For questions about gauge theory in mathematical physics and differential geometry. Typical questions pertain to bundles, connections, spinors, and moduli spaces. Questions about the physics of gauge fields should be directed to physics.stackexchange.
Gauge theory is a branch of mathematical physics, differential geometry, and differential topology. The aim is to study the geometry and topology of a space by examining an appropriate moduli space of connections (and possibly spinors) which satisfy certain PDE. These PDE frequently have their origins in physics.
Topics of gauge theory include connections on principal bundles, gauge groups, Yang-Mills connections, (anti-)self-dual connections, stability of vector bundles, Donaldson invariants, the Seiberg-Witten equations and invariants, the Bogomolnyi (monopole) equation, Chern-Simons invariant, Donaldson-Thomas theory, relations to Gromov-Witten theory, applications to low-dimensional topology.