Stability criteria of the Vlasov equation and quasi-stationary states of the HMF model

By Yoshiyuki Y. Yamaguchi, J. Barré, Freddy Bouchet, T. Dauxois, Stefano Ruffo. 2003

211 citations recorded by the source corpus.

We perform a detailed study of the relaxation towards equilibrium in the Hamiltonian Mean-Field model, a prototype for long-range interactions in N-particle dynamics. In particular, we point out the role played by the infinity of stationary states of the associated N→∞ Vlasov dynamics. In this context, we derive a new general criterion for the stability of any spatially homogeneous distribution, and compare its analytical predictions with numerical simulations of the Hamiltonian, finite N, dynamics. We then propose, and verify numerically, a scenario for the relaxation process, relying on the Vlasov equation. When starting from a nonstationary or a Vlasov unstable stationary state, the system shows initially a rapid convergence towards a stable stationary state of the Vlasov equation via nonstationary states: we characterize numerically this dynamical instability in the finite N system by introducing appropriate indicators. This first step of the evolution towards Boltzmann–Gibbs equilibrium is followed by a slow quasi-stationary process, that proceeds through different stable stationary states of the Vlasov equation. If the finite N system is initialized in a Vlasov stable homogeneous state, it remains trapped in a quasi-stationary state for times that increase with the nontrivial power law N1.7. Single particle momentum distributions in such a quasi-stationary regime do not have power-law tails, and hence cannot be fitted by the q-exponential distributions derived from Tsallis statistics.

Subfields: Economics and Econometrics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/bf5990127b30ff743369dba2008d7cfd993c5288

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Citations in the corpus

Nonequilibrium statistical mechanics of systems with long-range interactions (2013, background): “7 is the same as the value found in other studies of the HMF model [98].”
Thermodynamics and dynamics of systems with long-range interactions (2010, background): “below, generic initial conditions converge towards a stable stationary state of the Vlasov equation on a timescale of order one, and then stay trapped close to this state fortimes algebraic in N (see [28] foranumerical observation and [60] for a mathematical investigation of the phenomenon). As canb”