English

Constructing Certain Special Analytic Galois Extensions

Number Theory 2020-09-24 v2

Abstract

For every prime p5p\geq 5 for which a certain condition on the class group Cl(Q(μp))\text{Cl}(\mathbb{Q}(\mu_p)) is satisfied, we construct a pp-adic analytic Galois extension of the infinite cyclotomic extension Q(μp)\mathbb{Q}(\mu_{p^{\infty}}) with some special ramification properties. In greater detail, this extension is unramified at primes above pp and tamely ramified above finitely many rational primes and is isomorphic to a finite index subgroup of SL2(Zp)\text{SL}_2(\mathbb{Z}_p) which contains the principal congruence subgroup. For the primes 107,139,271107,139,271 and 379379 such extensions were first constructed by Ohtani and Blondeau. The strategy for producing these special extensions at an abundant number of primes is through lifting two-dimensional reducible Galois representations which are diagonal when restricted to pp.

Keywords

Cite

@article{arxiv.1812.02797,
  title  = {Constructing Certain Special Analytic Galois Extensions},
  author = {Anwesh Ray},
  journal= {arXiv preprint arXiv:1812.02797},
  year   = {2020}
}

Comments

5 pages, submitted version

R2 v1 2026-06-23T06:34:48.668Z