Large ensemble decoupling for the paraboloid

Let RR be a large parameter, let BRB_R be a ball or cube of radius or side length RR in R3{\mathbb R}^3, and let ESFE_SF denote the Fourier extension operator associated to the two-dimensional paraboloid, restricted to S[0,1]2S\subset[0,1]^2. A large ensemble is a disjoint union of 1/R1/\sqrt{R}-squares from the partition QR{\mathcal Q}_R of [0,1]2[0,1]^2. Let N=O(R)N=O(R), and let S1,,SNS_1,\ldots,S_N be a partition of [0,1]2[0,1]^2 into large ensembles. Large ensemble decoupling for the paraboloid. For 2p32\le p\le3, one has

EFLp(BR)ϵRϵ(i=1NESiFLp(BR)2)1/2.\|EF\|_{L^p(B_R)}\lesssim_{\epsilon}R^{\epsilon}\left(\sum_{i=1}^N\|E_{S_i}F\|_{L^p(B_R)}^2\right)^{1/2}.

This would extend canonical l2l^2 decoupling from canonical caps to arbitrary unions of such caps, including thin rectangles and disconnected sets. The source provides no resolution status for this conjecture.

Sources & referencesView supporting material

Primary source

Ciprian Demeter, “Beyond canonical decoupling”, arXiv:2402.04989 (2024).

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