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arXiv · 2504.19125

Eisenstein cocycles for imaginary quadratic fields

Emmanuel Lecouturier·Romyar Sharifi·Sheng-Chi Shih·Jun Wang
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Abstract

We construct Eisenstein cocycles for arithmetic subgroups of GL_2 of imaginary quadratic fields valued in second K-groups of products of two CM elliptic curves. We use these to construct maps from the first homology groups of Bianchi spaces to corresponding second K-groups of ray class fields and to verify the Eisenstein property of these maps for prime-to-level Hecke operators.

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Emmanuel Lecouturier, Romyar Sharifi, Sheng-Chi Shih, Jun Wang. 2025-04-27. Eisenstein cocycles for imaginary quadratic fields. https://arxiv.org/abs/2504.19125

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