The analyticity domains of the Lindstedt series for the standard map are studied numerically using Pad'e approximants to model their natural boundaries. We show that if the rotation number is a Diophantine number close to a rational value p/q, then the radius of convergence of the Lindstedt series becomes smaller than the critical threshold for the corresponding Kol’mogorov-Arnol’d-Moser curve, and the natural boundary on the plane of the complexified perturbative parameter acquires a flowerlike shape with 2q petals.
Berretti, A., Falcolini, C., & Gentile, G. (2001). Shape of analyticity domains of Lindstedt series: the standard map. PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS, 64(1), 015101.1-015101.4 [10.1103/PhysRevE.64.015202].