Quantitative Rigidity of pseudo-rotations on the two-torus and Sarnak's conjecture
Abstract
We establish quantitative rigidity results for pseudo-rotations of the two-torus under a (C,δ)-deviation condition relative to their rotation vectors. The main ingredient is a quantitative free-disk estimate that converts bounds on orbit deviation into explicit control of the distance between the iterates and the identity map. Under such a (C,δ)-deviation condition, we show that Hölder continuous super-Liouvillean irrational pseudo-rotations are C0-rigid with an exponential decay rate and that Ck semi-irrational pseudo-rotations of strong non-Brjuno type exhibit Ck−1-rigidity with a superpolynomial decay rate. Moreover, under this deviation condition and sufficiently large irrationality measure, we show that Hölder continuous skew products on 𝕋2 over circle rotations are C0-rigid with a polynomial decay rate. As a consequence, all these classes satisfy Sarnak's conjecture.
Related
BibTeX
@misc{chang2026quantitative,
title = {{Quantitative Rigidity of pseudo-rotations on the two-torus and Sarnak's conjecture}},
author = {Yinshan Chang and Jian Wang and Junchang Zhou},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.26976},
eprint = {2608.26976},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.26976},
}
RIS
TY - UNPB
TI - Quantitative Rigidity of pseudo-rotations on the two-torus and Sarnak's conjecture
AU - Yinshan Chang
AU - Jian Wang
AU - Junchang Zhou
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2608.26976
UR - https://arxiv.org/abs/2608.26976
AB - We establish quantitative rigidity results for pseudo-rotations of the two-torus under a (C,δ)-deviation condition relative to their rotation vectors. The main ingredient is a quantitative free-disk estimate that converts bounds on orbit deviation into explicit control of the distance between the iterates and the identity map. Under such a (C,δ)-deviation condition, we show that Hölder continuous super-Liouvillean irrational pseudo-rotations are C^0-rigid with an exponential decay rate and that C^k semi-irrational pseudo-rotations of strong non-Brjuno type exhibit C^k−1-rigidity with a superpolynomial decay rate. Moreover, under this deviation condition and sufficiently large irrationality measure, we show that Hölder continuous skew products on 𝕋^2 over circle rotations are C^0-rigid with a polynomial decay rate. As a consequence, all these classes satisfy Sarnak's conjecture.
ER -