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arXiv · 2603.26157

Exponential decay of correlations at high temperature in $H^{2|2n}$ nonlinear sigma models

Margherita Disertori·Javier Durán Fernández·Luca Fresta
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Abstract

We consider a family of nonlinear sigma models on $\mathbb{Z}^{d}$ whose target space is the hyperbolic super manifold $H^{2|2n}$, $n >1$, introduced by Crawford as an extension of Zirnbauer's $H^{2|2}$ model for disordered systems. We prove exponential decay of the two-point correlation function in the high-temperature regime $\beta \leq C n^{-1}$, with $C>0$ a universal constant, for any $n>1$ and any dimension $d\geq 1$, with mass $\log \beta^{-1}$. We also consider models with long-range interaction and prove fast decay in the same high-temperature regime. The proof is based on the reduction to a marginal fermionic theory and combines a high-temperature cluster expansion, exact combinatorics and bounds derived via Grassmann norms.

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Margherita Disertori, Javier Durán Fernández, Luca Fresta. 2026-03-27. Exponential decay of correlations at high temperature in $H^{2|2n}$ nonlinear sigma models. https://arxiv.org/abs/2603.26157

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