Heterotic Dualities and Quantum Corrections in Four-Dimensional String Compactifications

by Max Wiesner (Hamburg U.)

Tuesday 20 Oct 2026, 14:00 → 15:00 Europe/Zurich

4/2-037 - TH meeting room (CERN)

In this talk, I will discuss recent progress in understanding four-dimensional theories of quantum gravity arising from heterotic string theory and F-theory, with a particular focus on the role of quantum corrections. In the first part, I will show how the study of certain degenerations of Type IIB Calabi–Yau threefold compactifications uncovers novel heterotic–Type II dualities, which in turn allow us to construct consistent non-geometric heterotic string backgrounds giving rise to four-dimensional N=2 theories of gravity.
In the second part, I will turn to F-theory compactifications on Calabi–Yau fourfolds, which give rise to four-dimensional N=1 theories of gravity. By analyzing extreme limits in the complex structure moduli space of these fourfolds, I will argue that, contrary to classical expectations, quantum corrections must become unsuppressed, thereby invalidating the classical four-dimensional N=1 supergravity effective action. This has important implications for string model building, highlighting the limitations of classical effective field theory descriptions in certain regions of the string landscape. This talk is based on joint work with Lukas Kaufmann, Jeroen Monnee, and Timo Weigand, as well as with Christian Aoufia and Giacomo Maggiorotti.