Work

One- and Two-Particle Spectral Gap Identities for the Symmetric Inclusion Process and Related Models

Year: 2026

Type: article

Abstract: The symmetric inclusion process (SIP) models particles diffusing on a graph with mutual attraction. We recently showed [KS24] that, in the log-concave regime (where diffusivity dominates interaction), the spectral gap of the conservative SIP matches that of a single particle. In this paper, our main result demonstrates that this identity generally fails outside this regime, but always holds for the non-conservative SIP, regardless of the interaction strength. When this one-particle spectral gap identity breaks down, we derive sharp bounds for the gap in terms of diffusivity, and reveal a two-particle spectral gap identity in the vanishing diffusivity limit. Our approach leverages the rigid eigenstructure of SIP, refined comparisons of Dirichlet forms for arbitrary diffusivity and particle numbers, and techniques from slow–fast system analysis. These findings extend to the dual interacting diffusion known as Brownian energy process, and shed some light on the spectral gap behavior for related Dirichlet-reversible systems on general, non-mean-field, geometries.

Source: Communications in Mathematical Physics

DOI: 10.1007/s00220-026-05728-9

Authors: Seonwoo Kim, Federico Sau

Institutions: Yonsei University, University of Milan

Language: English

Topic: Stochastic processes and statistical mechanics

Subfield: Mathematical Physics

Field: Mathematics

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,990