Shell formulas for instantons and gauge origami

Abstract: We introduce the shell formula -- a framework capable of providing a unified description for various partition functions whose pole structures are classified by Young diagrams of arbitrary dimension. This formalism encompasses a wide range of physical systems, including instanton partition functions of 5d pure super Yang-Mills theory with classical gauge groups, as well as gauge origami configurations such as the magnificent four, tetrahedron instantons, Donaldson-Thomas invariants, and spiked instantons.