Imagine you’re trying to learn quantum field theory, and you just got to a tricky part: deriving the LSZ reduction formula (don’t worry, you don’t have to know what this is!). The calculation and algebra are a little messy, particularly if you’re working with the fermionic case. When going through the derivation, it’s easy to lose the forest for the trees. In these cases, I find it helpful to ask, “What’s the story here?†This…
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