Abstract
Let \(D\subset \mathbb{R}^d\) be a bounded Lipschitz domain, let \(\omega\) be a modulus of continuity of a high order of smoothness, and let \(T\) be a Calderón–Zygmund convolution operator with even kernel. Using the recent T(P) boundedness criterion found by the author with E. Doubtsov, we prove that the operator \(T\) is bounded in the Zygmund space \(\mathcal{C}_{\omega}(D)\) if the smoothness of the boundary of \(D\) is by one higher than that of \(\mathcal{C}_{\omega}(D)\) . The proof is based on estimates for the potentials with Calderón–Zygmund kernels of the characteristic function of a domain with a polynomial boundary.