English

Uniruledness of some low-dimensional ball quotients

Number Theory 2024-03-06 v5 Algebraic Geometry

Abstract

We define reflective modular forms on complex balls and use a method of Gritsenko and Hulek to show that some ball quotients of dimensions 3, 4 and 5 are uniruled. We give examples of Hermitian lattices over the rings of integers of imaginary quadratic fields Q(1)\mathbb{Q}(\sqrt{-1}) and Q(2)\mathbb{Q}(\sqrt{-2}) for which the associated ball quotients are uniruled. Our examples include the moduli space of 8 points on P1\mathbb{P}^1. Moreover, we find that some of their Satake-Baily-Borel compactifications are rationally chain connected modulo certain cusps.

Keywords

Cite

@article{arxiv.2008.13106,
  title  = {Uniruledness of some low-dimensional ball quotients},
  author = {Yota Maeda},
  journal= {arXiv preprint arXiv:2008.13106},
  year   = {2024}
}