English

The distribution of $G$-Weyl CM fields and the Colmez conjecture

Number Theory 2019-02-25 v3 Algebraic Geometry

Abstract

Let GG be a transitive subgroup of SdS_d and EE be a CM field of degree 2d2d with a maximal totally real GG-field. If the Galois group of the Galois closure of EE is isomorphic to the wreath product of C2C_2 and GG, then we say that EE is a GG-Weyl CM field. Let N2dWeyl(X,G)N_{2d}^{\textrm{Weyl}}(X,G) count the GG-Weyl CM fields EE of degree 2d2d with discriminant dEX|d_E| \leq X and define \begin{align*} N_{2d}^{\textrm{Weyl}}(X):=\sum_{G \leq S_d}N_{2d}^{\textrm{Weyl}}(X,G). \end{align*} Further, let N2dcm(X)N_{2d}^{\textrm{cm}}(X) count the CM fields EE of degree 2d2d with discriminant dEX|d_E| \leq X. Assuming a weak form of the upper bound in Malle's conjecture which is known to be true in many cases, we build upon an approach of Kl\"uners to prove that \begin{align*} \frac{N_{2d}^{\textrm{Weyl}}(X,G)}{N_{2d}^{\textrm{cm}}(X)} = C(d, G) + O(X^{-\alpha(d,G)}) \end{align*} and \begin{align} \frac{N_{2d}^{\textrm{Weyl}}(X)}{N_{2d}^{\textrm{cm}}(X)} = 1 + O(X^{-\beta(d)}) \qquad \qquad (0.1) \end{align} for some explicit positive constants C(d,G),α(d,G)C(d,G), \alpha(d,G), and β(d)\beta(d). We then apply these distribution results to study the Colmez conjecture. Using the recently proved averaged Colmez conjecture, we deduce that the Colmez conjecture is true for GG-Weyl CM fields. Combined with (0.1), we conclude that the Colmez conjecture is true for an asymptotic density of 100% of CM fields of degree 2d2d; in other words, the Colmez conjecture is true for a random CM field.

Keywords

Cite

@article{arxiv.1708.00044,
  title  = {The distribution of $G$-Weyl CM fields and the Colmez conjecture},
  author = {Adrian Barquero-Sanchez and Riad Masri and Frank Thorne},
  journal= {arXiv preprint arXiv:1708.00044},
  year   = {2019}
}

Comments

The introduction has been reorganized and Section 3 has been expanded. 21 pages, 3 tables