Stringent Tests of CPT Invariance

 

What is CPT Invariance?

C = charge conjugation (changing a particle into its antiparticle)
P = party transformation (r → -r)
T = time reversal transformation (motion reversal)

CPT is the application of all of these symmetry operations.

CPT Theorem

The CPT theorem, one of the most basic assertions of physics, arises from the success of quantum field theories. Quantum field theories seem to provide a very successful description of all interactions except for gravitational interactions. Where a quantum field theory is a correct description, along with the usual assumptions such as invariance under Lorentz transformations, the necessary result is that the reality that is described is invariant under a CPT transformation. This is called the CPT theorem. However, since gravity has not yet been successfully described by a quantum field theory, it is possible that the CPT is not universal. The only way to tell is to look.

CPT invariance implies that particles and antiparticles have the same:
  • mass
  • charge-to-mass (except opposite sign)
  • magnetic moment (except opposite sign)
  • mean life
  • atomic structure
Testing to see whether particles and antiparticles have properties related in this way is thus a test of CPT invariance.

A simple explanation of CPT invariance is in a popular account of our low energy antiproton methods and Q/M measurements.

The Most Stringent Tests of CPT Invariance with Mesons, Leptons and Baryons

  • Important to check CPT invariance in at least one meson, lepton and baryon system

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