Superstatistics from a different perspective

In this paper we elaborate on the recently proposed superstatistics formalism [C. Beck and E.G.D. Cohen, Physica A 322, 267 (2003)], used to interpret unconventional statistics. Their interpretation is that unconventional statistics in dynamical systems arise as weighted averages of the ordinary statistics obeyed by these systems over a statistical distribution of background configurations due to fluctuations intrinsic to the background. In this paper we suggest that the same picture can arise because of the intrinsic dynamics of the system. The dynamics of the system and the background, hence, concur together to determine the overall final statistics: differently evolving systems embedded within the same background can yield different statistical distributions. Some simple examples are provided; among them a toy model able to yield a power-law distribution. Also, some recent independent results are quoted, that appear to support this viewpoint.Comment: 10 pages. Final version to appear in Physica

Further study of the Over-Barrier Model to compute charge exchange processes

In this paper we study theoretically the process of electron capture between one-optical-electron atoms (e.g. hydrogenlike or alkali atoms) and ions at low-to-medium impact velocities ($v/v_e \approx 1$) working on a modification of an already developed classical In this work we present an improvement over the Over Barrier Model (OBM) described in a recent paper [F. Sattin, Phys. Rev. A {\bf 62}, 042711 (2000)]. We show that: i) one of the two free parameters there introduced actually comes out consistently from the starting assumptions underlying the model; ii) the modified model thus obtained is as much accurate as the former one. Furthermore, we show that OBMs are able to accurately predict some recent results of state selective electron capture, at odds with what previously supposed.Comment: RevTeX, 7 pages, 4 eps figures. To appear in Physical Review A (2001-september issue

Chaos in coplanar classical collisions with particles interacting through 1/r21/r^2 forces

The scattering among three particles interacting through $1/r^2$ forces, with opposite charges and widely different masses, is studied in a coplanar geometry. The present work shows that at low impact velocities the output of the collision presents typical fingerprints of chaos. The details of the process are investigated.Comment: ReVTeX (uses epsf), 8 pages, 5 figs. To be published as a Brief Report in Phys. Rev.