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THETA BLOCK FOURIER EXPANSIONS, BORCHERDS PRODUCTS AND A SEQUENCE OF NEWMAN AND SHANKS

Part of: Abelian varieties and schemes Discontinuous groups and automorphic forms

Published online by Cambridge University Press:  14 June 2018

CRIS POOR Open the ORCID record for CRIS POOR [Opens in a new window] ,
JERRY SHURMAN Open the ORCID record for JERRY SHURMAN [Opens in a new window]  and
DAVID S. YUEN Open the ORCID record for DAVID S. YUEN [Opens in a new window]
CRIS POOR
Affiliation:
Department of Mathematics, Fordham University, Bronx, NY 10458, USA email poor@fordham.edu
JERRY SHURMAN*
Affiliation:
Department of Mathematics, Reed College, Portland, OR 97202, USA email jerry@reed.edu
DAVID S. YUEN
Affiliation:
Department of Mathematics, University of Hawaii, Honolulu, HI 96822, USA email yuen@math.hawaii.edu
*
✉jerry@reed.edu
Rights & Permissions [Opens in a new window]

Abstract

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The ‘Borcherds products everywhere’ construction [Gritsenko et al., ‘Borcherds products everywhere’, J. Number Theory148 (2015), 164–195] creates paramodular Borcherds products from certain theta blocks. We prove that the $q$-order of every such Borcherds product lies in a sequence $\{C_{\unicode[STIX]{x1D708}}\}$, depending only on the $q$-order $\unicode[STIX]{x1D708}$ of the theta block. Similarly, the $q$-order of the leading Fourier–Jacobi coefficient of every such Borcherds product lies in a sequence $\{A_{\unicode[STIX]{x1D708}}\}$, and this is the sequence $\{a_{n}\}$ from work of Newman and Shanks in connection with a family of series for $\unicode[STIX]{x1D70B}$. Our proofs use a combinatorial formula giving the Fourier expansion of any theta block in terms of its germ.

Keywords

paramodular formBorcherds producttheta blockJacobi form

MSC classification

Primary: 11F46: Siegel modular groups; Siegel and Hilbert-Siegel modular and automorphic forms
Secondary: 11F55: Other groups and their modular and automorphic forms (several variables) 11F30: Fourier coefficients of automorphic forms 11F50: Jacobi forms 14K25: Theta functions
Type
Research Article
Information
Bulletin of the Australian Mathematical Society , Volume 98 , Issue 1 , August 2018 , pp. 48 - 59
Copyright
© 2018 Australian Mathematical Publishing Association Inc. 

References

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