Title: The Large Scale Structure of α′ Effects in String Theory

Abstract:

In this talk, I present preliminary results of a project on completing the ten-dimensional type II effective actions at higher order in string perturbation theory. I focus mostly on type IIB superstring theory by investigating the structure of higher derivative couplings in the RR-sector. I present concrete evidence at the level of five-point superstring amplitudes that the kinematics in the maximally U(1)-violating sector is obtained from standard superspace integrals over sixteen fermionic coordinates. This is in line with 11D superparticle amplitudes in M-theory compactified on 2-tori where the well-known modular forms required for SL(2,Z) invariance of the type IIB theory arise from integrating out winding modes on the torus. If there is enough time, I briefly talk about the systematics of α’ corrections in F-theory compactifications to 4 dimensions on Calabi-Yau fourfolds.