Lorentz-boosted diffusion: initial value formulation and exact solutions

Fuente: arXiv
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Auteur principal: Gavassino, Lorenzo
Format: Preprint
Publié: 2026
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author Gavassino, Lorenzo
author_facet Gavassino, Lorenzo
contents It is well known that the diffusion equation, when treated as a stand-alone partial differential equation, exhibits exponential instabilities in boosted frames, which render the corresponding initial-value problem ill-posed. Recently, however, it was shown that Fick-type diffusion arises as the exact hydrodynamic sector of relativistic Fokker-Planck kinetic theory. In this work, we exploit this kinetic embedding to formulate a modified initial-value problem for one-dimensional Lorentz-boosted diffusion. We show that the resulting dynamics are well posed both forward and backward in time, provided the boosted density profiles admit a kinetic-theory realization. Such profiles form a space of band-limited functions, within which the evolution can be expressed as a discrete superposition of spatially sampled initial data, weighted by a Shannon-Whittaker-type Green function defined on the full Minkowski plane. The Green function is obtained in closed analytic form.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21254
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Lorentz-boosted diffusion: initial value formulation and exact solutions
Gavassino, Lorenzo
Mathematical Physics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
Nuclear Theory
It is well known that the diffusion equation, when treated as a stand-alone partial differential equation, exhibits exponential instabilities in boosted frames, which render the corresponding initial-value problem ill-posed. Recently, however, it was shown that Fick-type diffusion arises as the exact hydrodynamic sector of relativistic Fokker-Planck kinetic theory. In this work, we exploit this kinetic embedding to formulate a modified initial-value problem for one-dimensional Lorentz-boosted diffusion. We show that the resulting dynamics are well posed both forward and backward in time, provided the boosted density profiles admit a kinetic-theory realization. Such profiles form a space of band-limited functions, within which the evolution can be expressed as a discrete superposition of spatially sampled initial data, weighted by a Shannon-Whittaker-type Green function defined on the full Minkowski plane. The Green function is obtained in closed analytic form.
title Lorentz-boosted diffusion: initial value formulation and exact solutions
topic Mathematical Physics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
Nuclear Theory
url https://arxiv.org/abs/2602.21254