〈 Berger | Dillon 〉

how does that differ from regular phase space integration? Having said that, you usually just have to do the integrals yourself since there's a lot of δ functions and step functions.. However doing the Dirac algebra and operator simplification is easy with FeynCalc in MM

We used to do them with some program by integrating over a hypercube but I haven’t kept up with the numerical work

Interesting .. like doing the wick rotation and then just the 4D integral numerically? Wouldn't the Hypercube be infinite?

It depends but typically it’s Monte Carlo and you parameterize the phase space by choosing a mapping from the hypercube