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Homework Help: Peskin Eq 11.72, mathematical identity

  1. Feb 7, 2010 #1


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    In Eq 11.72 in the QFT text by Peskin, the following equality is stated:


    This suggests that


    However, I can't see how this identity follows. Differentiating the right hand side gives


    Any help would be greatly appreciated.
  2. jcsd
  3. Feb 7, 2010 #2


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    [tex]\partial_\alpha x^\alpha = \partial_\alpha e^{\alpha \log x} = e^{\alpha \log x} \log x= x^\alpha \log x[/tex]
  4. Feb 7, 2010 #3


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