Calculus of Variations and Geometric Measure Theory

Andrei A. Agrachev - S. Baranzini - E. Bellini - L. Rizzi

Quantitative tightness for three-dimensional contact manifolds: a sub-Riemannian approach

created by rizzi1 on 02 Jul 2024



Inserted: 2 jul 2024

Year: 2024

ArXiv: 2407.00770 PDF


Through the use of sub-Riemannian metrics we provide quantitative estimates for the maximal tight neighbourhood of a Reeb orbit on a three-dimensional contact manifold. Under appropriate geometric conditions we show how to construct closed curves which are boundaries of overtwisted disks. We introduce the concept of contact Jacobi curve, and prove sharp lower bounds of the so-called tightness radius (from a Reeb orbit) in terms of Schwarzian derivative bounds. We also prove similar, but non-sharp, comparison theorems in terms of sub-Riemannian canonical curvature bounds. We apply our results to K-contact sub-Riemannian manifolds. In this setting, we prove a contact analogue of the celebrated Cartan-Hadamard theorem.