# Perturbations of elliptic operators in 1-sided chord-arc domains. Part II: Non-symmetric operators and Carleson measure estimates

## TL;DR

This paper extends the understanding of elliptic operators in 1-sided chord-arc domains, showing Carleson measure estimates imply the elliptic measure is in A_infinity, with applications to perturbation and symmetry conditions.

## Contribution

It generalizes previous results to non-symmetric operators, simplifies proofs, and establishes new equivalences between elliptic measure properties and domain geometry.

## Key findings

- Carleson measure estimates imply elliptic measure in A_infinity.
- Extension of perturbation results to non-symmetric coefficients.
- Equivalence of A_infinity membership for operators and their transposes under Carleson conditions.

## Abstract

We generalize to the setting of 1-sided chord-arc domains, that is, to domains satisfying the interior Corkscrew and Harnack Chain conditions (these are respectively scale-invariant/quantitative versions of the openness and path-connectedness) and which have an Ahlfors regular boundary, a result of Kenig-Kirchheim-Pipher-Toro, in which Carleson measure estimates for bounded solutions of the equation $Lu=-{\rm div}(A\nabla u) = 0$ with $A$ being a real (not necessarily symmetric) uniformly elliptic matrix, imply that the corresponding elliptic measure belongs to the Muckenhoupt $A_\infty$ class with respect to surface measure on the boundary. We present two applications of this result. In the first one we extend a perturbation result recently proved by Cavero-Hofmann-Martell presenting a simpler proof and allowing non-symmetric coefficients. Second, we prove that if an operator $L$ as above has locally Lipschitz coefficients satisfying certain Carleson measure condition then $\omega_L\in A_\infty$ if and only if $\omega_{L^\top}\in A_\infty$. As a consequence, we can remove one of the main assumptions in the non-symmetric case of a result of Hofmann-Martell-Toro and show that if the coefficients satisfy a slightly stronger Carleson measure condition the membership of the elliptic measure associated with $L$ to the class $A_\infty$ yields that the domain is indeed a chord-arc domain.