Lebesgue measure of the postcritical set of neutral quadratic polynomials

Willie Rush Lim

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arXiv · 2609.35563

Lebesgue measure of the postcritical set of neutral quadratic polynomials

Willie Rush Lim

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Abstract

We prove that the postcritical set of every quadratic polynomial with a neutral fixed point has zero Lebesgue measure. In particular, no arithmetic condition on the rotation number is required. Our proof uses sector renormalization and the pseudo-Siegel bounds of Dudko-Lyubich to derive uniform distortion estimates for the renormalization change of variables. For sector renormalization towers, we also prove the same zero area statement for the associated postcritical set and the optimal Brjuno criterion for the interior of the associated Mother Hedgehog.

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Willie Rush Lim. 2026-09-28. Lebesgue measure of the postcritical set of neutral quadratic polynomials. https://arxiv.org/abs/2609.35563

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