REVIEW 3 major objections 4 minor 2 cited by
Quantifying the accuracy of the Alcock-Paczynski scaling of baryon acoustic oscillation measurements
T0 review · 3 major / 4 minor · reviewed 2026-08-14 · deepseek-v4-flash
Pith's one-line read This paper claims that the standard constant AP scaling of BAO measurements is accurate only when fiducial and true metric gradients are comparable, and that replacing the scaling parameters by their survey averages is more accurate; it…
desk verdict A careful, genuinely useful BAO systematics paper: the new survey-averaged AP scaling and the ~1% residual deserve referee time, though the residual's origin is not fully pinned down. 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 engine of the argument is the small-separation geodesic distance approximation $D_T^2 \approx g_{zz}(\delta z)^2 + g_{\theta\theta}(\delta\Theta)^2$, which lets any spherically-symmetric template metric be parametrised relative to a fiducial one by the redshift-dependent AP functions $\alpha(z)$ and $\epsilon(z)$. From these, the paper constructs the exact redshift-dependent map of the 2-point correlation function and its wedge integrals, then expands the redshift average to first order; this expansion identifies the survey-averaged parameters $\bar\alpha$ and $\bar\epsilon$ as the correct constant parameters. The empirical Gaussian-plus-polynomial model of the BAO feature, fitted to the mean correlation function of mock catalogues, converts the analytic predictions into measured peak shifts and warping parameters.
What would settle it
Recompute the 'exact' redshift-dependent AP predictions for the toy models $D(z)[1 + A\cos(f z + \Phi)]$ using full geodesic distances rather than the local-metric approximation. If the resulting BAO peak shifts differ from the paper's benchmark by more than about $0.1\%$ at separations near $100\,\mathrm{Mpc}/h$ for the $f = 30$ and $f = 50$ cases, then the benchmark itself is approximate and the stated accuracy of the modified AP scaling for all test models is not established.
Extended reading notes
Core claim
The paper's central claim is that the conventional constant Alcock–Paczyński approximation, which takes the two scaling functions at the survey's mean redshift, is only a special case of a more accurate constant choice: the survey-averaged values. In the spherically-symmetric template framework, a first-order expansion of the redshift-integrated correlation function identifies the survey-averaged parameters as the ones that enter the effective BAO template. On mock catalogues the two choices are nearly indistinguishable for smooth large-scale cosmologies, but the modified choice remains accurate for toy models with large metric oscillations where the conventional choice fails. The paper also finds a residual systematic error of about 1% in the recovered BAO scale when the true model differs from the fiducial by roughly ten percent in its distance measures, present even when the exact redshift-dependent AP functions are used, and similar for both the empirical Gaussian fit and the standard template fit; it therefore presents this as a systematic that must be added to the error budget when BAO distances are extrapolated beyond the fiducial cosmology.
Load-bearing premise
The load-bearing premise is the small-separation approximation that treats the distance between galaxy pairs as if the metric components were constant across the pair; the paper verifies it for FLRW and timescape models but applies it without independent verification to the high-frequency toy models where the metric oscillates on scales comparable to the pair separation.
Editorial extensions
If this is right
- Published constant AP parameters from BAO analyses should be read as survey-averaged distance ratios, not as values at a single effective redshift.
- For pairs of smooth large-scale cosmologies the conventional constant AP approximation is adequate, so existing concordance-model results do not need to be redone.
- When a BAO measurement is used to constrain a model whose distance measures differ from the fiducial by about ten percent, a systematic error of roughly one percent in the acoustic scale should be added to the error budget.
- The modified AP scaling can be applied to existing analyses by reinterpreting their fitted parameters, which matters for models with significant curvature gradients.
- The standard approach breaks down when the true metric has large gradients relative to a smooth fiducial metric; in such cases evaluating AP parameters at the mean redshift misstates the effective distance ratios.
Reading between the lines
- The same Taylor-expansion argument suggests the survey-averaging correction applies to any redshift-dependent distance scale fitted through a correlation-function wedge, so the reinterpretation of AP parameters may carry over to other clustering statistics.
- Because the ~1% residual appears even with exact redshift-dependent scaling, BAO-only constraints on models far from the fiducial cosmology are limited by a systematic of the same order as current statistical errors; combining probes reduces statistics, not this model-dependence.
- A natural testable extension is to reverse the roles of true and fiducial models in the toy-model mock analysis; the paper expects its conclusions to hold under reversal but does not demonstrate it.
- If the local-metric approximation fails for the high-frequency toy models, both the conventional and modified constant AP methods inherit the same benchmark error, so the modified method's reported advantage in those cases would need to be re-evaluated.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper investigates the validity of the conventional constant Alcock-Paczyński (AP) scaling used in baryon acoustic oscillation (BAO) analyses. It derives analytic bounds on the difference between the standard approximation, in which the AP parameters α and ϵ are evaluated at the survey mean redshift, and a modified approximation in which they are replaced by survey-averaged values ᾱ and ϵ̄. The authors propose that published AP parameters should be reinterpreted as survey-averaged distance ratios, and they test this proposal on QPM mock catalogues for a range of ΛCDM, timescape, and toy-model cosmologies. They report systematic errors of about 1% in the recovery of the BAO scale when the fiducial and true cosmologies are distant, and show that these errors persist when the full redshift-dependent AP functions are used instead of constant parameters and that a similar trend appears with a ΛCDM template fitting procedure.
Significance. If correct, the paper has two significant consequences. First, the constant AP parameters reported in the literature are more accurately interpreted as survey-averaged ratios rather than values at a single effective redshift; this matters for models with large metric gradients. Second, BAO-derived distance measurements carry a model-dependent systematic at the percent level when extrapolated beyond the fiducial cosmology, a systematic that is not captured by the constant-AP approximation itself. The analytic bounds in Eqs. (3.9) and (3.14) are parameter-free and useful, the mock tests use 200–1000 QPM catalogues with estimated covariance, and the ΛCDM template cross-check provides a nontrivial robustness test. The main limitations are that the residual systematics are not traced to a specific source and that some claims rest on assumptions shared by the two fitting procedures.
major comments (3)
- [Sec. 5.3; Sec. 2.3] The paper's central claim that the ~1% systematic 'cannot be attributed to any constant AP approximation' is supported by comparing fits with constant AP parameters to fits using the redshift-dependent functions (5.8). However, both fitting models assume a redshift-independent BAO scale r and both use the same approximate redshift integral (3.3). Section 2.3 acknowledges that the standard-ruler assumption has shifts below ~0.5% in ΛCDM at z>0.3, which is comparable to the claimed 1% effect at |ᾱ−1|~0.1. The ΛCDM template cross-check fixes the template shape and therefore shares the same standard-ruler assumption. Please quantify the impact of a redshift-dependent BAO scale, for example by fitting with a redshift-dependent r or by using mocks where the BAO scale variation is known, or explicitly scope the abstract and Section 6 claims to the standard-ruler ansatz.
- [Sec. 5.4; Eq. (2.4)] The local-metric approximation (2.4) is verified in Section 2.1 only for FLRW and timescape models. It is then applied without verification to the toy models of Section 5.4, whose distance-redshift relations oscillate as A cos(fz+Φ) with f up to 50. For a radial pair at z≈0.5 with separation 100 Mpc/h, δz≈0.03, so f δz≈1.5 and the metric varies substantially across the pair. In this regime the 'exact' redshift-dependent AP predictions (5.8) used as the benchmark in Figure 7b are themselves approximate, and the statement that the modified constant AP scaling is efficient for all tested models rests on an unvalidated premise. Please verify (2.4) for the toy-model parameters, for instance by direct numerical geodesic integration, or restrict the toy-model conclusions to the regime where (2.4) is accurate.
- [Abstract; Sec. 6] The statement that the level of systematic uncertainty is 'robust to the exact fitting method employed' is stronger than the evidence presented: only two fitting methods are compared, and both use a fixed template or a fixed standard ruler. The evidence supports robustness to the two fitting methods considered. Please rephrase the claim accordingly, or add a third, less parametric BAO extraction method.
minor comments (4)
- [Sec. 5.4] The paragraph following Figure 7a refers to 'figure 3b' when comparing the modified constant AP scaling to the exact AP scaling; this should be 'figure 7b'.
- [Sec. 2.1] The claimed verification that corrections to Eq. (2.4) are below 10^-3 for FLRW and timescape models is stated without quantitative details; please provide the numerical values or a reference to a figure or table.
- [Sec. 5.1] The text says that 1000 QPM mock catalogues are used for the reference model and 200 for the remaining trial cosmologies; please ensure the sample sizes are stated consistently in the figure captions and in the text describing the fits.
- [Introduction] There is a typo in the first paragraph of Section 1: 'use of of N-body mock catalogues' should read 'use of N-body mock catalogues'.
Circularity Check
No significant circularity: claims are benchmarked against mock catalogues with known true cosmology, and the modified AP scaling follows from an explicit Taylor expansion rather than from the data it explains.
full rationale
The paper's central claims are tested against QPM mock catalogues with a known reference cosmology (Omega_M = 0.29), providing an external benchmark for comparing the standard constant AP, modified constant AP, and redshift-dependent 'exact' AP expressions. The modified AP approximation is introduced via the first-order expansion (3.4), where the survey-averaged parameters (bar-alpha, bar-epsilon) are defined by (3.5); the claim that using these averages removes the first-order error is an analytic consequence of Taylor's theorem, not a parameter fitted to the final answer. The bounds (3.9) and (3.14) are derived directly from Taylor remainders and triangle inequalities, without invoking the target result. The residual ~1% systematics are measured relative to the calibrated reference scale r = 102.47 Mpc/h, which is determined from the same mocks; this calibration is a standard device to remove an overall offset, and it does not pre-determine the residual trend as a function of (bar-alpha). The robustness claim is supported by the independent Lambda-CDM-template cross-check (figure 5). Although reference [26] (with overlapping authorship) supplies the empirical fitting model, the model is an explicit ansatz rather than a hidden input, and the key conclusions are confirmed with a different fitting procedure. The unvalidated local-metric approximation for the high-frequency toy models is a correctness concern, not a circular reduction: eq. (5.8) does not reduce to the fitting model by construction, and the toy-model results are not used to justify the theoretical bounds. No fitted parameter is renamed as a prediction, and no load-bearing self-citation chain is present.
Assumptions & free parameters
free parameters (4)
- BAO peak calibration scale r (reference model) =
102.47 Mpc/h
- Empirical model shape parameters (A, σ, C0, C1, C2) =
not quoted in paper
- Toy-model distortion parameters (A, f, Φ) =
A in {0.001, 0.003, 0.005, 0.01}; f in {10, 12, 15, 20, 30, 40, 50}; Φ in {-0.6, -0.3, 0}
- Truncated Gaussian redshift distribution parameters (μ, σ) =
CMASS: μ=0.54, σ=0.075; LOWZ: μ=0.31, σ=0.10
assumptions (4)
- domain assumption The large-scale geometry and galaxy distribution are described by an observer-adapted, spherically-symmetric template metric (2.1)-(2.3), with monotone z(r).
- domain assumption Local geodesic distance approximation (2.4), neglecting second-order variations of the spatial metric over galaxy-pair separations.
- domain assumption Almost multiplicative separability of the pair-count density, f(D,μ,z) ≈ f(D,μ)P(z)(1+δ) with δ and δ_Poisson much less than 1 (A.13), allowing ξ(D,μ) ≈ ∫ dz P(z) ξ(D,μ,z) to first order.
- domain assumption The BAO feature peak is a redshift-independent statistical standard ruler of scale r.
Cite this review
Pith. "Pith review of Quantifying the accuracy of the Alcock-Paczynski scaling of baryon acoustic oscillation measurements." pith.science (2026). https://pith.science/paper/AMEGI2HN
@misc{pith2026190811508,
author = {Pith},
title = {Pith review of: Quantifying the accuracy of the Alcock-Paczynski scaling of baryon acoustic oscillation measurements},
year = {2026},
howpublished = {\url{https://pith.science/paper/AMEGI2HN}},
note = {Machine review of arXiv:1908.11508}
}
abstract
We investigate - in a generic setting - the regime of applicability of the Alcock-Paczynski (AP) scaling conventionally applied to test different cosmological models, given a fiducial measurement of the baryon acoustic oscillation (BAO) characteristic scale in the galaxy 2-point correlation function. We quantify the error in conventional AP scaling methods, for which our ignorance about the true cosmology is parameterised in terms of two constant AP scaling parameters. We propose a new, and as it turns out, improved version of the constant AP scaling, also consisting of two scaling parameters. The two constant AP scaling methods are almost indistinguishable when the fiducial model used in data reduction and the "true" underlying cosmology are not differing substantially in terms of metric gradients, but are otherwise expected to differ. Our new methods can be applied to existing analyses through a reinterpretation of the results of the conventional AP scaling. This reinterpretation might be important in model universes where curvature gradients above the scale of galaxies are significant. We test our theoretical findings on $\Lambda$CDM mock catalogues. The conventional constant AP scaling methods are surprisingly successful for pairs of large-scale metrics, but eventually break down when toy models allowing for large metric gradients are tested. The new constant AP scaling methods proposed in this paper are efficient for all test models examined. We find systematic errors of ~1% in the recovery of the BAO scale when the true model is distant from the fiducial, which cannot be attributed to any constant AP approximation. The level of systematic uncertainty is robust to the exact fitting method employed. This indicates that caution must be taken with the error budget when extrapolating the BAO acoustic scale measurements obtained in the standard literature.
Forward citations
Cited by 2 Pith papers
-
BAO miscalibration cannot rescue late-time solutions to the Hubble tension
Even after rescaling BAO data to prefer H0≈73 km/s/Mpc, none of six tested late-time dark-energy models can resolve the Hubble tension once unanchored SNeIa and CMB geometry are included.
-
Interacting dark energy in the early 2020s: a promising solution to the $H_0$ and cosmic shear tensions
An interacting dark energy model with coupling proportional to the dark energy density alleviates the H0 and S8 tensions in Planck 2018 data but is not preferred once BAO and supernova data are included.
Reference graph
Works this paper leans on
-
[1]
P.J.E. Peebles and J.T. Yu,Primeval Adiabatic Perturbation in an Expanding Universe, Astrophys. J. 162 (1970) 815
work page 1970
-
[2]
R.A. Sunyaev and Ya.B. Zeldovich,Small-Scale Fluctuations of Relic Radiation, Astrophys. Space Sci. 7 (1970) 3
work page 1970
-
[3]
H. J. Seo and D. J. Eisenstein,Probing dark energy with baryonic acoustic oscillations from future large galaxy redshift surveys Astrophys. J.598 (2003) 720 [arXiv:astro-ph/0307460]
arXiv 2003
-
[4]
C. Blake and K. Glazebrook,Probing dark energy using baryonic oscillations in the galaxy power spectrum as a cosmological ruler Astrophys. J.594 (2003) 665 [arXiv:astro-ph/0301632]
arXiv 2003
-
[5]
S. Cole, et al.,The 2dF Galaxy Redshift Survey: Power-spectrum analysis of the final dataset and cosmological implications, Mon. Not. R. Astr. Soc.362 (2005) 505, [astro-ph/0501174]
arXiv 2005
-
[6]
D.J. Eisenstein, et al.,Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies, Astrophys. J. 633 (2005) 560, [astro-ph/0501171]
arXiv 2005
- [7]
-
[8]
S. Alam, et al.,The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample, Mon. Not. R. Astr. Soc. 470 (2017) 2617, [arXiv:1607.03155]
arXiv 2017
Show all 40 references
-
[9]
A. Metin et al.,The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: first measurement of baryon acoustic oscillations between redshift 0.8 and 2.2 Mon. Not. R. Astr. Soc.473 (2018) 4773 [arXiv:1705.06373]
2018 arXiv
-
[10]
Busca, et al.,Baryon acoustic oscillations in the Lyα forest of BOSS quasars, Astron
N.G. Busca, et al.,Baryon acoustic oscillations in the Lyα forest of BOSS quasars, Astron. Astrophys. 552 (2013) A96, [arXiv:1211.2616] – 39 –
2013 arXiv
-
[11]
Delubac et al.,Baryon acoustic oscillations in the Lyα forest of BOSS DR11 quasars, Astron
T. Delubac et al.,Baryon acoustic oscillations in the Lyα forest of BOSS DR11 quasars, Astron. Astrophys. 574 (2015) A59, [arXiv:1404.1801]
2015 arXiv
-
[12]
Wiltshire,Cosmic clocks, cosmic variance and cosmic averages, New J
D.L. Wiltshire,Cosmic clocks, cosmic variance and cosmic averages, New J. Phys.9 (2007) 377, [arXiv:gr-qc/0702082]
2007 arXiv
-
[13]
Wiltshire,Exact solution to the averaging problem in cosmology, Phys
D.L. Wiltshire,Exact solution to the averaging problem in cosmology, Phys. Rev. Lett.99 (2007) 251101, [arXiv:0709.0732]
2007 arXiv
-
[14]
Duley, M.A
J.A.G. Duley, M.A. Nazer and D.L. Wiltshire,Timescape cosmology with radiation fluid, Class. Quantum Grav. 30 (2013) 175006, [arXiv:1306.3208]
2013 arXiv
-
[15]
Wiltshire,Average observational quantities in the timescape cosmology, Phys
D.L. Wiltshire,Average observational quantities in the timescape cosmology, Phys. Rev. D 80 (2009) 123512, [arXiv:0909.0749]
2009 arXiv
-
[16]
Eisenstein, H
D.J. Eisenstein, H. Seo, E. Sirko and D. Spergel,Improving Cosmological Distance Measurements by Reconstruction of the Baryon Acoustic Peak, Astrophys. J. 664 (2007) 675, [astro-ph/0604362]
2007 arXiv
-
[17]
Alcock and B
C. Alcock and B. Paczyński,An evolution free test for non-zero cosmological constantNature 281 (1979) 358
1979
-
[18]
W. E. Ballinger, J. A. Peacock and A. F. Heavens,Measuring the cosmological constant with redshift surveys Mon. Not. R. Astr. Soc.282 (1996) 877 [arXiv:astro-ph/9605017]
1996 arXiv
-
[19]
Matsubara and Y
T. Matsubara and Y. Suto,Cosmological redshift distortion of correlation functions as a probe of the density parameter and the cosmological constant Astrophys. J.470 (1996) L1 [arXiv:astro-ph/9604142]
1996 arXiv
-
[20]
Padmanabhan and M
N. Padmanabhan and M. White,Constraining Anisotropic Baryon Oscillations, Phys. Rev. D77 (2008) 123540, [arXiv:0804.0799]
2008 arXiv
-
[21]
X. Xu, A.J. Cuesta, N. Padmanabhan, D.J. Eisenstein and C.K. McBride,MeasuringDA and H atz = 0.35 from the SDSS DR7 LRGs using baryon acoustic oscillations, Mon. Not. R. Astr. Soc. 431 (2013) 2834, [arXiv:1206.6732]
2013 arXiv
-
[22]
Anderson, E
L. Anderson, E. Aubourg, et al.,The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples, Mon. Not. R. Astr. Soc.441 (2014) 24, [arXiv:1312.4877]
2014 arXiv
-
[23]
Cuesta, M
A.J. Cuesta, M. Vargas-Magaña, et al.,The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the correlation function of LOWZ and CMASS galaxies in Data Release 12, Mon. Not. R. Astr. Soc.457 (2016) 1770, [arXiv:1509.06371]
2016 arXiv
-
[24]
M. Vargas-Magaña, et al.,The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: theoretical systematics and Baryon Acoustic Oscillations in the galaxy correlation function Mon. Not. R. Astr. Soc.477 (2018) 1153 [arXiv:1610.03506]
2018 arXiv
-
[25]
Carter et al., Preprint,The Impact of the Fiducial Cosmology Assumption on BAO Cosmological Parameter Inference[arXiv:1906.03035]
P. Carter et al., Preprint,The Impact of the Fiducial Cosmology Assumption on BAO Cosmological Parameter Inference[arXiv:1906.03035]
1906 arXiv
-
[26]
Heinesen, C
A. Heinesen, C. Blake, Y. Li and D.L. Wiltshire,Baryon acoustic oscillation methods for generic curvature: application to the SDSS-III Baryon Oscillation Spectroscopic Survey J. Cosmol. Astropart. Phys.03 (2019) 003 [arXiv:1811.11963]
2019 arXiv
-
[27]
Aghanim, et al.,Planck 2018 results
N. Aghanim, et al.,Planck 2018 results. VI. Cosmological parameters, arXiv:1807.06209
2018 arXiv
-
[28]
Buchert,On average properties of inhomogeneous fluids in general relativity
T. Buchert,On average properties of inhomogeneous fluids in general relativity. I: Dust cosmologies, Gen. Relativ. Grav.32 (2000) 105, [gr-qc/9906015]
2000 arXiv
-
[29]
Buchert and S
T. Buchert and S. Räsänen,Backreaction in late-time cosmology, Ann. Rev. Nucl. Part. Sci.62 (2012) 57, [arXiv:1112.5335] – 40 –
2012 arXiv
-
[30]
Wiltshire,Cosmic structure, averaging and dark energy, inCosmology and Gravitation: Proc
D.L. Wiltshire,Cosmic structure, averaging and dark energy, inCosmology and Gravitation: Proc. XVth Brazilian School, eds. M. Novello, and S.E. Perez Bergliaffa, (Cambridge Scientific Publishers, Cambridge, 2014) 203–244, [arXiv:1311.3787]
2014 arXiv
-
[31]
Sanchez, D
E. Sanchez, D. Alonso, F.J. Sanchez, J.G.-Bellido and I. Sevilla,Precise Measurement of the Radial Baryon Acoustic Oscillation Scales in Galaxy Redshift Surveys, Mon. Not. R. Astr. Soc. 434 (2013) 2008, [arXiv:1210.6446]
2013 arXiv
-
[32]
Sanchez, A
E. Sanchez, A. Carnero, et al.,Tracing The Sound Horizon Scale With Photometric Redshift Surveys, Mon. Not. R. Astr. Soc.411 (2011) 277, [arXiv:1006.3226]
2011 arXiv
-
[33]
Smith, R
R.E. Smith, R. Scoccimarro and R.K. Sheth,Motion of the acoustic peak in the correlation function, Phys. Rev. D 77 (2008) 043525, [astro-ph/0703620]
2008 arXiv
-
[34]
Seo, E.R
H.-J. Seo, E.R. Siegel, D.J. Eisenstein and M. White,Non-linear structure formation and the acoustic scale, Astrophys. J. 686 (2008) 13, [arXiv:0805.0117]
2008 arXiv
-
[35]
Roukema, T
B.F. Roukema, T. Buchert, J.J. Ostrowski and M.J. France,Evidence for an environment- dependent shift in the baryon acoustic oscillation peak, Mon. Not. R. Astr. Soc.448 (2015) 1660, [arXiv:1410.1687]
2015 arXiv
-
[36]
Dawson, et al.,The Baryon Oscillation Spectroscopic Survey of SDSS-III, Astron
K.S. Dawson, et al.,The Baryon Oscillation Spectroscopic Survey of SDSS-III, Astron. J. 145 (2013) 10, [arXiv:1208.0022]
2013 arXiv
-
[37]
B. Reid, S. Ho, et al.,SDSS-III Baryon Oscillation Spectroscopic Survey Data Release 12: galaxy target selection and large scale structure catalogues, Mon. Not. R. Astr. Soc.455 (2016) 1553, [arXiv:1509.06529]
2016 arXiv
-
[38]
Landy and A.S
S.D. Landy and A.S. Szalay,Bias and variance of angular correlation functions, Astrophys. J. 412 (1993) 64
1993
-
[39]
Peebles,Statistical Analysis of Catalogs of Extragalactic Objects
P.J.E. Peebles,Statistical Analysis of Catalogs of Extragalactic Objects. I. Theory, Astrophys. J. 185 (1973) 413
1973
-
[40]
Bolejko,Relativistic numerical cosmology with silent universes Class
K. Bolejko,Relativistic numerical cosmology with silent universes Class. Quantum Grav.35 (2018) 024003 [arXiv:1708.09143] – 41 –
2018 arXiv
Reviewed August 14, 2026 · model on record in the stance chip above.
Discussion (0). Continue with ORCID to comment.