String instantons and effective field theory
Most 4d string vacua constructions in previous chapters have been carried out in the realm of perturbation theory (around the corresponding weak coupling limit). However, there are several instances in which non-perturbative effects play an important role. In this chapter we introduce brane instantons in 4d string vacua, analyze their impact on the low-energy effective action, and discuss some applications for particle physics model building.
13.1 Instantons in field theory and string theory
Non-perturbative effects are a crucial ingredient in quantum field theory and string theory. An important class of non-perturbative effects can be described in terms of instantons, i.e. semiclassical configurations ...