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arXiv · 2107.01992

Eisenstein cohomology classes for $\mathrm{GL}_N$ over imaginary quadratic fields

Nicolas Bergeron·Pierre Charollois·Luis E. Garcia
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Abstract

We study the arithmetic of degree $N-1$ Eisenstein cohomology classes for locally symmetric spaces associated to $\mathrm{GL}_N$ over an imaginary quadratic field $k$. Under natural conditions we evaluate these classes on $(N-1)$-cycles associated to degree $N$ extensions $F/k$ as linear combinations of generalised Dedekind sums. As a consequence we prove a remarkable conjecture of Sczech and Colmez expressing critical values of $L$-functions attached to Hecke characters of $F$ as polynomials in Kronecker--Eisenstein series evaluated at torsion points on elliptic curves with multiplication by $k$. We recover in particular the algebraicity of these critical values.

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BibTeXRIS

Nicolas Bergeron, Pierre Charollois, Luis E. Garcia. 2021-07-05. Eisenstein cohomology classes for $\mathrm{GL}_N$ over imaginary quadratic fields. https://arxiv.org/abs/2107.01992

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