safety scenario , Master’s thesis, University of Sussex, 2024
2024
-
[108]
Gies and S
H. Gies and S. Lippoldt, Fermions in gravity with local spin-base invariance, Phys. Rev. D 89 (2014) 064040 [1310.2509]
2014 arXiv
-
[109]
H. A. Weldon, Fermions without vierbeins in curved space-time, Phys. Rev. D 63 (2001) 104010 [gr-qc/0009086]
2001 arXiv
-
[110]
Kallen, On the definition of the Renormalization Constants in Quantum Electrodynamics , Helv
G. Kallen, On the definition of the Renormalization Constants in Quantum Electrodynamics , Helv. Phys. Acta 25 (1952) 417
1952
-
[111]
Lippoldt, Spin-base invariance of Fermions in arbitrary dimensions, Phys
S. Lippoldt, Spin-base invariance of Fermions in arbitrary dimensions, Phys. Rev. D 91 (2015) 104006 [1502.05607]
2015 arXiv
-
[112]
quenched
but with the inclusion of a running counter-term action ∂tSct,k[Φ]. Therefore, the spectral RG equation is given by [35, 116], ∂tΓk[Φ] = 1 2 TrGk[Φ] ∂tRk − ∂tSct,k[Φ] . (11) Here, the RG time is defined as t = ln k/kref where kref is some reference scale. The full field- and s...
-
[113]
Lehmann, On the Properties of propagation functions and renormalization contants of quantized 19 fields, Nuovo Cim
H. Lehmann, On the Properties of propagation functions and renormalization contants of quantized 19 fields, Nuovo Cim. 11 (1954) 342
1954
-
[114]
Wetterich, Exact evolution equation for the effective potential, Phys
C. Wetterich, Exact evolution equation for the effective potential, Phys. Lett. B 301 (1993) 90 [ 1710.05815]
1993 arXiv
-
[115]
T. R. Morris, The Exact renormalization group and approximate solutions, Int. J. Mod. Phys. A 9 (1994) 2411 [hep-ph/9308265]
1994 arXiv
-
[116]
Ellwanger, FLow equations for N point functions and bound states, Z
U. Ellwanger, FLow equations for N point functions and bound states, Z. Phys. C 62 (1994) 503 [hep-ph/9308260]
1994 arXiv
-
[117]
D. F. Litim, Optimization of the exact renormalization group, Phys.Lett. B486 (2000) 92 [ hep-th/0005245]
2000 arXiv
-
[118]
Braun et al., Renormalised spectral flows, SciPost Phys
J. Braun et al., Renormalised spectral flows, SciPost Phys. Core 6 (2023) 061 [ 2206.10232]
2023 arXiv
-
[119]
Freire, D
F. Freire, D. F. Litim and J. M. Pawlowski, Gauge invariance and background field formalism in the exact renormalization group, Phys.Lett. B495 (2000) 256 [hep-th/0009110]
2000 arXiv
-
[120]
D. F. Litim, Optimized renormalization group flows , Phys. Rev. D 64 (2001) 105007 [ hep-th/0103195]
2001 arXiv
-
[121]
Horak, J
J. Horak, J. M. Pawlowski and N. Wink, Spectral functions in the ϕ4-theory from the spectral DSE , Phys. Rev. D 102 (2020) 125016 [ 2006.09778]
2020 arXiv
-
[122]
Horak, J
J. Horak, J. Papavassiliou, J. M. Pawlowski and N. Wink, Ghost spectral function from the spectral Dyson-Schwinger equation, Phys. Rev. D 104 (2021) 074017 [2103.16175]
2021 arXiv
-
[123]
Horak, J
J. Horak, J. M. Pawlowski and N. Wink, On the complex structure of Yang-Mills theory , 2202.09333
-
[124]
Buttazzo, G
D. Buttazzo, G. Degrassi, P. P. Giardino, G. F. Giudice, F. Sala, A. Salvio et al., Investigating the near-criticality of the Higgs boson , JHEP 12 (2013) 089 [ 1307.3536]
2013 arXiv
-
[125]
J.-E. Daum, U. Harst and M. Reuter, Running Gauge Coupling in Asymptotically Safe Quantum Gravity , JHEP 1001 (2010) 084 [ 0910.4938]
2010 arXiv
- [126]
-
[127]
Eichhorn and M
A. Eichhorn and M. Schiffer, d = 4 as the critical dimensionality of asymptotically safe interactions , Phys. Lett. B 793 (2019) 383 [ 1902.06479]
2019 arXiv
-
[128]
G. P. de Brito and A. Eichhorn, Nonvanishing gravitational contribution to matter beta functions for vanishing dimensionful regulators , Eur. Phys. J. C 83 (2023) 161 [ 2201.11402]
2023 arXiv
-
[129]
Zanusso, L
O. Zanusso, L. Zambelli, G. P. Vacca and R. Percacci, Gravitational corrections to Yukawa systems , Phys. Lett. B689 (2010) 90 [ 0904.0938]
2010 arXiv
-
[130]
Oda and M
K.-y. Oda and M. Yamada, Non-minimal coupling in Higgs–Yukawa model with asymptotically safe gravity , Class. Quant. Grav. 33 (2016) 125011 [ 1510.03734]
2016 arXiv
-
[131]
de Brito, M
G. de Brito, M. Reichert and M. Schiffer in preparation
-
[132]
J. M. Mart ´ ın-Garc ´ ıa,xPerm: fast index canonicalization for tensor computer algebra , Comput. Phys. Commun. 179 (2008) 597 [ 0803.0862]
2008 arXiv
-
[133]
Brizuela, J
D. Brizuela, J. M. Martin-Garcia and G. A. Mena Marugan, xPert: Computer algebra for metric perturbation theory, Gen. Rel. Grav. 41 (2009) 2415 [0807.0824]
2009 arXiv
-
[134]
Huber and D
T. Huber and D. Maitre, HypExp: A Mathematica package for expanding hypergeometric functions around integer-valued parameters, Comput. Phys. Commun. 175 (2006) 122 [ hep-ph/0507094]
2006 arXiv
-
[135]
Kluth, D
Y. Kluth, D. F. Litim and M. Reichert, Spectral functions of gauge theories with Banks-Zaks fixed points , Phys. Rev. D 107 (2023) 025011 [ 2207.14510]
2023 arXiv
-
[136]
Bosma, B
L. Bosma, B. Knorr and F. Saueressig, Resolving Spacetime Singularities within Asymptotic Safety , Phys. Rev. Lett. 123 (2019) 101301 [ 1904.04845]
2019 arXiv
-
[137]
Knorr, C
B. Knorr, C. Ripken and F. Saueressig, Form Factors in Asymptotic Safety: conceptual ideas and computational toolbox, Class. Quant. Grav. 36 (2019) 234001 [1907.02903]
2019 arXiv
-
[138]
Draper, B
T. Draper, B. Knorr, C. Ripken and F. Saueressig, Graviton-Mediated Scattering Amplitudes from the Quantum Effective Action , JHEP 11 (2020) 136 [2007.04396]
2020 arXiv
-
[139]
J. M. Pawlowski and J. Tr¨ ankle,Effective action and black hole solutions in asymptotically safe quantum gravity, Phys. Rev. D 110 (2024) 086011 [ 2309.17043]
2024 arXiv
Reviewed August 6, 2026 · model on record in the stance chip above.
Discussion (0). Sign in to comment.