The Integrable Snake Model

TL;DR

This paper introduces an integrable probabilistic model called the pure snake configuration, generalizing lozenge tilings, and explores its properties, scaling limits, and applications to asymmetric simple exclusion processes.

Contribution

It defines a new integrable model extending lozenge tilings, provides explicit formulas for its partition and correlation functions, and applies it to ASEP traffic representations.

Findings

Explicit formulas for partition and correlation functions.

Scaling limits connect the model to ASEP.

Generalization of TASEP traffic representation.

Abstract

A pure snake configuration is a bijection $\sigma:\mathbb{Z}^2 \to \mathbb{Z}^2$ containing no two-cycles and such that for each $x \in \mathbb{Z}^2$ we have $\sigma(x) \in \{ x , x+ \mathbf{e}^1, x+\mathbf{e}^2 , x- \mathbf{e}^2 \}.$ The non-trivial cycles of a pure snake configuration may be regarded as a collection of non-intersecting paths in $\mathbb{Z}^2$ that may travel right, up, or down (but not left) from a given vertex. Pure snake configurations are a generalisation of lozenge tilings, which are in natural correspondence with paths that only travel right or up. We introduce a partition function on a finite version of this model and study the probabilistic properties of random pure snake configurations chosen according to their contribution to this partition function. Under a suitable weighting, the model is integrable in the sense that we have access to explicit formulas for its partition function and correlation function. We utilise the integrable structure of this model in several applications through its various scaling limits, such as to prove a traffic representation of ASEP on the ring, generalising the analogous result for TASEP by the first author.