Curvature measures and the sub-Riemannian Gauss-Bonnet theorem

Fuente: arXiv
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Main Authors: Barilari, Davide, Bellini, Eugenio, Pinamonti, Andrea
Format: Preprint
Published: 2025
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author Barilari, Davide
Bellini, Eugenio
Pinamonti, Andrea
author_facet Barilari, Davide
Bellini, Eugenio
Pinamonti, Andrea
contents We adopt a measure-theoretic perspective on the Riemannian approximation scheme proving a sub-Riemannian Gauss-Bonnet theorem for surfaces in 3D contact manifolds. We show that the zero-order term in the limit is a singular measure supported on isolated characteristic points. In particular, this provides a unified interpretation of previous results. Moreover we give natural geometric conditions under which our result holds, namely when the surface admits characteristic points of finite order of degeneracy. This notion, which we introduce, extends the concept of mildly degenerate characteristic points for the Heisenberg group. As a byproduct, we prove that the mean curvature around an isolated characteristic point of finite order of degeneracy is locally integrable. In particular, this positively answers a question for analytic surfaces in every analytic 3D contact manifold.
format Preprint
id arxiv_https___arxiv_org_abs_2509_26460
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Curvature measures and the sub-Riemannian Gauss-Bonnet theorem
Barilari, Davide
Bellini, Eugenio
Pinamonti, Andrea
Differential Geometry
We adopt a measure-theoretic perspective on the Riemannian approximation scheme proving a sub-Riemannian Gauss-Bonnet theorem for surfaces in 3D contact manifolds. We show that the zero-order term in the limit is a singular measure supported on isolated characteristic points. In particular, this provides a unified interpretation of previous results. Moreover we give natural geometric conditions under which our result holds, namely when the surface admits characteristic points of finite order of degeneracy. This notion, which we introduce, extends the concept of mildly degenerate characteristic points for the Heisenberg group. As a byproduct, we prove that the mean curvature around an isolated characteristic point of finite order of degeneracy is locally integrable. In particular, this positively answers a question for analytic surfaces in every analytic 3D contact manifold.
title Curvature measures and the sub-Riemannian Gauss-Bonnet theorem
topic Differential Geometry
url https://arxiv.org/abs/2509.26460