3
votes
1answer
111 views

Definition of Local Function

Now a days I am studying Srednicki's QFT book. In its third chapter it is written that Any local function of φ(x) is a Lorentz scalar, [...] . Now my question is: What is a local function?
13
votes
3answers
2k views

Why are higher order Lagrangians called 'non-local'?

And in what sense are they 'non-local'?