English

Higher pullbacks of modular forms on orthogonal groups

Number Theory 2021-06-30 v2

Abstract

We apply differential operators to modular forms on orthogonal groups O(2,)\mathrm{O}(2, \ell) to construct infinite families of modular forms on special cycles. These operators generalize the quasi-pullback. The subspaces of theta lifts are preserved; in particular, the higher pullbacks of the lift of a (lattice-index) Jacobi form ϕ\phi are theta lifts of partial development coefficients of ϕ\phi. For certain lattices of signature (2, 2) and (2, 3), for which there are interpretations as Hilbert-Siegel modular forms, we observe that the higher pullbacks coincide with differential operators introduced by Cohen and Ibukiyama.

Keywords

Cite

@article{arxiv.1910.11681,
  title  = {Higher pullbacks of modular forms on orthogonal groups},
  author = {Brandon Williams},
  journal= {arXiv preprint arXiv:1910.11681},
  year   = {2021}
}

Comments

20 pages

R2 v1 2026-06-23T11:54:52.467Z