Quantitative statistical stability for the equilibrium states of piecewise partially hyperbolic maps
Rafael Bilbao, Ricardo Bioni, Rafael Lucena
TL;DR
The paper addresses how equilibrium states for a class of skew-product maps $F=(f,G)$, with a non-uniformly expanding base and a contracting fiber, respond to deterministic perturbations. It develops an anisotropic space $S^\infty$ for disintegrated measures and harnesses Hölder regularity of disintegration to obtain a spectral-gap framework for the transfer operator $\mathrm{F}_*$, enabling quantitative statistical stability. The authors prove existence and uniqueness of the invariant measure in $S^\infty$ and establish exponential convergence to equilibrium, then formulate and apply a perturbation theory via an $(R({\cdot}), {\cdot})$-family of operators to obtain a modulus of continuity $O(\delta^{\zeta}\log \delta)$ for the perturbed invariant measures. This yields precise, rate-based stability results for a broad class of deterministic perturbations, contributing to the understanding of uncertainty propagation in complex non-invertible partially hyperbolic systems.
Abstract
We consider a class of endomorphisms that contains a set of piecewise partially hyperbolic dynamics semi-conjugated to non-uniformly expanding maps. Our goal is to study a class of endomorphisms that preserve a foliation that is almost everywhere uniformly contracted, with possible discontinuity sets parallel to the contracting direction. We apply the spectral gap property and the $ζ$-Hölder regularity of the disintegration of its equilibrium states to prove a quantitative statistical stability statement. More precisely, under deterministic perturbations of the system of size $δ$, we show that the $F$-invariant measure varies continuously with respect to a suitable anisotropic norm. Moreover, we prove that for certain interesting classes of perturbations, its modulus of continuity is $O(δ^ζ\log δ)$. This article has been accepted for publication in the Discrete and Continuous Dynamical Systems journal.
