{ "id": "1808.00029", "version": "v1", "published": "2018-07-31T19:02:45.000Z", "updated": "2018-07-31T19:02:45.000Z", "title": "On 5-torsion of CM elliptic curves", "authors": [ "Laura Paladino" ], "categories": [ "math.NT" ], "abstract": "Let $\\mathcal{E}$ be an elliptic curve defined over a number field $K$. Let $m$ be a positive integer. We denote by ${\\mathcal{E}}[m]$ the $m$-torsion subgroup of $\\mathcal{E}$ and by $K_m:=K({\\mathcal{E}}[m])$ the number field obtained by adding to $K$ the coordinates of the points of ${\\mathcal{E}}[m]$. We describe the fields $K_5$, when $\\mathcal{E}$ is a CM elliptic curve defined over $K$, with Weiestrass form either $y^2=x^3+bx$ or $y^2=x^3+c$. In particular we classify the fields $K_5$ in terms of generators, degrees and Galois groups. Furthermore we show some applications of those results to the Local-Global Divisibility Problem, to modular curves and to Shimura curves.", "revisions": [ { "version": "v1", "updated": "2018-07-31T19:02:45.000Z" } ], "analyses": { "keywords": [ "cm elliptic curve", "number field", "local-global divisibility problem", "shimura curves", "torsion subgroup" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }