K theoretic virtual fundamental cycle of global Kuranishi chart
Dun Tang
TL;DR
The paper constructs a $K$-theoretic virtual fundamental cycle for almost complex global orbifold Kuranishi charts as an element of $K_0(|I\mathcal{M}|)$ and develops a compatible framework of orbifold $K$-theory, fake $K$-homology, and the choose-an-operator map. It defines a sector-wise, index-theoretic pairing with the inertia orbifold and shows independence from chart choices, recovering the invariants of Abouzaid23. The central mechanism uses a $K$-theoretic cap product, wrong-way maps, and a Kawasaki-index-guided push-forward to a point, ensuring that the resulting invariants agree with the established targets in symplectic Gromov–Witten theory and quantum K-theory. The approach extends naturally to virtual orbifolds and provides a robust, chart-independent description of the virtual fundamental cycle in $K$-theory, enabling applications to permutation-equivariant quantum K-theory and beyond.
Abstract
In this paper, we define the virtual fundamental cycle of a global Kuranishi chart as an element in the (analytic) orbispace K-homology of the virtual orbifold and verify that it defines the same invariants as those in \cite{Abouzaid23}.
