English

Zagier's weight $3/2$ mock modular form

Number Theory 2022-05-19 v2

Abstract

Mock modular forms have their origins in Ramanujan's pioneering work on mock theta functions. In a 1975 paper, Zagier proved certain transformation properties of the generating function of the Hurwitz class numbers H(n)H(n) for the discriminant (n)(-n). In the modern framework, these results show that the generating function of H(n)H(n) is a mock modular form of weight 3/2 with the theta function being the shadow. In this expository paper, we provide a detailed proof of Zagier's result.

Keywords

Cite

@article{arxiv.2012.00539,
  title  = {Zagier's weight $3/2$ mock modular form},
  author = {Ajit Bhand and Ranveer Kumar Singh},
  journal= {arXiv preprint arXiv:2012.00539},
  year   = {2022}
}

Comments

A new lemma has been added, proofs of some of the lemmas have been corrected

R2 v1 2026-06-23T20:38:29.291Z