Invertible QFTs and differential Anderson duals

This is the proceeding of a talk given at Stringmath 2022. We introduce a Cheeger-Simons type model for the differential extension of Anderson dual to generalized homology theory with physical interpretations. This construction generalizes the construction of the differential Anderson dual to bordism homology theories, given in a previous work of Yonekura and the author.Comment: 18 page

ALGEBRAIC TOPOLOGY AND PHYSICS (Women in Mathematics)

Recently, there has been a growing interest in the relations between algebraic topology and physics. Algebraic topology is used to classify physical systems, and it can be a very powerful tool to analyze physical problems in purely mathematical ways. In this talk, I explain this idea and some of my related works

Topological modular forms and the absence of all heterotic global anomalies

We reformulate the question of the absence of global anomalies of heterotic string theory mathematically in terms of a certain natural transformation $\mathrm{TMF}^\bullet\to (I_{\mathbb{Z}}\Omega^\text{string})^{\bullet-20}$, from topological modular forms to the Anderson dual of string bordism groups, using the Segal-Stolz-Teichner conjecture. We will show that this natural transformation vanishes, implying that heterotic global anomalies are always absent. The fact that $\mathrm{TMF}^{21}(\mathrm{pt})=0$ plays an important role in the process. Along the way, we also discuss how the twists of $\mathrm{TMF}$ can be described under the Segal-Stolz-Teichner conjecture, by using the result of Freed and Hopkins concerning anomalies of quantum field theories. The paper contains separate introductions for mathematicians and for string theorists, in the hope of making the content more accessible to a larger audience. The sections are also demarcated cleanly into mathematically rigorous parts and those which are not.Comment: 36 pages; v2: incorporates many suggestions by a helpful anonymous refere

Remarks on mod-2 elliptic genus

For physicists: For supersymmetric quantum mechanics, there are cases when a mod-2 Witten index can be defined, even when a more ordinary $\mathbb{Z}$-valued Witten index vanishes. Similarly, for 2d supersymmetric quantum field theories, there are cases when a mod-2 elliptic genus can be defined, even when a more ordinary elliptic genus vanishes. We study such mod-2 elliptic genera in the context of $\mathcal{N}=(0,1)$ supersymmetry, and show that they are characterized by mod-2 reductions of integral modular forms, under some assumptions. For mathematicians: We study the image of the standard homomorphism $\pi_n \mathrm{TMF}\to \pi_n \mathrm{KO}((q))\simeq \mathbb{Z}/2((q))$ for $n=8k+1$ or $8k+2$, by relating them to the mod-2 reductions of integral modular forms.Comment: 31 page

Spectral convergence in geometric quantization --- the case of non-singular Langrangian fibrations

We develop a new approach to geometric quantization using the theory of convergence of metric measure spaces. Given a family of K\"ahler polarizations converging to a non-singular real polarization on a prequantized symplectic manifold, we show the spectral convergence result of $\bar{\partial}$-Laplacians, as well as the convergence result of quantum Hilbert spaces. We also consider the case of almost K\"ahler quantization for compatible almost complex structures, and show the analogous convergence results