English

Hasse norm principle for Heisenberg extensions of degree $p^3$

Number Theory 2025-03-20 v1 Algebraic Geometry

Abstract

Let kk be a global field and pp be an odd prime number. We give a necessary and sufficient condition for the Hasse norm principle for separable field extensions K/kK/k, i.e. the determination of the Shafarevich-Tate group Sha(T)Sha(T) of the norm one tori T=RK/k(1)(Gm)T=R^{(1)}_{K/k}(G_m) of K/kK/k, with [K:k]=p3[K:k]=p^3 or p2p^2 when the Galois group of the Galois closure of K/kK/k is the Heisenberg group Ep(p3)(Cp)2CpE_p(p^3)\simeq (C_p)^2\rtimes C_p of order p3p^3, i.e. the extraspecial group of order p3p^3 with exponent pp. As a consequence, we get the Tamagawa number τ(T)=p2\tau(T)=p^2, pp or 11 via Ono's formula τ(T)=H1(k,T^)/Sha(T)\tau(T)=|H^1(k,\widehat{T})|/|Sha(T)|.

Keywords

Cite

@article{arxiv.2503.15408,
  title  = {Hasse norm principle for Heisenberg extensions of degree $p^3$},
  author = {Akinari Hoshi and Aiichi Yamasaki},
  journal= {arXiv preprint arXiv:2503.15408},
  year   = {2025}
}

Comments

17 pages. arXiv admin note: substantial text overlap with arXiv:2503.14365; text overlap with arXiv:2404.01362