Domain wall partition functions and KP

TL;DR

This paper reveals that the partition function of the six vertex model with domain wall boundary conditions can be represented as a KP tau function and expressed using free fermion expectation values.

Contribution

It establishes a novel connection between the six vertex model's partition function and integrable systems via KP tau functions and free fermion formalism.

Findings

Partition function is a KP tau function.

Expressed as an expectation value of free fermions.

Provides a new integrable systems perspective.

Abstract

We observe that the partition function of the six vertex model on a finite square lattice with domain wall boundary conditions is (a restriction of) a KP tau function and express it as an expectation value of charged free fermions (up to an overall normalization).