English

Uniform a priori bounds for neutral renormalization

Dynamical Systems 2024-12-31 v2

Abstract

We prove uniform ``pseudo-Siegel'' a priori bounds for Siegel disks of bounded type that give a uniform control of oscillations of their boundaries in all scales. As a consequence, we construct the Mother Hedgehog controlling the postcritical set for any quadratic polynomial with a neutral periodic point and show that this hedgehog has a star-like structure. Pseudo-Siegel bounds imply uniform a priori bounds of the Sector Renormalization, which gives an opportunity to extend Siegel/Pacman Renormalization Theory and Near-Parabolic Renormalization Theory to all near-neutral quadratic polynomials. Various applications beyond quadratic polynomials are also underway.

Keywords

Cite

@article{arxiv.2210.09280,
  title  = {Uniform a priori bounds for neutral renormalization},
  author = {Dzmitry Dudko and Mikhail Lyubich},
  journal= {arXiv preprint arXiv:2210.09280},
  year   = {2024}
}

Comments

v2 adds references to further developments

R2 v1 2026-06-28T03:50:38.643Z