AKSZ-type Topological Quantum Field Theories and Rational Homotopy Theory

We reformulate and motivate AKSZ-type topological field theories in pedestrian terms, explaining how they arise as the most general Schwartz-type topological actions subject to a simple constraint, and how they generalize Chern$-$Simons theory and other well known topological field theories, in that they are gauge theories of flat connections of higher gauge groups (infinity-Lie algebras). Their Euler$-$Lagrange equations define quasifree graded-commutative differential algebras, or equivalently $L_\infty$-algebras, the equivalent of the Lie algebra of the gauge group; we explain how integrating out auxiliary fields in physics corresponds to taking the Sullivan minimal model of this algebra, and how the correspondence between fields and gauge transformations realizes Koszul duality. Using this dictionary, we can import topological invariants and notions (e.g.$~$the rational LS-category) to apply to this class of theories.