The real layering field of Brownian loop soup and the Gaussian multiplicative chaos
Sayantan Maitra
TL;DR
The paper analyzes the real-valued layering field arising from the Brownian loop soup in a bounded domain and proves that, after renormalization, it converges to the subcritical Gaussian multiplicative chaos (GMC) as $\lambda \to \infty$ and $\beta \to 0$ with $\lambda\beta^2\to\xi^2$. It builds two parallel objects—the Poisson layering field $V_{\lambda,\beta,D}$ and the Gaussian layering field $W_{\xi,D}$—and establishes their existence, correlation structure, and conformal covariance, using Wiener–Itô chaos expansions as a central tool. The main result is that the Poisson layering field converges in finite-dimensional distributions to the Gaussian layering field in the subcritical regime, thereby connecting loop-soup layering to GMC in the real-valued setting and enriching the correspondence previously known for the imaginary layering field. The work complements prior imaginary-layering results by providing a rigorous real-valued framework and highlights the role of renormalization and chaos expansions in bridging probabilistic loop-soup constructions with GMC theory under conformal settings.
Abstract
We consider the random field defined by the layering numbers of the Brownian loop soup in a bounded simply connected domain in the complex plane. We call this the layering field and show that, after a suitable renormalization, it converges to the subcritical Gaussian multiplicative chaos. The main technique for our proof is the Wiener-Itô chaos expansion. We also calculate the $n$-point functions of the layering field, show their conformal covariance and discuss their behavior near the boundary of the domain.
