Generalized Fefferman-space reconstruction conjecture

Let (M~,c~,K~)(\widetilde{\mathcal{M}},\widetilde{\mathbf{c}},\widetilde{K}) be an optical geometry of dimension 2m+2>42m+2>4 with twisting non-shearing congruence of null geodesics K~\widetilde{\mathcal{K}}. Suppose the Weyl tensor satisfies

W~abcdk~av~bk~c=0,W~abcdk~av~b~ck~d=0\widetilde{\mathsf{W}}_{a b c d} \widetilde{k}^{a} \widetilde{v}^{b} \widetilde{k}^{c}=0,\qquad \widetilde{\mathsf{W}}_{a b c d} \widetilde{k}^{a} \widetilde{v}^{b} \widetilde{\nabla}^{c} \widetilde{k}^{d}=0

for any k~Γ(K~)\widetilde{k}\in\Gamma(\widetilde{K}) and v~Γ(K~)\widetilde{v}\in\Gamma(\widetilde{K}^{\perp}), and suppose the Fefferman--Graham obstruction tensor satisfies

F ⁣G~abk~ak~b=0\widetilde{\mathsf{F}\mkern-4mu\mathsf{G}}_{ab}\widetilde{k}^{a}\widetilde{k}^{b}=0

for any k~Γ(K~)\widetilde{k}\in\Gamma(\widetilde{K}). Generalized Fefferman-space reconstruction conjecture. Then (M~,c~,K~)(\widetilde{\mathcal{M}},\widetilde{\mathbf{c}},\widetilde{K}) is locally conformally isometric to a perturbed Fefferman space (M~,c~ξ~,k~)(M,H,J)(\widetilde{\mathcal{M}}',\widetilde{\mathbf{c}}'_{\widetilde{\xi}},\widetilde{k}')\longrightarrow(\mathcal{M},H,J), and the perturbation one-form ξ~\widetilde{\xi} is determined by the CR data (ξα(0),[,ξ0(0)],ξ0(2k))k=1,,m+1\left(\bm{\xi}_{\alpha}^{(0)},[\nabla,\bm{\xi}_{0}^{(0)}],\bm{\xi}_{0}^{(2k)}\right)_{k=1,\ldots,m+1}, where

ξ0(0)=im(αξ(0)ααξα(0)).\bm{\xi}_{0}^{(0)}=\frac{\mathrm{i}}{m}\left(\nabla_{\alpha}\bm{\xi}^{\alpha}_{(0)}-\nabla^{\alpha}\bm{\xi}_{\alpha}^{(0)}\right).

This is proposed as a higher-dimensional generalization of a four-dimensional integration result for perturbed Fefferman spaces. The source does not provide evidence that the conjecture has been proved or disproved.

Sources & referencesView supporting material

Primary source

Arman Taghavi-Chabert, “Perturbations of Fefferman spaces over almost CR manifolds”, arXiv:2309.16986 (2025).

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