English

Long hitting time, slow decay of correlations and arithmetical properties

Dynamical Systems 2009-07-14 v5 Number Theory

Abstract

Let τr(x,x0)\tau_r(x,x_0) be the time needed for a point xx to enter for the first time in a ball Br(x0)B_r(x_0) centered in x0x_0, with small radius rr. We construct a class of translations on the two torus having particular arithmetic properties (Liouville components with intertwined denominators of convergents) not satisfying a logarithm law, i.e. such that for generic x,x0x,x_0 \liminf_{r\to 0} \frac{\log \tau_r(x,x_0)}{-\log r} = \infty. By considering a suitable reparametrization of the flow generated by a suspension of this translation, using a previous construction by Fayad, we show the existence of a mixing system on three torus having the same properties. The speed of mixing of this example must be subpolynomial, because we also show that: in a system having polynomial decay of correlations the above ratio of logarithms (which is also called the lower hitting time indicator) is bounded (it is a function of the local dimension and the speed of correlation decay). More generally, this shows that reparametrizations of torus translations having a Liouville component cannot be polynomially mixing.

Keywords

Cite

@article{arxiv.0801.3109,
  title  = {Long hitting time, slow decay of correlations and arithmetical properties},
  author = {Stefano Galatolo and Pietro Peterlongo},
  journal= {arXiv preprint arXiv:0801.3109},
  year   = {2009}
}

Comments

19 pages, in the new version some misprint and small errors are corrected