Pith. sign in

REVIEW 3 major objections 4 minor 3 cited by

A first-order geometric Lagrangian can generate the standard constraints of four-dimensional conformal gravity dynamically, reducing on-shell to the usual Weyl-squared action.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · deepseek-v4-flash

2026-08-03 02:43 UTC pith:5AP7KKZF

load-bearing objection A plausible first-order reformulation of D=4 conformal gravity, but the reduction to Weyl-squared rests on a cancellation that is asserted, not shown. the 3 major comments →

arxiv 2602.09664 v2 pith:5AP7KKZF submitted 2026-02-10 hep-th gr-qc

Dynamical Implementation of the Constraints in Conformal Gravity

classification hep-th gr-qc
keywords conformal gravityCartan geometryfirst-order Lagrangianconformal torsionWeyl tensorgauge theory of gravityauxiliary fieldsMacDowell–Mansouri
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper tries to establish that the constraints on the fields of four-dimensional conformal gravity — usually imposed by hand as kinematic conditions — can instead be obtained dynamically from a first-order Lagrangian written in Cartan form. The construction works like the Cartan–Einstein formulation of relativity: variations with respect to the auxiliary fields and gauge fields enforce the constraints, with vanishing conformal torsion imposed by a Lagrange multiplier and additionally justified by a symmetry argument. With the constraints in place and the coefficients fixed by conformal invariance, the Lagrangian reduces to the standard conformal gravity action quadratic in the Weyl tensor. A sympathetic reader would care because this gives conformal gravity a cleaner gauge-theoretic status and a template for harder cases in six dimensions and in superconformal theories. The paper is explicit that one extra sector does not vanish at first order; it argues that this sector decouples from the standard fields at zero conformal torsion and can be truncated.

Core claim

The central claim is that in D=4 there exists a first-order geometric Lagrangian for conformal gravity, built from the vielbein and the conformal gauge fields, whose field equations implement the standard constraints: the auxiliary fields are set equal to the corresponding curvatures, the conformal torsion is forced to vanish by a Lagrange multiplier, and the equation of motion for the special-conformal field yields the standard identification of the symmetric part of S with the Schouten tensor. Imposing these dynamical constraints, together with conformal invariance of the off-shell Lagrangian, fixes the coefficients and reduces the action to the standard conformal gravity expression, quadr

What carries the argument

The load-bearing object is the Cartan connection of the conformal group SO(2,4) with gauge subgroup HC=(SO(1,3)×SO(1,1))⋉R^{1,3}; its curvature splits into the Weyl 2-form W^ab, dilatation curvature G, special-conformal curvature C^a, and conformal torsion T^a. The proposed first-order Lagrangian is the most general Lorentz- and scale-invariant 4-form built from these curvatures, auxiliary 0-form fields, and a Lagrange multiplier that enforces T^a=0. Varying the auxiliary fields identifies them with curvatures; varying the multiplier enforces zero conformal torsion; varying S^a, b and the spin connection produces the standard constraints and expresses the multiplier on shell. Conformal invar

Load-bearing premise

The load-bearing premise is that the extra first-order sector built from S_[ab], G_ab, R_[ab] and C^a_{ab} decouples from the standard fields at T^a=0 and can be truncated; the paper states that it cannot make these quantities vanish at first order.

What would settle it

Take a solution with T^a=0 but nonzero G_ab or S_[ab] and compute the full second-order action without truncation; if the equations of motion for b_a and S_[ab] admit propagating solutions on a Ricci-flat background, or if b_a develops a ghost kinetic term, the claimed reduction to pure Weyl gravity fails. More directly, check whether the variation of the untruncated action with respect to b_a forces b_a=0 at T^a=0; if it does not, the extra sector cannot be dropped.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • The kinematical constraints of conformal gravity are turned into dynamical consequences: they follow from the field equations of a single first-order action, just as the torsion constraint follows in the Cartan–Einstein theory.
  • At T^a=0, the second-order Lagrangian loses the S_[ab], b_a and G_ab sector entirely, leaving the standard Weyl-squared action, so Weyl invariance at second order is a global symmetry.
  • The Lagrange multiplier term, with its on-shell expression in terms of C^a, shows that vanishing conformal torsion is compatible with, and required by, the Yang–Mills-type gauge invariance under HC.
  • The construction is intended as the prototype for D=6 conformal gravity and for superconformal extensions, where the algebraic structure is richer.
  • Because the Lagrangian is written in first-order geometric form without Hodge duals or a chosen metric, it provides a frame-independent action principle for conformal gravity.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the decoupling of the extra sector is made fully rigorous, the same mechanism should convert the kinematical constraints of D=6 conformal gravity into field equations; the obstruction to doing so is likely group-theoretic rather than technical.
  • The Yang–Mills-invariance argument for T^a=0 suggests a test theory in which that invariance is dropped while the Cartan bundle is kept, yielding a conformal gravity with nonvanishing conformal torsion and a different particle content.
  • The truncation could be probed by computing the Hamiltonian of the full first-order theory before dropping S_[ab] and G_ab; if those fields carry negative-norm states, the truncation is not merely aesthetic but required for unitarity.
  • The MacDowell–Mansouri form hints that the first-order action may admit a topological interpretation, with the Weyl term emerging from boundary dynamics; examining the boundary terms in the second-order reduction would make that explicit.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. The paper constructs a first-order, Cartan-geometric Lagrangian for four-dimensional conformal gravity. The Lagrangian is built from the conformal curvatures W^{ab}, C^a, G, T^a, auxiliary zero-forms, and a Lagrange multiplier that imposes vanishing conformal torsion. Variation with respect to the auxiliary fields identifies them with the curvatures; the gauge-field equations are claimed to produce the standard constraints on the Weyl tensor and to determine the Lagrange multiplier. Conformal-boost invariance and a Yang-Mills-like HC-invariance then fix the Lagrangian coefficients up to overall normalization. At T^a=0, after substituting the contorsion and eliminating S_{(ab)}, the authors claim the Lagrangian reduces to the standard Weyl-squared action, Eq. (5.5).

Significance. If the reduction to the Weyl Lagrangian is correct, the paper gives a useful first-order Cartan formulation of conformal gravity and a symmetry-based rationale for the conformal-torsion constraint. The explicit variation calculations in Section 3, the coefficient conditions (3.41), and the MacDowell-Mansouri structure (5.2) are genuine strengths. The paper also connects to a substantial literature and identifies clear follow-up directions in higher dimensions and superconformal theories. However, the central claim is currently supported only partly: the torsion constraint is inserted by hand, and the decisive cancellation that eliminates the S_[ab]/b_a sector is asserted rather than demonstrated. The result is plausible and likely repairable, but the missing derivation blocks acceptance in the present form.

major comments (3)
  1. [Section 5, Eqs. (5.3)-(5.5)] The reduction to the Weyl Lagrangian rests on the assertion, after Eq. (5.3) and again after (5.4), that at T^a=0 'all the contributions in S_[ab] and b_a exactly cancel out' and that varying with respect to S_(ab) yields (5.5). The intermediate algebra is not shown. This is load-bearing: (5.4) explicitly contains the kinetic term 8 D^L_[a b_b] D^{L a} b^b and the linear coupling 8 S_[ab](R^{[ab]} - 2 D^L_[a b_b]). Unless the cancellation is exhibited, the theory may retain propagating, ghost-like b_a degrees of freedom and (5.5) is not established. Please provide the detailed computation, including the on-shell expression for S_(ab) before substitution and the cancellation of all b-dependent terms, or cite a prior derivation that does this step. The same missing step underlies the 'decoupling/truncation' of S_[ab], G_ab, R_[ab], and C^a_ab in Section 3.3.
  2. [Abstract and Section 3, Eq. (3.3)] The claim that the standard constraints 'emerge dynamically' is stronger than what the paper actually shows. Vanishing conformal torsion is not derived from a field equation; it is imposed by the Lagrange multiplier term V^a D Phi_a in Eq. (3.1), giving Eq. (3.3). Moreover, Section 3.3 explicitly states that W^a_[b|c]a=0, S_[ab]=0, G_ab=0 and C^a_ab=0 are not obtained at first order and are only later asserted to decouple at T^a=0. The abstract and Section 1 should be qualified so that the reader can distinguish constraints obtained by variation (e.g. the Schouten-type relations) from constraints imposed by the Lagrange multiplier and from fields that are subsequently truncated.
  3. [Section 4.1, around Eq. (4.3)] The treatment of the Lagrange multiplier term under special conformal boosts is incomplete. The text states that because delta_k T^a=0, 'the multiplier Phi_a should be invariant' and that this agrees with the on-shell expression (3.44) once (4.4) is used. For an off-shell first-order Lagrangian, Phi_a is an independent field; invariance of the action requires either a transformation rule for Phi_a or a proof that V^a D Phi_a is invariant up to boundary terms. The on-shell check after imposing (4.4) is not sufficient. Moreover, with the final coefficient choice (4.4) one has c1 = -d1, so (3.44) actually gives Phi^a = 0; this should be stated explicitly, since it makes the 'agreement' trivially satisfied.
minor comments (4)
  1. [Notation, Eqs. (3.5), (3.38), (5.4)] The distinction between the Lorentz-covariant derivative D^L and the Lorentz-plus-scale covariant derivative D is not always explicit in equations such as (3.5), (3.38), and (5.4). Please define once and use consistently.
  2. [Eq. (5.5)] The final Lagrangian is written as -R_{abcd}R^{abcd} + 2 R_{ab}R^{ab} - (1/3)R^2. With standard conventions this is the negative of the usual Weyl-squared Lagrangian; please state the signature/normalization convention or adjust the overall sign.
  3. [Section 3.3, Eq. (3.44)] Equation (3.44) is said to follow from (3.37) using (3.41), but the intermediate simplification is not shown. Since (3.44) is later used in the symmetry discussion in Section 4.1, a short derivation would improve transparency.
  4. [Section 4.2, Eq. (4.9)] The statement that the right-hand side of (4.9) 'identically vanishes at T^a=0 by virtue of the torsion Bianchi identity' is terse. A one-line explanation of why the total derivative term vanishes would help the reader.

Circularity Check

0 steps flagged

No significant circularity: the final action is selected from a general first-order ansatz by field equations and conformal invariance, not restated as its own input.

full rationale

The paper's central derivation starts from the explicit general ansatz (3.1) with arbitrary coefficients and auxiliary fields. The target Weyl action is not an input: it emerges only after coefficient relations (3.41) and (4.4) are imposed via field equations and conformal-boost invariance. The only constraint put in by hand is T^a=0, through the Lagrange multiplier term V^a D Phi_a, and the paper says so explicitly: 'to implement the conformal-torsion constraint, our Lagrangian will include a two-form Lagrange multiplier that enforces vanishing of the conformal torsion.' Calling that emergence 'dynamical' is loose but transparent, and it is independently motivated by the H_C Yang-Mills invariance calculation (4.9)-(4.10), so no prediction reduces to a fitted input. The main weakness is the asserted cancellation of S_[ab], G_ab and b_a at T=0 (Section 5: 'all the contributions in S_[ab] and b_a exactly cancel out') and the Section 3.3 truncation of the non-vanishing antisymmetric sector; these are nontrivial algebraic claims whose intermediate steps are not displayed, which is a correctness risk, not a circularity. Self-citations ([27], [49], [50]) appear only as compatibility or interpretive remarks and are not load-bearing; the final form is checked against external references [17,19,21,26,48]. I find no circular step that reduces the claimed result to its own input.

Axiom & Free-Parameter Ledger

1 free parameters · 5 axioms · 2 invented entities

The central construction relies on a Lagrange multiplier that imposes the torsion constraint, on coefficient relations chosen to enforce conformal invariance, and on an asserted decoupling of an extra sector. These are the main costs the reader pays beyond the standard conformal-gravity background.

free parameters (1)
  • Lagrangian coefficients a1,a2,b1,b4,c1,d1 = b4=b1; c1=2a2=-d1; b1-4a1-4a2=2d1; b1 != 4(a1+a2); b1 != 4(a1-a2)
    These relations are imposed by hand to satisfy vacuum equations of motion and special conformal invariance (eqs. 3.41, 4.4). The remaining a2 is the overall normalization of the Weyl-squared term and a1 is a boundary coefficient.
axioms (5)
  • standard math Conformal algebra so(2,4) and its contraction H_C=(SO(1,3)xSO(1,1))⋉R^{1,3}, with curvatures (2.9) and Bianchi identities (2.11)
    Background Cartan/Lie algebra structure used throughout; stated in Section 2 and Appendix A.
  • domain assumption The standard constraints of conformal gravity listed in Appendix B define the target theory
    The paper takes the literature's constraints (W^a_[bcd]=0, W^[ab|cd]=0, W^b_a|cb=0, T^a=0) as the correct target; if those are not the correct constraints, the claimed reduction is not to standard conformal gravity.
  • ad hoc to paper The sector S_[ab], G_ab, R_[ab], C^a_ab decouples from the standard fields at T^a=0 and can be truncated
    Section 3.3: 'this sector gets decoupled ... and can be truncated out from the theory'; no complete proof of consistent truncation is provided.
  • ad hoc to paper The Lagrange multiplier Phi_a is invariant under special conformal boosts
    Section 4.1 says the multiplier 'should be invariant under conformal boosts'; the on-shell expression (3.44) is quoted as justification, not an off-shell proof.
  • domain assumption Weyl symmetry becomes global at second order, so the b_a field can be eliminated/dressed away
    The paper invokes this known mechanism from [17,19,48] to remove b from the second-order action; it is a background result, not proven here.
invented entities (2)
  • Lagrange multiplier 2-form Phi_a no independent evidence
    purpose: Enforce T^a=0 in the Lagrangian (3.1); on-shell it is expressed in terms of C^a (eq. 3.44).
    Not a physical field; introduced as a compromise because vanishing torsion is not derivable from the spin-connection e.o.m. No independent falsifiable prediction is associated with it.
  • Auxiliary 0-forms eW^{abcd}, eT^{abc}, eC^{abc}, eG^{ab} no independent evidence
    purpose: Render the Lagrangian first-order and geometric without using Hodge duals; their variations identify them with curvature components (3.2).
    Algebraic auxiliary fields, solved locally; they introduce no new degrees of freedom and have no independent observable content.

pith-pipeline@v1.3.0-alltime-deepseek · 20711 in / 16666 out tokens · 156539 ms · 2026-08-03T02:43:17.460026+00:00 · methodology

0 comments
read the original abstract

We propose a first-order geometric Lagrangian for four-dimensional conformal gravity within the Cartan formulation, which yields, dynamically, the standard constraints on the fields, expected for conformal gravity. Upon imposing the dynamical constraints, together with the request of conformal invariance of the off-shell Lagrangian, the theory reduces to the standard expression for conformal gravity, in terms of quadratic curvature invariants. Our results clarify the geometric status of conformal gravity as a gauge theory and open the way to a similar dynamical implementation of the constraints in higher dimensions and supersymmetric extensions.

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 3 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Jordan Frame in Supergravity and Cosmology

    hep-th 2026-05 conditional novelty 6.0

    New supergravity ξ-attractors built by choosing the Kähler potential first match exponential and polynomial α-attractors with ξ=1/(6α), and Palatini-style supergravity with scalars is shown inconsistent with superconf...

  2. Jordan Frame in Supergravity and Cosmology

    hep-th 2026-05 unverdicted novelty 6.0

    The paper introduces new exponential and polynomial supergravity ξ-attractor models in the Jordan frame with non-minimal coupling and shows that Palatini gravity with independent affine connection has no supergravity ...

  3. Lecture Notes on Symmetry Reduction via the Dressing Field Method

    hep-th 2026-03 unverdicted novelty 1.0

    Lecture notes on the Dressing Field Method for symmetry reduction, presenting a framework for invariant observables with examples from Chern-Simons theory, electromagnetism, Higgs model, supersymmetry, and general relativity.

Reference graph

Works this paper leans on

60 extracted references · 3 linked inside Pith · cited by 2 Pith papers

  1. [1]

    H. Weyl. Gravitation and electricity.Sitzungsber. Preuss. Akad. Wiss. Berlin (Math. Phys. ), 1918:465, 1918

  2. [2]

    R. Bach. Zur Weylschen Relativit ¨atstheorie und der Weylschen Erweiterung des Kr¨ ummungstensorbegriffs.Math. Z., 9(1):110–135, 1921

  3. [3]

    K. S. Stelle. Classical Gravity with Higher Derivatives.Gen. Rel. Grav., 9:353–371, 1978. 23

  4. [4]

    A. O. Barut and W. E. Brittin, editors.De Sitter and Conformal Groups and their Applications. Proceedings, 13th Summer Institute for Theoretical Physics: Boulder, CO, USA, June 29-July 03, 1970, volume 13 ofLectures in Theoretical Physics, Boulder, 1971. Colorado Associated Univ. Press

  5. [5]

    J. P. Harnad and R. B. Pettitt. Gauge Theories for Space-Time Symmetries.J. Math. Phys., 17:1827–1837, 1976

  6. [6]

    P. D. Mannheim. Making the Case for Conformal Gravity.Found. Phys., 42:388–420, 2012

  7. [7]

    Anastasiou and R

    G. Anastasiou and R. Olea. From conformal to Einstein Gravity.Phys. Rev. D, 94(8):086008, 2016

  8. [8]

    Corral, G

    C. Corral, G. Giribet, and R. Olea. Self-dual gravitational instantons in conformal gravity: Conserved charges and thermodynamics.Phys. Rev. D, 104(6):064026, 2021

  9. [9]

    Anastasiou, I

    G. Anastasiou, I. J. Araya, and R. Olea. Energy functionals from Conformal Gravity.JHEP, 10:123, 2022

  10. [10]

    K. S. Stelle. Renormalization of Higher Derivative Quantum Gravity.Phys. Rev. D, 16:953– 969, 1977

  11. [11]

    Ferrara and B

    S. Ferrara and B. Zumino. Structure of Conformal Supergravity.Nucl. Phys. B, 134:301–326, 1978

  12. [12]

    Ferrara, Marcus T

    S. Ferrara, Marcus T. Grisaru, and P. van Nieuwenhuizen. Poincare and Conformal Super- gravity Models With Closed Algebras.Nucl. Phys. B, 138:430–444, 1978

  13. [13]

    S. C. Lee and P. van Nieuwenhuizen. Counting of states in higher-derivative field theories. Phys. Rev. D, 26:934–937, Aug 1982

  14. [14]

    R. J. Riegert. The particle content of linearized conformal gravity.Physics Letters, 105A(3), 1984

  15. [15]

    Antoniadis and N

    I. Antoniadis and N. C. Tsamis. Weyl invariance and the cosmological constant.SLAC-PUB- 3297, 3 1984

  16. [16]

    Ferrara, M

    S. Ferrara, M. Kaku, P. K. Townsend, and P. van Nieuwenhuizen. Gauging the Graded Conformal Group with Unitary Internal Symmetries.Nucl. Phys. B, 129:125–134, 1977

  17. [17]

    M. Kaku, P. K. Townsend, and P. van Nieuwenhuizen. Gauge Theory of the Conformal and Superconformal Group.Phys. Lett. B, 69:304–308, 1977

  18. [18]

    E. A. Lord and P. Goswami. Gauging the Conformal Group.Pramana, 25:635–640, 1985

  19. [19]

    Butter, S

    D. Butter, S. M. Kuzenko, J. Novak, and S. Theisen. Invariants for minimal conformal supergravity in six dimensions.JHEP, 12:072, 2016. 24

  20. [20]

    R. W. Sharpe.Differential Geometry: Cartan’s Generalization of Klein’s Erlangen Program, volume 166 ofGraduate text in Mathematics. Springer, 1996

  21. [21]

    Attard, J

    J. Attard, J. Franc ¸ois, and S. Lazzarini. Weyl gravity and Cartan geometry.Phys. Rev. D, 93(8):085032, 2016

  22. [22]

    S. W. MacDowell and F. Mansouri. Unified Geometric Theory of Gravity and Supergravity. Phys. Rev. Lett., 38:739, 1977. [Erratum: Phys.Rev.Lett. 38, 1376 (1977)]

  23. [23]

    Maldacena

    J. Maldacena. Einstein Gravity from Conformal Gravity.arXiv:1105.5632 [hep-th], 2011

  24. [24]

    P. D. Mannheim. Alternatives to dark matter and dark energy.Prog. Part. Nucl. Phys., 56:340–445, 2006

  25. [25]

    Korzynski and J

    M. Korzynski and J. Lewandowski. The Normal conformal Cartan connection and the Bach tensor.Class. Quant. Grav., 20:3745–3764, 2003

  26. [26]

    J. T. Wheeler. Weyl gravity as general relativity.Phys. Rev. D, 90(2):025027, 2014

  27. [27]

    D’ Auria and L

    R. D’ Auria and L. Ravera. Conformal gravity with totally antisymmetric torsion.Phys. Rev. D, 104(8):084034, 2021

  28. [28]

    Franc ¸ois and L

    J. Franc ¸ois and L. Ravera. Cartan geometry, supergravity, and group manifold approach. Archivum Math., 60:4, 2024

  29. [29]

    ´E. Cartan. Les r ´ecentes g´en´eralisations de la notion d’espace.Bull. Sci. Math., 48:825–861, 1924

  30. [30]

    ´E. Cartan. Sur les vari´et´es `a connexion projective.Bull. Soc. Math. France, 52:205–241, 1924

  31. [31]

    ´E. Cartan. Les espaces `a connexion conforme.Ann. Polon. Math., 2:171–221, 1923

  32. [32]

    Ne’eman and T

    Y. Ne’eman and T. Regge. Gravity and Supergravity as Gauge Theories on a Group Manifold. Phys. Lett. B, 74:54–56, 1978

  33. [33]

    Ne’eman and T

    Y. Ne’eman and T. Regge. Gauge Theory of Gravity and Supergravity on a Group Manifold. Riv. Nuovo Cim., 1N5:1, 1978

  34. [34]

    Yang and R

    C.-N. Yang and R. L. Mills. Conservation of Isotopic Spin and Isotopic Gauge Invariance. Phys. Rev., 96:191–195, 1954

  35. [35]

    Ehresmann and Collectif

    C. Ehresmann and Collectif. Les connexions infinit´esimales dans un espace fibr´e diff´erentiable. InS ´eminaire Bourbaki : ann ´ees 1948/49 - 1949/50 - 1950/51, expos ´es 1-49, number 1 in S´eminaire Bourbaki, pages 153–168. Soci´et´e math´ematique de France, 1952. talk:24

  36. [36]

    Penrose and M

    R. Penrose and M. A. H. MacCallum. Twistor theory: An approach to the quantisation of fields and space-time.Physics Reports, 6(4):241 – 316, 1973

  37. [37]

    R. Penrose. The Twistor Program.Rept. Math. Phys., 12:65–76, 1977. 25

  38. [38]

    Friedrich

    H. Friedrich. Twistor connection and normal conformal cartan connection.General Relativity and Gravitation, 8(5):303–312, 1977

  39. [39]

    Burdet, C

    G. Burdet, C. Duval, and M. Perrin. Cartan structures on galilean manifolds: The chronopro- jective geometry.Journal of Mathematical Physics, 24(7):1752–1760, 1983

  40. [40]

    C. G. Callan, Jr., S. R. Coleman, and R. Jackiw. A New improved energy-momentum tensor. Annals Phys., 59:42–73, 1970

  41. [41]

    S. R. Coleman and R. Jackiw. Why dilatation generators do not generate dilatations?Annals Phys., 67:552–598, 1971

  42. [42]

    Polchinski

    J. Polchinski. Scale and Conformal Invariance in Quantum Field Theory.Nucl. Phys. B, 303:226–236, 1988

  43. [43]

    Nakayama

    Y. Nakayama. Scale invariance vs conformal invariance.Phys. Rept., 569:1–93, 2015

  44. [44]

    Fioresi and M

    R. Fioresi and M. A. Lled ´o.The Minkowski and Conformal Superspaces: The Classical and Quantum Descriptions. World Scientific, 2015

  45. [45]

    K. Ogiue. Theory of conformal connections.Kodai Math. Sem. Rep., 19:193–224, 1967

  46. [46]

    Kobayashi.Transformation Groups in Differential Geometry

    S. Kobayashi.Transformation Groups in Differential Geometry. Springer, 1972

  47. [47]

    Cap and J

    A. Cap and J. Slovak.Parabolic Geometries I: Background and General Theory, volume 1 of Mathematical Surveys and Monographs. American Mathematical Society, 2009

  48. [48]

    M. Kaku, P. K. Townsend, and P. van Nieuwenhuizen. Properties of Conformal Supergravity. Phys. Rev. D, 17:3179, 1978

  49. [49]

    J. T. Franc ¸ois and L. Ravera. Geometric Relational Framework for General-Relativistic Gauge Field Theories.Fortsch. Phys., 73(1-2):2400149, 2025

  50. [50]

    Franc ¸ois and L

    J. Franc ¸ois and L. Ravera. Reassessing the foundations of metric-affine gravity.Eur. Phys. J. C, 85:902, 2025

  51. [51]

    Anastasiou, I

    G. Anastasiou, I. J. Araya, and R. Olea. Einstein Gravity from Conformal Gravity in 6D. JHEP, 01:134, 2021

  52. [52]

    Boulanger and D

    N. Boulanger and D. Rovere. 8D conformal gravity with Einstein sector, and its relation to the Q-curvature.arXiv:2511.01368 [hep-th], 2025

  53. [53]

    Butter, S

    D. Butter, S. M. Kuzenko, J. Novak, and G. Tartaglino-Mazzucchelli. Conformal supergravity in five dimensions: New approach and applications.JHEP, 02:111, 2015

  54. [54]

    Butter, J

    D. Butter, J. Novak, and G. Tartaglino-Mazzucchelli. The component structure of conformal supergravity invariants in six dimensions.JHEP, 05:133, 2017. 26

  55. [55]

    D’ Auria and P

    R. D’ Auria and P. Fr´e. Geometric Supergravity in d = 11 and Its Hidden Supergroup.Nucl. Phys. B, 201:101–140, 1982. [Erratum: Nucl.Phys.B 206, 496 (1982)]

  56. [56]

    Andrianopoli, R

    L. Andrianopoli, R. D’ Auria, and L. Ravera. Hidden Gauge Structure of Supersymmetric Free Differential Algebras.JHEP, 08:095, 2016

  57. [57]

    Andrianopoli, R

    L. Andrianopoli, R. D’ Auria, and L. Ravera. More on the Hidden Symmetries of 11D Supergravity.Phys. Lett. B, 772:578–585, 2017

  58. [58]

    C. A. Cremonini, P. A. Grassi, R. Noris, and L. Ravera. Supergravities and branes from Hilbert-Poincar´e series.JHEP, 12:088, 2023

  59. [59]

    C. A. Cremonini, P. A. Grassi, R. Noris, L. Ravera, and A. Santi. Fermionic Spencer Co- homologies of D=11 Supergravity.arXiv:2411.16869 [hep-th], accepted for publication in Advances in Theoretical and Mathematical Physics, 2024

  60. [60]

    Imbimbo and L

    C. Imbimbo and L. Porro. One Ring to Rule Them All: A Unified Topological Framework for 4D Superconformal Anomalies.arXiv:2507.16505 [hep-th], 2025. 27