False and partial Eisenstein series related to unimodal sequences

Fuente: arXiv
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Autores principales: Bringmann, Kathrin, Pandey, Badri Vishal, van Ittersum, Jan-Willem
Formato: Preprint
Publicado: 2026
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author Bringmann, Kathrin
Pandey, Badri Vishal
van Ittersum, Jan-Willem
author_facet Bringmann, Kathrin
Pandey, Badri Vishal
van Ittersum, Jan-Willem
contents Motivated by the fact that the classical Jacobi theta function $\vartheta$ is the exponential generating function of the Eisenstein series, we study the exponential Taylor coefficients (in the elliptic variable) of a related natural partial theta function, as well as a false theta function related to the Dedekind eta function. We prove that the space spanned by these objects is closed under differentiation, analogous to the space of quasimodular forms, and that it contains the quasimodular forms themselves. We further provide their Fourier expansions, establish quasimodular completions, and derive a recursive formula for the Taylor coefficients of the logarithm of the unimodal rank generating function, expressed as partition traces of the false and partial objects.
format Preprint
id arxiv_https___arxiv_org_abs_2601_19441
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle False and partial Eisenstein series related to unimodal sequences
Bringmann, Kathrin
Pandey, Badri Vishal
van Ittersum, Jan-Willem
Number Theory
Combinatorics
11F03, 11F11, 11F37, 11F50, 11P82
Motivated by the fact that the classical Jacobi theta function $\vartheta$ is the exponential generating function of the Eisenstein series, we study the exponential Taylor coefficients (in the elliptic variable) of a related natural partial theta function, as well as a false theta function related to the Dedekind eta function. We prove that the space spanned by these objects is closed under differentiation, analogous to the space of quasimodular forms, and that it contains the quasimodular forms themselves. We further provide their Fourier expansions, establish quasimodular completions, and derive a recursive formula for the Taylor coefficients of the logarithm of the unimodal rank generating function, expressed as partition traces of the false and partial objects.
title False and partial Eisenstein series related to unimodal sequences
topic Number Theory
Combinatorics
11F03, 11F11, 11F37, 11F50, 11P82
url https://arxiv.org/abs/2601.19441