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Fábio R. dos Santos

Publications and source records attributed to Fábio R. dos Santos.

3 recordsLinked to original sources

Non-degenerate anisocurved surfaces in homogeneous 3-manifolds

In this manuscript we consider non-degenerate surfaces $Σ^2$ immersed in a 3-dimensional homogeneous space $\mathbb{L}^3(κ,τ)$ endowed with two different metrics, the one induced by the Riemannian metric of $\mathbb{E}^3(κ,τ)$ and the non-degenerate metric inherited by the Lorentzian one of $\mathbb{L}^3(κ,τ)$. Therefore, we have two different geometries on $Σ^2$ and we can compare them. In particular, we can consider the Gaussian curvature functions which respect to both metrics and study the geometry of the surfaces satisfying that both Gaussian curvature functions are opposite. We will call these surfaces anisocurved surfaces. In order to obtain our main results we also need to impose some extra assumptions regarding the extrinsic curvatures with respect to both metrics.

math.DG↗

Willmore surfaces and Hopf tori in homogeneous 3-manifolds

Some classification results for closed surfaces in Berger spheres are presented. On the one hand, a Willmore functional for isometrically immersed surfaces into an homogeneous space $\mathbb{E}^{3}(κ,τ)$ with isometry group of dimension $4$ is defined and its first variational formula is computed. Then, we characterize Clifford and Hopf tori as the only Willmore surfaces satifying a sharp Simons-type integral inequality. On the other hand, we also obtain some integral inequalities for closed surfaces with constant extrinsic curvature in $\mathbb{E}^3(κ,τ)$, becoming equalities if and only if the surface is a Hopf torus in a Berger sphere.

math.DG↗

Total mean curvature surfaces in the product space $\mathbb{S}^n\times\mathbb{R}$ and applications

The total mean curvature functional for submanifolds into the Riemannian product space $\mathbb{S}^n\times\mathbb{R}$ is considered and its first variational formula is presented. Later on, two second order differential operators are defined and a nice integral inequality relating both of them is proved. Finally we prove our main result: an integral inequality for closed stationary $\mathcal{H}$-surfaces in $\mathbb{S}^n\times\mathbb{R}$, characterizing the cases where the equality is attained.

math.DG↗