English

Quasiplatonic curves with symmetry group ${\mathbb Z}_{2}^{2} \rtimes {\mathbb Z}_{m}$ are definable over ${\mathbb Q}$

Algebraic Geometry 2017-12-11 v3

Abstract

It is well known that every closed Riemann surface SS of genus g2g \geq 2, admitting a group GG of conformal automorphisms so that S/GS/G has triangular signature, can be defined over a finite extension of Q{\mathbb Q}. It is interesting to know, in terms of the algebraic structure of GG, if SS can in fact be defined over Q{\mathbb Q}. This is the situation if GG is either abelian or isomorphic to AZ2A \rtimes {\mathbb Z}_{2}, where AA is an abelian group. On the other hand, as shown by Streit and Wolfart, if G=ZpZqG = {\mathbb Z}_{p} \rtimes {\mathbb Z}_{q} where p,q>3p,q>3 are prime integers, then SS is not necessarily definable over Q{\mathbb Q}. In this paper, we observe that if G=Z22ZmG={\mathbb Z}_{2}^{2} \rtimes {\mathbb Z}_{m} with m3m \geq 3, then SS can be defined over Q{\mathbb Q}. Moreover, we describe explicit models for SS, the corresponding groups of automorphisms and an isogenous decomposition of their Jacobian varieties as product of Jacobians of hyperelliptic Riemann surfaces.

Keywords

Cite

@article{arxiv.1604.00702,
  title  = {Quasiplatonic curves with symmetry group ${\mathbb Z}_{2}^{2} \rtimes {\mathbb Z}_{m}$ are definable over ${\mathbb Q}$},
  author = {Rubén A. Hidalgo and Leslie Jiménez and Saúl Quispe and Sebastián Reyes-Carocca},
  journal= {arXiv preprint arXiv:1604.00702},
  year   = {2017}
}