This paper by Yasha Savelyev caught my eye. It appears to blend together ideas from the Segal-Stolz-Teichner approach to elliptic cohomology and Costello’s notion of topological conformal field theories.

- 4-manifold Abel Lecture algebraic K-theory axiomization calibrated geometry Cerf theory Clark Barwick cobordism hypothesis comparison problem Costello emily riehl Frobenius algebra generators and relations higher category theory homotopy category homotopy theory Mike Hopkins Morse 2-function ninja open-closed quantum field theory Stolz-Teichner symmetric monoidal bicategories topological conformal field theory topological field theories unicity Yasha Savelyev