jtceleron
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This question is from K. Huang, Quantum Field Theory: from operators to path integrals.
He says that, under a continuous infinitesimal transformation,
[itex]\phi[/itex](x)->[itex]\phi[/itex](x)+[itex]\delta\phi[/itex]
the change of the Lagrangian density must be in the from
[itex]\delta[/itex]L=[itex]∂^{\mu}[/itex][itex]W_{\mu}[/itex](x)
It is easily understood that this quantity must be Lorentz-invariant, but why should only be this form, not others (e.g. without derivatives).
He says that, under a continuous infinitesimal transformation,
[itex]\phi[/itex](x)->[itex]\phi[/itex](x)+[itex]\delta\phi[/itex]
the change of the Lagrangian density must be in the from
[itex]\delta[/itex]L=[itex]∂^{\mu}[/itex][itex]W_{\mu}[/itex](x)
It is easily understood that this quantity must be Lorentz-invariant, but why should only be this form, not others (e.g. without derivatives).