Instantons are an important source of non-perturbative effects in gauge theories. With enough supersymmetry, these effects can be exactly calculated using the technique of equivariant localization. Such calculations have led to the discovery of rich connections to quantum integrable systems and two dimensional conformal field theories.
The setup of spiked instantons is a far-reaching generalisation of ordinary instantons introduced by Nekrasov in the context of the BPS/CFT correspondence. They provide a unified way to understand the various exact non-perturbative effects alluded to above. In this seminar, we shall look at a description of the spiked instanton moduli space from a string theory viewpoint where it is realized as the moduli space of bound states of intersecting D-branes. Some interesting issues regarding tachyon condensation shall be encountered along the way.