Differential Models for Anderson Dual to Twisted $\mathrm{Spin}^c$-Bordism and Twisted Anomaly Map
Fei Han, Yuanchu Li
TL;DR
The paper develops differential refinements of twisted $ ext{Spin}^c$-bordism and its Anderson dual, constructing two parallel, equivalent models: a differential extension built from twisted de Rham complexes and currents, and a gerbe-theoretic framework using bundle gerbe modules to encode twists and Dirac-operator data. It then defines a differential twisted anomaly map from $igl( ext{K}^{0}(X, au^{-1})igr)$ to the twisted Anderson dual, realized via the twisted Chern character and reduced eta-invariants in the presence of a differential twist $ au$. The work extends Yamashita–Yonekura’s de Rham models to the twisted setting and proves the equivalence of the differential extensions, including a differential multiplication and pushforward, along with an explicit geometric realization via gerbes. The resulting twisted anomaly map provides a geometric bridge between differential twisted $K$-theory and invertible field theories, aligning with the Stolz–Teichner program and enabling index-theoretic computations for twisted 1|1-dimensional supersymmetric theories.
Abstract
We construct differential models for twisted $\mathrm{Spin}^c$-bordism and for its Anderson dual, and employ the latter to define a twisted anomaly map whose source is the differential twisted $K$-theory. Our differential model for the twisted Anderson dual follows the formalism developed in [YY23]. To connect these constructions with the geometric framework of the Atiyah-Singer index theory, we further present a gerbe-theoretic formulation of our models in terms of bundle gerbes and gerbe modules [Mur96] [BCMMS02]. Within this geometric setting, we define the twisted anomaly map \[ \widehatΦ_{\widehat{\mathcal{G}}}\colon \widehat{K}^{0}(X,\widehat{\mathcal{G}}^{-1}) \longrightarrow \bigl(\widehat{IΩ^{\mathrm{Spin}^c}_{\mathrm{dR}}}\bigr)^{n}(X,\widehat{\mathcal{G}}), \] whose construction naturally involves the reduced eta-invariant of Dirac operators acting on Clifford modules determined by the twisted data. Conceptually, this map is expected to encode the anomalies of twisted $1|1$-dimensional supersymmetric field theories, in accordance with the perspectives developed in [ST11] and [FH21].
