A note on modular forms and generalized anomaly cancellation formulas 2
Siyao Liu, Yong Wang
TL;DR
The paper addresses the extension of modular anomaly cancellation formulas to $(a,b)$-type cancellations on even-dimensional manifolds and the construction of modular secondary forms via transgression on odd-dimensional manifolds. It employs characteristic forms, Jacobi theta functions, and modular form theory to build generating functions $Q_1(\\tau)$, $Q_2(\\tau)$ (and their twists with line bundles or additional bundles) and proves their modularity on subgroups $\\Gamma_{0}(2)$, $\\Gamma^{0}(2)$, and $\\Gamma_{\\theta}$, yielding concrete 4d and 8d dimensional corollaries and integrality/divisibility results. The approach centers on expressing twisted $\\widehat{A}$-genera in terms of theta-function data, deriving transformation laws, and translating these into explicit cancellation formulas that generalize previous Han-Liu-Zhang results. The transgression framework further provides modularity properties for odd-dimensional manifolds, enriching the landscape of elliptic-genus-like invariants under bundle twists with potential implications for anomaly cancellation in geometric settings.
Abstract
In [7], Liu and Wang generalized the Han-Liu-Zhang cancellation formulas to the (a, b) type cancellation formulas. In this note, we prove some another (a, b) type cancellation formulas for even-dimensional Riemannian manifolds. And by transgression, we obtain some characteristic forms with modularity properties on odd-dimensional manifolds.
