English

Annihilation of tor\_p(G\_S^ab) for real abelian extensions

Number Theory 2021-08-09 v2

Abstract

Preprint of a paper to appear in "Communications in Advanced Mathematical Sciences". Let K be a real abelian extension of Q. Let p be a prime number, S the set of p-places of K and G\_K,S the Galois group of the maximal S-ramified pro-p-extension of K (i.e., unramified outside p and infinity). We revisit the problem of annihilation of the p-torsion group T\_K:=tor\_Z\_p(G\_K,S^ab) initiated by us and Oriat then systematized in our paper on the construction of p-adic L-functions in which we obtained a canonical ideal annihilator of T\_K in full generality (1978--1981). Afterwards (1992--2014) some annihilators, using cyclotomic units, were proposed by Solomon, Belliard--Nguyen Quang Do, Nguyen Quang Do--Nicolas, All, Belliard--Martin.In this text, we improve our original papers and show that, in general, the Solomon elements are not optimal and/or partly degenerated. We obtain, whatever K and p, an universal non-degenerated annihilator in terms of p-adic logarithms of cyclotomic numbers related to L\_p-functions at s=1 of its primitive characters of K (Theorem 9.4). Some computations are given with PARI programs; the case p=2 is analyzed and illustrated in degrees 2, 3, 4 to test a conjecture.

Keywords

Cite

@article{arxiv.1806.03137,
  title  = {Annihilation of tor\_p(G\_S^ab) for real abelian extensions},
  author = {Georges Gras},
  journal= {arXiv preprint arXiv:1806.03137},
  year   = {2021}
}

Comments

Analyse (by means of PARI programs) of the annihilations of "real classes" given by the Solomon elements and a new annihilator. Communications in Advanced Mathematical Sciences, Emrah Evren Kara, In press