Strong Disorder for Stochastic Heat Flow and 2D Directed Polymers

Fuente: arXiv
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Auteurs principaux: Berger, Quentin, Caravenna, Francesco, Turchi, Nicola
Format: Preprint
Publié: 2025
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author Berger, Quentin
Caravenna, Francesco
Turchi, Nicola
author_facet Berger, Quentin
Caravenna, Francesco
Turchi, Nicola
contents The critical 2D Stochastic Heat Flow (SHF) is a universal measure-valued process that provides a notion of solution to the ill-defined 2D stochastic heat equation. We investigate the SHF in the large-time and strong-disorder regimes, proving a sharp form of local extinction: we identify the rate at which the distribution collapses to zero. We also identify the spatial scale governing the transition from vanishing mass to diverging mass, and from extinction to an averaged behavior. Corresponding results are established for the partition functions of 2D directed polymers, yielding precise free-energy estimates. Our proof provides a unified framework of change of measure and coarse-graining arguments. These results offer new insights into the 2D stochastic heat equation regularized via space-time discretization: for any regime of supercritical disorder strength $β$, including the case where $β> 0$ is kept fixed, the solution exhibits fluctuations on a superdiffusive scale.
format Preprint
id arxiv_https___arxiv_org_abs_2508_02478
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strong Disorder for Stochastic Heat Flow and 2D Directed Polymers
Berger, Quentin
Caravenna, Francesco
Turchi, Nicola
Probability
Primary: 82B44, Secondary: 60K35, 82D60
The critical 2D Stochastic Heat Flow (SHF) is a universal measure-valued process that provides a notion of solution to the ill-defined 2D stochastic heat equation. We investigate the SHF in the large-time and strong-disorder regimes, proving a sharp form of local extinction: we identify the rate at which the distribution collapses to zero. We also identify the spatial scale governing the transition from vanishing mass to diverging mass, and from extinction to an averaged behavior. Corresponding results are established for the partition functions of 2D directed polymers, yielding precise free-energy estimates. Our proof provides a unified framework of change of measure and coarse-graining arguments. These results offer new insights into the 2D stochastic heat equation regularized via space-time discretization: for any regime of supercritical disorder strength $β$, including the case where $β> 0$ is kept fixed, the solution exhibits fluctuations on a superdiffusive scale.
title Strong Disorder for Stochastic Heat Flow and 2D Directed Polymers
topic Probability
Primary: 82B44, Secondary: 60K35, 82D60
url https://arxiv.org/abs/2508.02478