English

Approximation of non-archimedean Lyapunov exponents and applications over global fields

Dynamical Systems 2018-03-28 v2 Number Theory

Abstract

Let KK be an algebraically closed field of characteristic 0 that is complete with respect to a non-archimedean absolute value. We establish a locally uniform approximation formula of the Lyapunov exponent of a rational map ff of P1\mathbb{P}^1 of degree d>1d>1 over KK, in terms of the multipliers of nn-periodic points of ff, with an explicit control in terms of nn, ff and KK. As an immediate consequence, we obtain an estimate for the blow-up of the Lyapunov exponent near a pole in one-dimensional families of rational maps over KK. Combined with our former archimedean version, this non-archimedean quantitative approximation allows us to show: - a quantified version of Silverman's and Ingram's recent comparison between the critical height and any ample height on the moduli space Md(Qˉ)\mathcal{M}_d(\bar{\mathbb{Q}}), - two improvements of McMullen's finiteness of the multiplier maps: reduction to multipliers of cycles of exact given period and an effective bound from below on the period, - a characterization of non-affine isotrivial rational maps defined over the function field C(X)\mathbb{C}(X) of a normal projective variety XX in terms of the growth of the degree of the multipliers.

Keywords

Cite

@article{arxiv.1803.06859,
  title  = {Approximation of non-archimedean Lyapunov exponents and applications over global fields},
  author = {Thomas Gauthier and Yusuke Okuyama and Gabriel Vigny},
  journal= {arXiv preprint arXiv:1803.06859},
  year   = {2018}
}

Comments

Some typos fixed