Nonergodicity and central-limit behavior for long-range Hamiltonians

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Published 21 September 2007 Europhysics Letters Association
, , Citation A. Pluchino et al 2007 EPL 80 26002 DOI 10.1209/0295-5075/80/26002

0295-5075/80/2/26002

Abstract

We present a molecular dynamics test of the Central-Limit Theorem (CLT) in a paradigmatic long-range-interacting many-body classical Hamiltonian system, the HMF model. We calculate sums of velocities at equidistant times along deterministic trajectories for different sizes and energy densities. We show that, when the system is in a chaotic regime (specifically, at thermal equilibrium), ergodicity is essentially verified, and the Pdfs of the sums appear to be Gaussians, consistently with the standard CLT. When the system is, instead, only weakly chaotic (specifically, along longstanding metastable Quasi-Stationary States), nonergodicity (i.e., discrepant ensemble and time averages) is observed, and robust q-Gaussian attractors emerge, consistently with recently proved generalizations of the CLT.

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10.1209/0295-5075/80/26002