English

Directional $p$-Adic Littlewood Conjecture for Algebraic Vectors

Dynamical Systems 2025-05-29 v3 Number Theory

Abstract

For every vector α\RRn\overline \alpha\in \RR^n and for every rational approximation (p,q)\RRn×\RR(\overline p,q)\in \RR^n\times\RR we can associate the displacement vector qαpq\alpha-\overline p. We focus on algebraic vectors, namely α=(α1,,αn)\overline \alpha=(\alpha_1,\dots,\alpha_n) such that 1,α1,,αn1, \alpha_1, \dots, \alpha_n span a rank nn number field. For these vectors, we investigate the size of their displacements as well as the distribution of their directions. We give a new proof to the result of Bugeaud in \cite{YannPAdic} saying that algebraic vectors α\overline \alpha satisfy the pp-adic Littlewood Conjecture. Namely, we prove that \begin{equation} \liminf_{k \to \infty} \left( k \abs{k}_p \right)^{1/n} \| k (\alpha_1, \dots, \alpha_n) \|_\infty = 0. \end{equation} Our new proof lets us classify all limiting distributions, with a special weighting, of the sequence of directions of the defects in the ε\varepsilon-approximations of (α1,,αn)(\alpha_1, \dots, \alpha_n). Each such limiting measure is expressed as the pushforward of an algebraic measure on XnX_n to the sphere.

Keywords

Cite

@article{arxiv.2501.04430,
  title  = {Directional $p$-Adic Littlewood Conjecture for Algebraic Vectors},
  author = {Yuval Yifrach},
  journal= {arXiv preprint arXiv:2501.04430},
  year   = {2025}
}
R2 v1 2026-06-28T20:59:44.272Z