Estimates for the maximal Cauchy integral on chord-arc curves

Abstract

We study the chord-arc Jordan curves that satisfy the Cotlar-type inequality $T_*(f)\lesssim M^2(Tf),$ where $T$ is the Cauchy transform, $T_*$ is the maximal Cauchy transform and $M$ is the Hardy-Littlewood maximal function. Under the background assumption of asymptotic quasi-conformality we find a characterization of such curves in terms of the smoothness of a parametrization of the curve.