Heat Kernel Methods for Multiloop Calculations in Curved Spacetime: Nonzero Spin (2507.00177v1)

Abstract: In a previous paper we have presented a general formalism for computing Feynman diagrams for scalar fields in curved spacetime at any loop order using heat kernel methods. The main technique used is the expansion of the fully off-diagonal heat kernel in Riemann normal coordinates. In this work we extend this to include fields of nonzero spin, in particular spin-$\frac{1}{2}$ fermions.