Accelerator modes and their effect in the diffusion properties in the kicked rotator

TL;DR

This paper investigates how accelerator modes influence anomalous diffusion in the standard map, revealing super-diffusive behavior and non-Gaussian distributions through analysis of diffusion exponents and Levy stable distributions.

Contribution

It provides new insights into the role of accelerator modes in causing anomalous diffusion and characterizes the global behavior using diffusion exponents and Levy distributions.

Findings

Accelerator modes induce super-diffusive, ballistic transport.

Presence of non-Gaussian, Levy stable distributions in momentum.

Diffusion properties vary with the kick parameter K.

Abstract

We highlight a few recent results on the effect of the diffusion process in deterministic area preserving maps with noncompact phase space, namely the standard map. In more detail, we focus on the anomalous diffusion arising due to the accelerator modes, i.e. resonant-like features of the phase space which are transported in a super-diffusive (ballistic) manner. Their presence affects also the trajectories lying in the immediate neighborhood resulting in anomalous (non-Gaussian) diffusion. We aim to shed some light on these special properties of the phase space by utilizing the diffusion exponent (rate of diffusion) and the momentum distribution in terms of the L\'evy stable distributions, with the goal to reach an understanding of the global behaviour. To this end we consider a rather large interval for the kick parameter ($0\le K \le 70$) of the standard map where accelerator modes of different periodicity exist.