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CP invariance

  1. Aug 14, 2006 #1
    The abundance of matter and antimatter implies the laws of nature are different for particles and antiparticles. This is shown in the way more b mesons than anti-b mesons decayed into kaons and pions - the weak force does not conserve charge/parity.

    But if CP symmetry is not conserved, does this explain the arrow of time? Particle events, when reversed, would not be a mirror image of events in 'forward' time. Is there any explanation for why this is so?
  2. jcsd
  3. Aug 14, 2006 #2


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    As I understand it, the unbrokenness of the CPT theorem means that if CP symmetry is broken then so is T symmetry. Back in the day of the original discovery of the non-P-regarding kaon decays, physicists were quick to assert that the weakly implied time asymmetry (still conditioned on C breaking) would NOT suffice to explain the overall time asymmetry of the universe. I think this is because particle theory notably does not DO the time of spacetime, but only depends on an arbitrary clock parameter and that symmetry would be what is broken.
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