Bounds for moments of ℓ-torsion in class groups

Peter Koymans, Jesse Thorner

Research output: Contribution to journalArticlepeer-review


Fix a number field k, integers ℓ,n≥2, and a prime p. For all r≥1, we prove strong unconditional upper bounds on the rth moment of ℓ-torsion in the ideal class groups of degree p extensions of k and of degree nSn-extensions of k, improving upon results of Ellenberg, Pierce and Wood as well as GRH-conditional results of Frei and Widmer. For large r, our results are comparable with work of Heath-Brown and Pierce for imaginary quadratic extensions of Q. When r=1, our results are new even for the family of all quadratic extensions of Q, leading to an improved upper bound for the count of degree pDp-extensions over Q (where Dp is the dihedral group of order 2p).

Original languageEnglish (US)
JournalMathematische Annalen
StateAccepted/In press - 2024

ASJC Scopus subject areas

  • General Mathematics


Dive into the research topics of 'Bounds for moments of ℓ-torsion in class groups'. Together they form a unique fingerprint.

Cite this