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This paper has three main objectives: (i) To establish an isomorphism between Jacobi forms of index $D_{2n+1}$ (lattice index) and elliptic modular forms of level $2$. (ii) To provide an explicit formula for the Fourier coefficients of…

Number Theory · Mathematics 2026-04-01 Shuichi Hayashida

In 1975, Cohen constructed a kind of one-variable modular forms of half-integral weight, says $r+(1/2),$ whose $n$-th Fourier coefficient $H(n)$ only occurs when $(-1)^r n$ is congruent to 0 or 1 modulo 4. The space of modular forms whose…

Number Theory · Mathematics 2015-09-21 Ren He Su

We consider the Kudla-Millson theta series associated to a quadratic space of signature $(N,N)$. By combining a `see-saw' argument with the Siegel-Weil formula, we show that its (regularized) integral along a torus attached to a totally…

Number Theory · Mathematics 2022-11-22 Romain Branchereau

By adapting the work of Kudla and Millson we obtain a lifting of cuspidal cohomology classes for the symmetric space associated to GO(V) for an indefinite rational quadratic space V of even dimension to holomorphic Siegel modular forms on…

Number Theory · Mathematics 2009-02-27 Tobias Berger

In this paper, we construct Shintani lifts from integral weight weakly holomorphic modular forms to half-integral weight weakly holomorphic modular forms. Although defined by different methods, these coincide with the classical Shintani…

Number Theory · Mathematics 2014-05-20 Kathrin Bringmann , Pavel Guerzhoy , Ben Kane

Recently, Mertens, Ono, and the third author studied mock modular analogues of Eisenstein series. Their coefficients are given by small divisor functions, and have shadows given by classical Shimura theta functions. Here, we construct a…

Number Theory · Mathematics 2024-07-24 Joshua Males , Andreas Mono , Larry Rolen

We introduce an alternate set of generators for the Hecka algebra, and give an explicit formula for the action of these operators on Fourier coefficients. With this, we compute the eigenvalues of Hecke operators acting on average Siegel…

Number Theory · Mathematics 2011-10-31 Lynne H. Walling

We compute the Fourier expansion of vector valued Eisenstein series for the Weil representation associated to an even lattice. To this end, we define certain twists by Dirichlet characters of the usual Eisenstein series associated to…

Number Theory · Mathematics 2020-06-19 Markus Schwagenscheidt

We define canonical real analytic versions of modular forms of integral weight for the full modular group, generalising real analytic Eisenstein series. They are harmonic Maass waveforms with poles at the cusp, whose Fourier coefficients…

Number Theory · Mathematics 2017-11-07 Francis Brown

We find explicit change-of-basis formulas between Eisenstein series attached to cusps, and newform Eisenstein series attached to pairs of primitive Dirichlet characters. As a consequence, we prove a Bruggeman-Kuznetsov formula for newforms…

Number Theory · Mathematics 2020-08-17 Matthew P Young

For a class of generalized holomorphic Eisenstein series, we establish complete asymptotic expansions (Theorems~1~and~2), which together with the explicit expression of the latter remainder (Theorem~3), naturally transfer to several new…

Number Theory · Mathematics 2023-04-12 Masanori Katsurada , Takumi Noda

The goal of this paper is to construct the p-adic analytic family of overconvergent half-integral weight modular forms using Hecke-equivariant overconvergent Shintani lifting. The classical Shintani map is the Hecke-equivariant map from the…

Number Theory · Mathematics 2007-05-23 Jeehoon Park

The purpose of this article is to give a simple and explicit construction of mock modular forms whose shadows are Eisenstein series of arbitrary integral weight, level, and character. As application, we construct forms whose shadows are…

Number Theory · Mathematics 2018-09-18 Sebastián Herrero , Anna-Maria von Pippich

We show that the meromorphic modular forms recently considered by Bringmann and Kane can be obtained as images of regularized theta lifts of Poincar\'{e} series under weight raising operators. We use this fact in order to simplify the…

Number Theory · Mathematics 2020-08-13 Shaul Zemel

We give a list of $113$ holomorphic eta-quotients of integral weight ($66$ of which are primitive) and provide a uniform closed formula for their Fourier coefficients $c(l)$ where $l\equiv1\bmod{m}$ with some fixed $m\mid24$. The proof…

Number Theory · Mathematics 2025-09-11 Xiao-Jie Zhu

We consider certain double series of Eisenstein type involving hyperbolic-sine functions. We define certain generalized Hurwitz numbers, in terms of which we evaluate those double series. Our main results can be regarded as a certain…

Number Theory · Mathematics 2016-04-29 Yasushi Komori , Kohji Matsumoto , Hirofumi Tsumura

This is the third part of a series of articles providing a foundation for the theory of Drinfeld modular forms of arbitrary rank. In the present article we construct and study some examples of Drinfeld modular forms. In particular we define…

Number Theory · Mathematics 2018-06-01 Dirk Basson , Florian Breuer , Richard Pink

By the theory of Eisenstein series, generating functions of various divisor functions arise as modular forms. It is natural to ask whether further divisor functions arise systematically in the theory of mock modular forms. We establish,…

Number Theory · Mathematics 2020-09-30 Michael H. Mertens , Ken Ono , Larry Rolen

We study nearly holomorphic Siegel Eisenstein series of general levels and characters on $\mathbb{H}_{2n}$, the Siegel upper half space of degree $2n$. We prove that the Fourier coefficients of these Eisenstein series (once suitably…

Number Theory · Mathematics 2021-09-21 Ameya Pitale , Abhishek Saha , Ralf Schmidt

We study an Eisenstein series of weight $20/9$, level $11$ whose multiplier system is the same as $\eta^{44/9}(\tau)\eta^{-4/9}(11\tau)$. We prove that it is a modular form and obtain its Fourier expansion.

Number Theory · Mathematics 2023-04-18 Xiao-Jie Zhu