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Hybrid subconvexity for class group 𝐿-functions and uniform sup norm bounds of Eisenstein series

  • Asbjørn Christian Nordentoft EMAIL logo
Published/Copyright: November 4, 2020

Abstract

In this paper, we study hybrid subconvexity bounds for class group L-functions associated to quadratic extensions K/ (real or imaginary). Our proof relies on relating the class group L-functions to Eisenstein series evaluated at Heegner points using formulas due to Hecke. The main technical contribution is the uniform sup norm bound for Eisenstein series E(z,1/2+it)εy1/2(|t|+1)1/3+ε, y1, extending work of Blomer and Titchmarsh. Finally, we propose a uniform version of the sup norm conjecture for Eisenstein series.

MSC 2010: 11F03; 11L07

Communicated by Jan Bruinier


Acknowledgements

I would like to express my gratitude to my advisor Morten Risager for suggesting this problem to me and for pointing me to [3] and [24], and to the referee for many useful comments, which enabled me to prove a stronger result.

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Received: 2019-07-05
Revised: 2020-07-03
Published Online: 2020-11-04
Published in Print: 2021-01-01

© 2020 Walter de Gruyter GmbH, Berlin/Boston

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