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Nesting of double-dimer loops: local fluctuations and convergence to the nesting field of CLE(4)

Mikhail Basok, Konstantin Izyurov

TL;DR

This work proves two central results about the double-dimer model in the upper half-plane: first, at a fixed bulk point $v$, the number of encircling double-dimer loops $N_{\delta}(v)$ satisfies a central limit theorem with $\mu_{\delta}=-\frac{1}{\pi^{2}}\log\delta+O(1)$ and $\sigma_{\delta}^{2}= -\frac{2}{3\pi^{2}}\log\delta+O(1)$, so $(N_{\delta}(v)-\mu_{\delta})/\sigma_{\delta} \Rightarrow \mathcal{N}(0,1)$; second, the nesting field $\varphi_{\delta}=N_{\delta}-\mathbb{E}N_{\delta}$ converges in distribution to the CLE${}_4$ nesting field $\varphi$ in the local Sobolev space $H^{-1-\nu}_{\mathrm{loc}}(\mathbb{C}^{+})$ for every $\nu>0$. The authors achieve this via a monodromy-enhanced Kasteleyn framework to control near-diagonal asymptotics of inverse operators, coupled with approximate Wick's rules for height fluctuations and meticulous regularization of nested loop observables. They then embed these discrete results into a Sobolev-field setting, develop a two-point approximation for CLE nesting fields, and leverage cylindrical-event convergence results for CLE${}_4$ to conclude the full nesting-field convergence of the double-dimer model. The work thus solidifies a path toward the full convergence of double-dimer loop laminations to CLE${}_4$ by establishing the Gaussian fluctuations and the Sobolev-continuity of nesting fields. Overall, it provides a rigorous link between discrete dimer observables and the conformal loop ensemble nesting fields, with explicit constants and a robust multiscale analytic framework.

Abstract

We consider the double-dimer model in the upper-half plane discretized by the square lattice with mesh size $δ$. For each point $x$ in the upper half-plane, we consider the random variable $N_δ(x)$ given by the number of the double-dimer loops surrounding this point. We prove that the normalized fluctuations of $N_δ(x)$ for a fixed $x$ are asymptotically Gaussian as $δ\to 0+$. Further, we prove that the double-dimer nesting field $N_δ(\cdot) - \mathbb{E}\, N_δ(\cdot)$, viewed as a random distribution in the upper half-plane, converges as $δ\to 0+$ to the nesting field of CLE(4) constructed by Miller, Watson and Wilson.

Nesting of double-dimer loops: local fluctuations and convergence to the nesting field of CLE(4)

TL;DR

This work proves two central results about the double-dimer model in the upper half-plane: first, at a fixed bulk point , the number of encircling double-dimer loops satisfies a central limit theorem with and , so ; second, the nesting field converges in distribution to the CLE nesting field in the local Sobolev space for every . The authors achieve this via a monodromy-enhanced Kasteleyn framework to control near-diagonal asymptotics of inverse operators, coupled with approximate Wick's rules for height fluctuations and meticulous regularization of nested loop observables. They then embed these discrete results into a Sobolev-field setting, develop a two-point approximation for CLE nesting fields, and leverage cylindrical-event convergence results for CLE to conclude the full nesting-field convergence of the double-dimer model. The work thus solidifies a path toward the full convergence of double-dimer loop laminations to CLE by establishing the Gaussian fluctuations and the Sobolev-continuity of nesting fields. Overall, it provides a rigorous link between discrete dimer observables and the conformal loop ensemble nesting fields, with explicit constants and a robust multiscale analytic framework.

Abstract

We consider the double-dimer model in the upper-half plane discretized by the square lattice with mesh size . For each point in the upper half-plane, we consider the random variable given by the number of the double-dimer loops surrounding this point. We prove that the normalized fluctuations of for a fixed are asymptotically Gaussian as . Further, we prove that the double-dimer nesting field , viewed as a random distribution in the upper half-plane, converges as to the nesting field of CLE(4) constructed by Miller, Watson and Wilson.
Paper Structure (16 sections, 46 theorems, 255 equations)