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About Noether's theorem

  1. Mar 12, 2013 #1
    This question is from K. Huang, Quantum Field Theory: from operators to path integrals.

    He says that, under a continuous infinitesimal transformation,
    the change of the Lagrangian density must be in the from

    It is easily understood that this quantity must be Lorentz-invariant, but why should only be this form, not others (e.g. without derivatives).
  2. jcsd
  3. Mar 12, 2013 #2
    because only in this way,it can not affect the action integral.It is 4 divergence,so it will vanish.
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