Symmetry, Integrability and Geometry: Methods and Applications SIGMA 17 (2021), 018, 24 pages Quantum K-Theory of Grassmannians and Non-Abelian Localization Alexander GIVENTAL and Xiaohan YAN Department of Mathematics, University of California at Berkeley, Berkeley, CA 94720, USA E-mail:
[email protected], xiaohan
[email protected] Received August 25, 2020, in final form February 02, 2021; Published online February 26, 2021 https://doi.org/10.3842/SIGMA.2021.018 Abstract. In the example of complex grassmannians, we demonstrate various techniques available for computing genus-0 K-theoretic GW-invariants of flag manifolds and more gene- ral quiver varieties. In particular, we address explicit reconstruction of all such invariants using finite-difference operators, the role of the q-hypergeometric series arising in the context of quasimap compactifications of spaces of rational curves in such varieties, the theory of twisted GW-invariants including level structures, as well as the Jackson-type integrals playing the role of equivariant K-theoretic mirrors. Key words: Gromov{Witten invariants; K-theory; grassmannians; non-abelian localization 2020 Mathematics Subject Classification: 14N35 To Vitaly Tarasov and Alexander Varchenko, on their anniversaries 1 Introduction Just as quantum cohomology theory deals with intersection numbers between interesting cyc- les in moduli spaces of stable maps of holomorphic curves in a given target (say, a K¨ahler manifold), quantum K-theory studies sheaf cohomology (e.g., in the form of holomorphic Euler characteristics) of interesting vector bundles over these moduli spaces. The beginnings of the subject can be traced back to the 20-year-old note [9] by the first-named author, the foundational work by Y.-P.