Ballistic macroscopic fluctuation theory via mapping to point particles

Jitendra Kethepalli; Andrew Urilyon; Tridib Sadhu; Jacopo De Nardis

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arXiv · 2505.18093

Ballistic macroscopic fluctuation theory via mapping to point particles

Jitendra Kethepalli·Andrew Urilyon·Tridib Sadhu·Jacopo De Nardis

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Abstract

Ballistic Macroscopic Fluctuation Theory (BMFT) captures the evolution of fluctuations and correlations in systems where transport is strictly ballistic. We show that, for \emph{generic integrable models}, BMFT can be constructed through a direct mapping onto ensembles of classical or quantum point particles. This mapping generalises the well-known correspondence between hard spheres and point particles: the two-body \emph{scattering shift} now plays the role of an effective rod length for arbitrary interactions. Within this framework, we re-derive both the full-counting statistics and the long-range correlation functions previously obtained by other means, thereby providing a unified derivation. Our results corroborate the general picture that all late-time fluctuations and correlations stem from the initial noise, subsequently convected by Euler-scale hydrodynamics.

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Jitendra Kethepalli, Andrew Urilyon, Tridib Sadhu, Jacopo De Nardis. 2025-05-23. Ballistic macroscopic fluctuation theory via mapping to point particles. https://arxiv.org/abs/2505.18093

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