In article <4Q5ClMhU7...@cc.usu.edu>, Charles Torre <to...@cc.usu.edu> wrote:You are right, this is a non-local Lagrangian. To let the cat out of
>In article <8j0e95$...@gap.cco.caltech.edu>, ke...@cco.caltech.edu (Kevin A. Scaldeferri) writes:
>> In article <UFS$3V8YH...@cc.usu.edu>, Charles Torre <to...@cc.usu.edu> wrote:
>>>Nah. If there is a Lagrangian formulation then there is a
>> I'm not sure this is true. I can write down a Lagrangian with an
>Well, ahem, hmmm. Okay. But you are stretching the definition of
the bag, what I am thinking of is the sort of Lagrangian encountered
in non-commutative field theories.
>I would be interested in hearing some more aboutThese cases are different from an effective action. There is not a
>cases where it is useful to think in terms of Lagrangians with an
>infinite number of derivatives. Oh. Maybe you are thinking about
>effective actions in quantum theory? Fair enough. (Still,
>even though an infinite number of derivatives may arise in a
>derivative expansion of the "Lagrangian", one usually truncates
>to a finite number of terms in any perturbative computation.
>Then what I said still applies.)
momentum expansion the way there usually is in an effective theory.
OTOH, as I said, this case is a little perverse as the theories with
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