Dr. Engelhardt's research in theoretical physics is focused on the low-energy sector of Quantum Chromodynamics (QCD), the gauge field theory which describes the strong interaction. At low energies, the strong interaction is characterized by a number of phenomena which can only be analyzed using non-perturbative methods. Most prominent among these are the confinement of quarks and gluons into hadrons, the spontaneous breaking of chiral symmetry, and the axial U(1) anomaly which arises due to topological properties of the gauge field.