Height-offset variables and pinning at infinity for gradient Gibbs measures on trees

Fuente: arXiv
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Main Authors: Henning, Florian, Kuelske, Christof
Format: Preprint
Published: 2024
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_version_ 1866909931821596672
author Henning, Florian
Kuelske, Christof
author_facet Henning, Florian
Kuelske, Christof
contents Height-offset variables (HOVs) provide a mechanism, known as "pinning at infinity", to lift gradient Gibbs measures (GGMs) - describing interface increments - to proper Gibbs measures that describe absolute heights. Starting from Sheffield's seminal framework, we study HOVs for nearest-neighbor integer-valued gradient models on regular trees, under broad classes of transfer operators requiring only finite second moments and without assuming convexity. We first establish the existence of HOVs as martingale limits, prove the infinite differentiability of their Lebesgue densities, and demonstrate exponential concentration for the associated pinned Gibbs measures. Next we uncover a fundamental trade-off, as the Gibbs measures arising by "pinning at infinity" paradoxically lose several desirable structural properties. We rigorously show that they lose tree-automorphism invariance, the tree-indexed Markov chain property, and extremality within the class of Gibbs measures. Our analysis relies on martingale theory, novel past- and future-tail decompositions, and infinite product representations for moment generating functions, and it applies to free GGMs, as well as to GGMs of height-period two.
format Preprint
id arxiv_https___arxiv_org_abs_2411_13465
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Height-offset variables and pinning at infinity for gradient Gibbs measures on trees
Henning, Florian
Kuelske, Christof
Probability
Mathematical Physics
60K35, 82B41, 82B26
G.3
Height-offset variables (HOVs) provide a mechanism, known as "pinning at infinity", to lift gradient Gibbs measures (GGMs) - describing interface increments - to proper Gibbs measures that describe absolute heights. Starting from Sheffield's seminal framework, we study HOVs for nearest-neighbor integer-valued gradient models on regular trees, under broad classes of transfer operators requiring only finite second moments and without assuming convexity. We first establish the existence of HOVs as martingale limits, prove the infinite differentiability of their Lebesgue densities, and demonstrate exponential concentration for the associated pinned Gibbs measures. Next we uncover a fundamental trade-off, as the Gibbs measures arising by "pinning at infinity" paradoxically lose several desirable structural properties. We rigorously show that they lose tree-automorphism invariance, the tree-indexed Markov chain property, and extremality within the class of Gibbs measures. Our analysis relies on martingale theory, novel past- and future-tail decompositions, and infinite product representations for moment generating functions, and it applies to free GGMs, as well as to GGMs of height-period two.
title Height-offset variables and pinning at infinity for gradient Gibbs measures on trees
topic Probability
Mathematical Physics
60K35, 82B41, 82B26
G.3
url https://arxiv.org/abs/2411.13465