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Main Authors: Beffara, Vincent, Faipeur, Corentin, Oke, Tejas
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.16486
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author Beffara, Vincent
Faipeur, Corentin
Oke, Tejas
author_facet Beffara, Vincent
Faipeur, Corentin
Oke, Tejas
contents We consider the random cluster model with parameter $q<1$, for which the FKG inequalities are not valid. On the square lattice, stochastic comparison with Bernoulli percolation implies that the model is subcritical (respectively supercritical) when $p \leq q/(1+q)$ (resp. $p \geq 1/2$); in this paper, we extend these two regions, by improving the classical stochastic comparisons. Assuming the existence of the critical point, this reduces its possible range. The proof relies on a modification of the usual Glauber dynamics of the model, which enables stochastic bounds of FK measures between two inhomegenous percolations. We also prove uniqueness of the infinite-volume measure in our extended ranges. Most of our results are valid in any dimension $d \geq 2$ and beyond hypercubic lattices.
format Preprint
id arxiv_https___arxiv_org_abs_2512_16486
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A new bound for the critical point of the FK model for $q<1$
Beffara, Vincent
Faipeur, Corentin
Oke, Tejas
Probability
Mathematical Physics
We consider the random cluster model with parameter $q<1$, for which the FKG inequalities are not valid. On the square lattice, stochastic comparison with Bernoulli percolation implies that the model is subcritical (respectively supercritical) when $p \leq q/(1+q)$ (resp. $p \geq 1/2$); in this paper, we extend these two regions, by improving the classical stochastic comparisons. Assuming the existence of the critical point, this reduces its possible range. The proof relies on a modification of the usual Glauber dynamics of the model, which enables stochastic bounds of FK measures between two inhomegenous percolations. We also prove uniqueness of the infinite-volume measure in our extended ranges. Most of our results are valid in any dimension $d \geq 2$ and beyond hypercubic lattices.
title A new bound for the critical point of the FK model for $q<1$
topic Probability
Mathematical Physics
url https://arxiv.org/abs/2512.16486