Brane instantons and fluxes in F-theory

TL;DR

This paper investigates how fluxes and instantons in F-theory influence the effective four-dimensional superpotential, analyzing fermionic zero modes, dualities, and supersymmetry breaking effects.

Contribution

It provides a detailed derivation of the fermionic effective action for D3-brane instantons with fluxes, including topological twisting and flux effects, and explores dual M5-brane interpretations.

Findings

Fermionic zero mode structure determines non-perturbative superpotential contributions.

SL(2,Z) invariance links F-theory instantons to M5-brane duals.

Inclusion of fluxes and supersymmetry breaking impacts the effective action.

Abstract

We study the combined effect of world-volume and background fluxes on Euclidean D3-brane instantons in F-theory compactifications. We derive an appropriate form of the fermionic effective action, in which the fermions are topologically twisted and the dynamical effect of fluxes, non-trivial axio-dilaton and warping is taken into account. We study the structure of fermionic zero modes, which determines the form of possible non-perturbative superpotential and F-terms in the four-dimensional effective action. Invariance under SL(2,Z) is discussed in detail, which allows for an interpretation of the results in terms of the dual M5-brane instanton in the M-theory picture. We also provide the perturbative IIB description in the orientifold limit, when available. Furthermore, we consider the possible inclusion of supersymmetry breaking bulk fluxes and discuss its implications.