Curves and surfaces making a constant angle with a parallel transported direction in Riemannian spaces

Fuente: arXiv
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Main Authors: da Silva, Luiz C. B., Ferreira Jr, Gilson S., da Silva, José D.
Format: Preprint
Published: 2024
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_version_ 1866917614957101056
author da Silva, Luiz C. B.
Ferreira Jr, Gilson S.
da Silva, José D.
author_facet da Silva, Luiz C. B.
Ferreira Jr, Gilson S.
da Silva, José D.
contents In the last two decades, much effort has been dedicated to studying curves and surfaces according to their angle with a given direction. However, most findings were obtained using a case-by-case approach, and it is often unclear what are consequences of the specificities of the ambient manifold and what could be generic. In this work, we propose a theoretical framework to unify parts of these findings. We study curves and surfaces by prescribing the angle they make with a parallel transported vector field. We show that the characterization of Euclidean helices in terms of their curvature and torsion is also valid in any Riemannian manifold. Among other properties, we prove that surfaces making a constant angle with a parallel transported direction are extrinsically flat ruled surfaces. We also investigate the relation between their geodesics and the so-called slant helices; we prove that surfaces of constant angle are the rectifying surface of a slant helix, i.e., the ruled surface with rulings given by the Darboux vector field of the directrix. We characterize rectifying surfaces of constant angle; in other words, when their geodesics are slant helices. As a corollary, we show that if every geodesic of a surface of constant angle is a slant helix, then the ambient manifold is flat. Finally, we characterize surfaces in the product of a Riemannian surface with the real line making a constant angle with the vertical real direction.
format Preprint
id arxiv_https___arxiv_org_abs_2403_10716
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Curves and surfaces making a constant angle with a parallel transported direction in Riemannian spaces
da Silva, Luiz C. B.
Ferreira Jr, Gilson S.
da Silva, José D.
Differential Geometry
53A04, 53A05, 53A35, 53B25
In the last two decades, much effort has been dedicated to studying curves and surfaces according to their angle with a given direction. However, most findings were obtained using a case-by-case approach, and it is often unclear what are consequences of the specificities of the ambient manifold and what could be generic. In this work, we propose a theoretical framework to unify parts of these findings. We study curves and surfaces by prescribing the angle they make with a parallel transported vector field. We show that the characterization of Euclidean helices in terms of their curvature and torsion is also valid in any Riemannian manifold. Among other properties, we prove that surfaces making a constant angle with a parallel transported direction are extrinsically flat ruled surfaces. We also investigate the relation between their geodesics and the so-called slant helices; we prove that surfaces of constant angle are the rectifying surface of a slant helix, i.e., the ruled surface with rulings given by the Darboux vector field of the directrix. We characterize rectifying surfaces of constant angle; in other words, when their geodesics are slant helices. As a corollary, we show that if every geodesic of a surface of constant angle is a slant helix, then the ambient manifold is flat. Finally, we characterize surfaces in the product of a Riemannian surface with the real line making a constant angle with the vertical real direction.
title Curves and surfaces making a constant angle with a parallel transported direction in Riemannian spaces
topic Differential Geometry
53A04, 53A05, 53A35, 53B25
url https://arxiv.org/abs/2403.10716