Stein's conjecture for weighted extension operators

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Let Σ⊂Rd\Sigma\subset\mathbb{R}^d be a C2C^2 hypersurface with surface measure dσ\mathrm{d}\sigma, let f∈L2(Σ;dσ)f\in L^2(\Sigma;\mathrm{d}\sigma), and let ww be a nonnegative weight. Let N(σ)N(\sigma) denote the normal to Σ\Sigma at σ\sigma, and let XwXw be the X-Ray transform of ww. Stein's conjecture. Under the hypotheses of the Mizohata–Takeuchi conjecture, one has

∫Rd∣Ef∣2w dx≲∫Σ∣f(σ)∣2sup⁡ℓ∥N(σ)Xw(ℓ) dσ(σ).\int_{\mathbb{R}^d}|\mathcal E f|^2w\,\mathrm{d}x\lesssim\int_\Sigma |f(\sigma)|^2\sup_{\ell\parallel N(\sigma)}Xw(\ell)\,\mathrm{d}\sigma(\sigma).

The supplied text presents this as a conjecture arising from the connection between Kakeya or Nikodym maximal functions and Bochner–Riesz multipliers; it gives no resolution status.

References

Primary source

Hannah Cairo, “A Counterexample to the Mizohata-Takeuchi Conjecture”, arXiv:2502.06137 (2025).

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