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Peskin 3.82

  1. Apr 24, 2010 #1
    peskin`s introduction to QFT [3.82],do not know what he had done to the underline

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  2. jcsd
  3. Apr 24, 2010 #2
    write out the components of each entry in the matrices
  4. Apr 24, 2010 #3
    i see ,but why the \singma[\nu]\sigma[\lambta] in the first row can be write to that in the second row,:confused:
  5. Apr 24, 2010 #4
    what properties of the sigma can u think of?
  6. Apr 24, 2010 #5
    many thanks .it is my fault,i don`t express my question clearly,so
    sigma is the 2*2 pauli matrix ,but subscript of the front two sigma matrixs in the first row is \beta ,in the second it changes to \delta,that is what i puzzled.
  7. Apr 24, 2010 #6
    just write out every dirac index and massage it
  8. Apr 24, 2010 #7
    :smile: get it ,there is a change which is important and very simple ,and it is until now that i realized it :
    thanks a lot!
  9. Apr 25, 2010 #8
    ah great, I was about to do this all for myself so that I could pin-point exactly what is going on ;)

    It "always" work to write out the Dirac indices

    One thing I dont like is that Peskin uses greek letter for Dirac index sometimes.. like here, very annoying and confusing
  10. May 7, 2012 #9
    For posterity, here's a step-by-step derivation of line 1 to line 2 of eqn. 3.82 for Peskin & Schroeder QFT.

    Attached Files:

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