arXiv subjects

Arielle Marc-Zwecker

Publications and source records attributed to Arielle Marc-Zwecker.

2 recordsLinked to original sources

arXiv2025

Horn's problem in PU$(n,1)$

The multiplicative Horn problem is the following question: given three conjugacy classes $\mathcal{C}_1, \mathcal{C}_2, \mathcal{C}_3$ in a Lie group $G$, do there exist elements $(A,B,C)\in\mathcal{C}_1\times\mathcal{C}_2\times\mathcal{C}_3$ such that $ABC=\operatorname{Id}$? In this paper, we study the multiplicative Horn problem restricted to the elliptic classes of the group $G={\rm PU}(n,1)$ for $n\geq 1$, which is the isometry group of the $n$-dimensional complex hyperbolic space. We show that the solution set of Horn's problem in PU$(n,1)$ is a finite union of convex polytopes in the space of elliptic conjugacy classes. We give a complete description of these polytopes when $n=2$.

math.GT↗

arXiv2023

Triangle groups in the complex hyperbolic plane and special fibers of the momentum map in PU(2,1)

In this work, we consider relative character varieties for representations of the 3-punctured sphere group in PU(2,1). We provide necessary and sufficient conditions on the peripheral conjugacy classes, for such a representation to admit a decomposition as products of special elliptic elements. We prove that the representations satisfying these conditions form fibers of the so-called momentum map for PU(2,1). We apply these results to representations of the even subgroup of triangle groups, and describe components of the associated character variety.

math.DG↗