An explicit formula is derived for the generating function of vertical D4–D2–D0 bound states on smooth K3 fibered Calabi–Yau threefolds, generalizing previous results of Gholampour and Sheshmani. It is also shown that this formula satisfies strong modularity properties, as predicted by string theory. This leads to a new construction of vector valued modular forms which exhibit some of the features of a generalized Hecke transform.
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Mathematical Physics