Expansion into the vacuum of stochastic gases with long-range interactions.

Krapivsky, P L; Mallick, Kirone · Phys Rev E · 2025

basic_science · Level V

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Abstract

We study the evolution of a system of many point particles initially concentrated in a small region in d dimensions. Particles undergo overdamped motion caused by pairwise interactions through the long-ranged repulsive r^{-s} potential; each particle is also subject to white Gaussian noise. When s<d, the expansion is governed by nonlocal hydrodynamic equations. In the one-dimensional case, we deduce self-similar solutions for all s∈(-2,1). The expansion of Coulomb gases remains well-defined in the infinite-particle limit: The density is spatially uniform and inversely proportional to time, independent of the spatial dimension.