Fluctuations in random field Ising models
Seunghyun Lee, Nabarun Deb, Sumit Mukherjee
TL;DR
The paper studies fluctuations of linear statistics $T_n=\mathbf q^\top\boldsymbol\sigma$ under quadratic interaction Gibbs measures in the high-temperature regime, focusing on non-asymptotic Berry-Esseen bounds. It develops a unified LLN/CLT framework centered by the Mean-Field optimizer $\mathbf u$, with CLTs expressed in terms of an approximate eigenpair $\mathbf A_n\mathbf q\approx\lambda_n\mathbf q$ and variance $\upsilon_n/(1-\lambda_n\upsilon_n)$. The results cover RFIM on diverse graph ensembles (ER, regular, graphons) and Hopfield models, providing both quenched and annealed limits and extending CLTs to non-regular, possibly spin-glass–like settings. The methodology combines Stein's method of exchangeable pairs with Chevet-type concentration inequalities to handle general $\mathbf A_n$ and inhomogeneous fields, yielding explicit non-asymptotic error bounds and broad applicability to quadratic interaction models.
Abstract
This paper establishes a CLT for linear statistics of the form $\langle \mathbf{q},\boldsymbolσ \rangle$ with quantitative Berry-Esseen bounds, where $\boldsymbolσ$ is an observation from an exponential family with a quadratic form as its sufficient statistic, in the \enquote{high-temperature} regime. We apply our general result to random field Ising models with both discrete and continuous spins. To demonstrate the generality of our techniques, we apply our results to derive both quenched and annealed CLTs in various examples, which include Ising models on some graph ensembles of common interest (Erdős-Rényi, regular, dense bipartite), and the Hopfield spin glass model. Our proofs rely on a combination of Stein's method of exchangeable pairs and Chevet type concentration inequalities.
