On Instanton Effects in F-theory

TL;DR

This paper investigates M5-brane instanton effects on the superpotential in F-theory compactifications, analyzing zero modes, gauge structures, and one-loop determinants in specific geometries.

Contribution

It provides a detailed comparison of instanton zero modes in F-theory and its perturbative limit, developing methods for their computation and exploring geometric aspects of one-loop determinants.

Findings

Zero modes are geometrically characterized in F-theory.

Exceptional gauge group structures influence instanton effects.

Geometrical aspects of the one-loop determinant are discussed.

Abstract

We revisit the issue of M5-brane instanton corrections to the superpotential in F-theory compactifications on elliptically fibered Calabi-Yau fourfolds. Elaborating on concrete geometries, we compare the instanton zero modes for non-perturbative F-theory models with the zero modes in their perturbative Sen limit. The fermionic matter zero modes localized on the intersection of the instanton with the space-time filling D7-branes show up in a geometric way in F-theory. Methods for their computation are developed and, not surprisingly, exceptional gauge group structures do appear. Finally, quite intriguing geometrical aspects of the one-loop determinant are discussed.