English

A short remark on the $\ell$-torsion part of class groups

Number Theory 2026-03-10 v1

Abstract

In a 2008 paper Ellenberg suggested a strategy to improve the known upper bounds for the \ell-torsion part of class groups of number fields of fixed degree dd. Motivated by this he proposed a question about the number of primitive elements of small height in a number field. Here we answer Ellenberg's question. We also improve Heath-Brown's bound for the \ell-torsion part of class groups of purely cubic number fields, and we generalize our improvement to pure fields of arbitrary odd degree dd.

Keywords

Cite

@article{arxiv.2603.08121,
  title  = {A short remark on the $\ell$-torsion part of class groups},
  author = {Martin Widmer},
  journal= {arXiv preprint arXiv:2603.08121},
  year   = {2026}
}