Microscopic study of non-Gaussian particle number fluctuations near the critical point

¹ Physics Department, University of Houston, Houston, TX 77204, USA
² Bogolyubov Institute for Theoretical Physics, Kyiv 03680, Ukraine
³ Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

Published online: 17 April 2026

Abstract

We simulate a classical Lennard-Jones fluid at fixed number of particles N = 400 via molecular dynamics to study higher-order particle number cumulants near the liquid-gas critical point, along T = 1.06 T_c, at densities 0.32n_c,0.95n_c, and 1.9n_c. Coordinate space results obtained with a statistics of 2 millions events reveals strong non-Gaussian signals near critical point despite of the suppression due to the baryon number conservation. In momentum space, the cumulants follow ideal gas behavior. Due to collective flow effects imposed the critical signals are partially restored and are especially strong around √s_NN ≈ 7.7 GeV. Our findings are discussed in a context of heavy-ion collision experiments.