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Abderrahim Mesbah

Publications and source records attributed to Abderrahim Mesbah.

6 recordsLinked to original sources

Harmonic extension of Weil-Petersson circle homeomorphisms

In this paper, we study Weil--Petersson circle homeomorphisms from the viewpoint of harmonic maps. We prove that a homeomorphism $\varphi:\mathbb S^1\to\mathbb S^1$ is Weil--Petersson if and only if its unique quasiconformal harmonic extension to the hyperbolic disk $\mathbb D$ has square-integrable Beltrami differential. Our approach is based on the anti-holomorphic $L^2$-energy of harmonic maps. We show that this energy is finite for the quasiconformal harmonic extension of every Weil--Petersson circle homeomorphism, and that, among suitable quasiconformal extensions, the harmonic extension minimizes this energy.

math.DG

Domination between non-Fuchsian representations and anti-de Sitter geometry

Motivated by work of various authors on domination between surface group representations, harmonic maps, and $3$-dimensional anti-de Sitter geometry, we study a new domination problem between non-Fuchsian representations of closed surface groups. We solve the problem for representations that admit branched harmonic immersions, and we show that, outside of this case, the problem cannot always be solved. We then show that a dominating pair gives rise to an anti-de Sitter $3$-manifold with singularities, and we construct large families of branched anti-de Sitter $3$-manifolds.

math.DG

Embedded convex surfaces in hyperbolic and anti-de Sitter spaces

We show that given a quasi-circle $C \subset \partial_\infty \mathbb{H}^3$ (respectively $C \subset \partial_\infty \mathbb{A}\mathbb{D}\mathbb{S}^3$) and a complete conformal metric $h$ on $\mathbb{D}$ whose curvature $K_h$ takes values in a compact subset of $(-1,0)$ (respectively $(-\infty,-1)$), with all derivatives bounded with respect to the hyperbolic metric, there exists a smooth isometric embedding $V : (\mathbb{D},h) \to \mathbb{H}^3$ (respectively $V : (\mathbb{D},h) \to \mathbb{A}\mathbb{D}\mathbb{S}^3$) such that $V$ extends continuously to a homeomorphism $\partial V : \mathbb{S}^1 \to C$. In the hyperbolic case, the conclusion still holds if $C$ is an arbitrary Jordan curve.

math.DG

The Prescribed Metric on Convex Subsets of Anti-de Sitter Space with Quasi-Circle Ideal Boundaries

Let $h^{+}$ and $h^{-}$ be two complete, conformal metrics on the disc $\mathbb{D}$. Assume moreover that the derivatives of the conformal factors of the metrics $h^{+}$ and $h^{-}$ are bounded at any order with respect to the hyperbolic metric, and that the metrics have curvatures in the interval $\left(-\frac{1}ε, -1 - ε\right)$, for some $ε> 0$. Let $f$ be a quasi-symmetric map. We show the existence of a globally hyperbolic convex subset $Ω$ (see Definition 4.1) of the three-dimensional anti-de Sitter space, such that $Ω$ has $h^{+}$ (respectively $h^{-}$) as the induced metric on its future boundary (respectively on its past boundary) and has a gluing map $Φ_Ω$ (see Definition 5.7) equal to $f$.

math.DG

The induced metric and bending lamination on the boundary of convex hyperbolic 3-manifolds

Let $S$ be an oriented closed surface of genus at least two, and let $M = S \times (0,1)$. Suppose that $h$ is a Riemannian metric on $S$ with curvature strictly greater than $-1$, $h^{*}$ is a Riemannian metric on $S$ with curvature strictly less than $1$, and every contractible closed geodesic with respect to $h^{*}$ has length strictly greater than $2π$. Let $μ$ be a measured lamination on $S$ such that every closed leaf has weight strictly less than $π$. Then, we prove the existence of a convex hyperbolic metric $g$ on the interior of $M$ that induces the Riemannian metric $h$ (respectively $h^{*}$) as the first (respectively third) fundamental form on $S \times \left\{ 0\right\}$ and induces a pleated surface structure on $S \times \left\{ 1\right\}$ with bending lamination $μ$. This statement remains valid even in limiting cases where the curvature of $h$ is constant and equal to $-1$. Additionally, when considering a conformal class $c$ on $S$, we show that there exists a convex hyperbolic metric $g$ on the interior of $M$ that induces $c$ on $S \times \left\{ 0\right\}$, which is viewed as one component of the ideal boundary at infinity of $(M,g)$, and induces a pleated surface structure on $S \times \left\{ 1\right\}$ with bending lamination $μ$. Our proof differs from previous work by Lecuire for these two last cases. Moreover, when we consider a lamination which is small enough, in a sense that we will define, and a hyperbolic metric, we show that the metric on the interior of $M$ that realizes these data is unique.

math.GT

Asymptotic behavior of Moncrief Lines in constant curvature space-times

We study the asymptotic behavior of Moncrief lines on $2+1$ maximal globally hyperbolic spatially compact space-time $M$ of non-negative constant curvature. We show that when the unique geodesic lamination associated with $M$ is either maximal uniquely ergodic or simplicial, the Moncrief line converges, as time goes to zero, to a unique point in the Thurston boundary of the Teichmüller space.

math.GT