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When Normality Tests Detect Equilibrium Distributions of Finite N-Body Systems

Statistical Mechanics 2026-01-30 v4

Abstract

The particle number NN can be used as a quantitative gauge of non-Gaussianity. This idea extends to systems that are not literally finite by assigning them a notional NN that captures the same deviation. For an ideal gas with NN insufficiently large for the thermodynamic limit, the velocity distribution that maximises Havrda-Charv\'at entropy departs markedly from the Maxwell--Boltzmann (Gaussian) form obtained in that limit. We explore how five standard normality tests -- Kolmogorov-Smirnov, Anderson-Darling, Cram\'er--von Mises, Jarque-Bera and Shapiro-Wilk -- respond to samples drawn from this finite-NN equilibrium distribution. A large-scale Monte Carlo study maps the tests' statistical power across system size NN and sample size nn, providing practical reference tables and a heuristic scaling law, visualised as a contour plot, that together indicate when finite-size effects remain detectable.

Keywords

Cite

@article{arxiv.2510.26821,
  title  = {When Normality Tests Detect Equilibrium Distributions of Finite N-Body Systems},
  author = {Jae Wan Shim},
  journal= {arXiv preprint arXiv:2510.26821},
  year   = {2026}
}