Abstract

In this talk, we identify a Zs discrete gravitational theta angle in the non-supersymmetricSO(16) x SO(16) heterotic string, which is detected by a 10D spacetime manifold that is anSp(2) group manifold. In the first part, we explain the string theory computation that identifies thisZ, theta angle, involving non-perturbative anomaly on the instantonic NS5 branes. in the secondpart, we motivate our endeavor by Stolz-Teichner conjecture which relates 2D(0, 1) SQFT toTopological modular forms. Our result identifies two generators of torsional classes in TMF ofspecific degrees by explicit 2D(0,1) theories: one begins a 2D(0,1) sigma model to Sp(2), theother being the SO(16)xSO(16) chiral fermionic SCFT. Based on 2403.08861 with YujiTachikawa.