Occupation times of long-range exclusion and connections to KPZ class exponents

TL;DR

This paper investigates the fluctuation behavior of occupation times in long-range exclusion processes, revealing connections to fractional Brownian motions and KPZ class scalings depending on parameters like , d, and .

Contribution

It provides a detailed analysis of variance scaling and fluctuation limits for long-range exclusion processes, highlighting a dichotomy based on the long-range parameter  and linking to KPZ universality.

Findings

Symmetric case yields fractional Brownian motion limits with Hurst parameter in [1/2, 3/4].

Asymmetric case shows a variance dichotomy at =3/2, with different scaling behaviors.

Results connect long-range exclusion processes to KPZ class fluctuations in certain regimes.

Abstract

With respect to a class of long-range exclusion processes on $\mathbb{Z}^d$, with single particle transition rates of order $|\cdot|^{-(d+\alpha)}$, starting under Bernoulli invariant measure $\nu_\rho$ with density $\rho$, we consider the fluctuation behavior of occupation times at a vertex and more general additive functionals. Part of our motivation is to investigate the dependence on $\alpha$, $d$ and $\rho$ with respect to the variance of these functionals and associated scaling limits. In the case the rates are symmetric, among other results, we find the scaling limits exhaust a range of fractional Brownian motions with Hurst parameter $H\in [1/2,3/4]$. However, in the asymmetric case, we study the asymptotics of the variances, which when $d=1$ and $\rho=1/2$ points to a curious dichotomy between long-range strength parameters $0<\alpha\leq 3/2$ and $\alpha>3/2$. In the former case, the order of the occupation time variance is the same as under the process with symmetrized transition rates, which are calculated exactly. In the latter situation, we provide consistent lower and upper bounds and other motivations that this variance order is the same as under the asymmetric short-range model, which is connected to KPZ class scalings of the space-time bulk mass density fluctuations.