Lattice random walks and quantum A-period conjecture

Abstract

We derive explicit closed-form expressions for the generating function $C_N(A)$, which enumerates classical closed random walks on square and triangular lattices with $N$ steps and a signed area $A$, characterized by the number of moves in each hopping direction. This enumeration problem is mapped to the trace of powers of anisotropic Hofstadter-like Hamiltonian and is connected to the cluster coefficients of exclusion particles: exclusion strength parameter $g=2$ for square lattice walks, and a mixture of $g=1$ and $g=2$ for triangular lattice walks. By leveraging the intrinsic link between the Hofstadter model and high energy physics, we propose a conjecture connecting the above signed area enumeration $C_N(A)$ in statistical mechanics to the quantum A-period of associated toric Calabi-Yau threefold in topological string theory: square lattice walks correspond to local ${\mathbb{F}}_0$ geometry, while triangular lattice walks are associated with local ${\mathcal{B}}_3$.

21 pages, 2 figures, 2 tables; minor revisions and typo corrections; submitted to SciPost Physics