On α′ corrections in N=1 F-theory compactifications

We consider N=1 F-theory and Type IIB orientifold compactifications and derive new α′ corrections to the four-dimensional effective action. They originate from higher derivative corrections to eleven-dimensional supergravity and survive the M-theory to F-theory limit. We find a correction to the Kähler potential depending on the volume of a non-trivial intersection curve of seven-branes. At weak string coupling this correction arises from the intersection of D7-branes with the O7-plane. We also analyze a four-dimensional higher curvature correction.