A non-trivial family of trivial bundles with complex hyperbolic structure

Fuente: arXiv
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Main Authors: Botós, Hugo C., Franco, Felipe A.
Format: Preprint
Published: 2024
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author Botós, Hugo C.
Franco, Felipe A.
author_facet Botós, Hugo C.
Franco, Felipe A.
contents In $\mathrm{PU}(2,1)$, the group of holomorphic isometries of the complex hyperbolic plane, we study the space of involutions $R_1, R_2, R_3, R_4, R_5$ satisfying $R_5R_4R_3R_2R_1=1$, where $R_1$ is a reflection in a complex geodesic and the other $R_i$'s are reflections in points of the complex hyperbolic plane. We show that this space modulo $\mathrm{PU}(2,1)$-conjugation is bending-connected and has dimension $4$. Using this, we construct a $4$-dimensional bending-connected family of complex hyperbolic structures on a disc orbibundle with vanishing Euler number over the sphere with $5$ cone points of angle $π$. Bending-connectedness here means that we can naturally deform the geometric structure, like Dehn twists in Teichmüller theory. Additionally, finding complex hyperbolic disc orbibundles with vanishing Euler number is a hard problem, originally conjectured by W. Goldman and Y. Eliashberg and solved by S. Anan'in and N. Gusevskii, and we produce a simpler and more straightforward construction for them.
format Preprint
id arxiv_https___arxiv_org_abs_2411_02213
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A non-trivial family of trivial bundles with complex hyperbolic structure
Botós, Hugo C.
Franco, Felipe A.
Geometric Topology
Differential Geometry
57S30 (Primary) 51M10, 57M50, 57R18 (Secondary)
In $\mathrm{PU}(2,1)$, the group of holomorphic isometries of the complex hyperbolic plane, we study the space of involutions $R_1, R_2, R_3, R_4, R_5$ satisfying $R_5R_4R_3R_2R_1=1$, where $R_1$ is a reflection in a complex geodesic and the other $R_i$'s are reflections in points of the complex hyperbolic plane. We show that this space modulo $\mathrm{PU}(2,1)$-conjugation is bending-connected and has dimension $4$. Using this, we construct a $4$-dimensional bending-connected family of complex hyperbolic structures on a disc orbibundle with vanishing Euler number over the sphere with $5$ cone points of angle $π$. Bending-connectedness here means that we can naturally deform the geometric structure, like Dehn twists in Teichmüller theory. Additionally, finding complex hyperbolic disc orbibundles with vanishing Euler number is a hard problem, originally conjectured by W. Goldman and Y. Eliashberg and solved by S. Anan'in and N. Gusevskii, and we produce a simpler and more straightforward construction for them.
title A non-trivial family of trivial bundles with complex hyperbolic structure
topic Geometric Topology
Differential Geometry
57S30 (Primary) 51M10, 57M50, 57R18 (Secondary)
url https://arxiv.org/abs/2411.02213