Jointly invariant measures for the Kardar-Parisi-Zhang Equation

Fuente: arXiv
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Main Authors: Groathouse, Sean, Rassoul-Agha, Firas, Seppäläinen, Timo, Sorensen, Evan
Format: Preprint
Published: 2023
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_version_ 1866912479801507840
author Groathouse, Sean
Rassoul-Agha, Firas
Seppäläinen, Timo
Sorensen, Evan
author_facet Groathouse, Sean
Rassoul-Agha, Firas
Seppäläinen, Timo
Sorensen, Evan
contents We give an explicit description of the jointly invariant measures for the KPZ equation. These are couplings of Brownian motions with drift, and can be extended to a process defined for all drift parameters simultaneously. We term this process the KPZ horizon (KPZH). As a corollary of this description, we resolve a recent conjecture of Janjigian, and the second and third authors by showing the existence of a random, countably infinite dense set of directions at which the Busemann process of the KPZ equation is discontinuous. This signals instability and shows the failure of the one force--one solution principle and the existence of at least two extremal semi-infinite polymer measures in the exceptional directions. As the inverse temperature parameter $β$ for the KPZ equation goes to $\infty$, the KPZH converges to the stationary horizon (SH) first introduced by Busani, and studied further by Busani and the third and fourth authors. As $β\searrow 0$, the KPZH converges to a coupling of Brownian motions that differ by linear shifts, which is a jointly invariant measure for the Edwards-Wilkinson fixed point.
format Preprint
id arxiv_https___arxiv_org_abs_2309_17276
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Jointly invariant measures for the Kardar-Parisi-Zhang Equation
Groathouse, Sean
Rassoul-Agha, Firas
Seppäläinen, Timo
Sorensen, Evan
Probability
We give an explicit description of the jointly invariant measures for the KPZ equation. These are couplings of Brownian motions with drift, and can be extended to a process defined for all drift parameters simultaneously. We term this process the KPZ horizon (KPZH). As a corollary of this description, we resolve a recent conjecture of Janjigian, and the second and third authors by showing the existence of a random, countably infinite dense set of directions at which the Busemann process of the KPZ equation is discontinuous. This signals instability and shows the failure of the one force--one solution principle and the existence of at least two extremal semi-infinite polymer measures in the exceptional directions. As the inverse temperature parameter $β$ for the KPZ equation goes to $\infty$, the KPZH converges to the stationary horizon (SH) first introduced by Busani, and studied further by Busani and the third and fourth authors. As $β\searrow 0$, the KPZH converges to a coupling of Brownian motions that differ by linear shifts, which is a jointly invariant measure for the Edwards-Wilkinson fixed point.
title Jointly invariant measures for the Kardar-Parisi-Zhang Equation
topic Probability
url https://arxiv.org/abs/2309.17276