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CPT Symmetry

  1. Jun 1, 2008 #1
    Is weak interaction invaraint under CPT Symmetry? Why?
  2. jcsd
  3. Jun 1, 2008 #2


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    yes it is. it is a theorem that all quantum field theories that satisfy relatively weak conditions (locality, unitarity, S-matrix,...) are CPT-invariant. weak interactions are no exception. you can prove it by referring to that theorem, or by just brute-force transforming the action under CPT and seeing that it's invariant.
  4. Jun 2, 2008 #3
    would you please expline further? How can I prove that?
  5. Jun 2, 2008 #4


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    Proof of the CPT theorem is nontrivial and requires quite a bit of background. But it is a deep and important mathematical truism about quantum field theories.

    There are various books that treat it in varying degrees of rigor. I think Weinberg proves it in his volumes, and for a more mathematical treatment see Streeter/Wightman.

    Incidentally people look for violation of the CPT experimentally, so far without success. But it would be a big deal if one day such a fundamental symmetry was broken. It would mean probably that we would need to go back to Constructive field theories for insight.
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