1. Rademacher Expansion of a Siegel Modular Form for N=4 Counting.
- Author
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Cardoso, Gabriel Lopes, Nampuri, Suresh, and Rosselló, Martí
- Subjects
- *
MODULAR forms , *CUSP forms (Mathematics) , *CONTINUED fractions , *STRING theory , *TORSION , *COUNTING , *TORUS - Abstract
The degeneracies of 1/4 BPS states with unit torsion in heterotic string theory compactified on a six torus are given in terms of the Fourier coefficients of the reciprocal of the Igusa cusp Siegel modular form Φ 10 of weight 10. We use the symplectic symmetries of the latter to construct a fine-grained Rademacher-type expansion which expresses these BPS degeneracies as a regularized sum over residues of the poles of 1 / Φ 10 . The construction uses two distinct SL (2 , Z) subgroups of Sp (2 , Z) which encode multiplier systems, Kloosterman sums and Eichler integrals appearing therein. Additionally, it shows how the polar data are explicitly built from the Fourier coefficients of 1 / η 24 by means of a continued fraction structure. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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