Long-range interactions are those where the two-body potential decays algebraically at large distances with a power smaller than the spatial dimension. Examples include self gravitating systems, dipolar magnets and others. These systems are non-additive, and as a result they exhibit some unusual properties such as negative specific heat, inequivalence of statistical ensembles and slow relaxation processes where the relaxation time diverges with the system size.
Such slow relaxation leads in some cases to non-Boltzmann states (termed quasistationary states) which are stationary in the thermodynamic limit.
Dynamical and thermodynamical properties resulting from long-range interactions are being explored in our group.