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A What is CPT a symmetry of?

  1. Mar 28, 2016 #1
    I was looking at the wikipedia article on CPT and it starts with "Charge, Parity, and Time Reversal Symmetry is a fundamental symmetry of physical laws under the simultaneous transformations of charge conjugation (C), parity transformation (P), and time reversal (T)."

    What does it mean that CPT is a symmetry of the "physical laws?" Is it obvious that a QFT has CPT symmetry from its Lagrangian? For example, if I had a Lagrangian for some QFT, and replaced the particle fields with anitparticle fields and vise versa, does C symmetry imply that the two conjugate Lagrangians will yield the same equations of motion? If so, how could a parity or time inversion operation be applied to a Lagrangian in the same way?

    What is the precise meaning of "physical laws?"
  2. jcsd
  3. Mar 29, 2016 #2


    Staff: Mentor

    Here's the wikipedia article on it:


  4. Mar 29, 2016 #3

    A. Neumaier

    User Avatar
    Science Advisor

    In this context, it means the Wightman axioms for quantum field theory, from which CPT symmetry is derivable with full rigor.
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