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So I know that Noether's theorem has a symmetry that corresponds to a conservation law.

I was wondering what quantity is conserved in charge conjugation symmetry.

Qmechanic
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averageenjoyer1234
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    Note that Noether's theorem applies to continuous symmetries, but charge conjugation is a discrete transformation, not a continuous one. – Albert Jul 21 '23 at 14:40
  • Also, note that CPT is the only combination of C, P, and T that is observed to be an exact symmetry at the fundamental level (plus, the "CPT theorem" says that any Lorentz-invariant local QFT with a hermitian Hamiltonian is CPT symmetric). See also: CPT Violation and Symmetry-Conservation Laws – Quillo Jul 21 '23 at 16:31
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    Related: https://physics.stackexchange.com/q/8518/2451 – Qmechanic Jul 21 '23 at 18:38
  • @Quillo And that is a synopsis of patterns observed in the fundamental experiments: it is not, itself, fundamental. – John Doty Jul 21 '23 at 18:41
  • @JohnDoty I mean that CPT is (to my understanding) considered to be an experimentally informed requirement (i.e. no observations so far tell us that CPT is broken). I am not sure to understand your comment, what do you exactly mean? – Quillo Jul 21 '23 at 20:21
  • @Quillo "CPT is a symmetry of nature" is a summary of known experimental results. The experiments that confirm this are fundamental, and they will remain fundamental even if some other experiment falsifies CPT symmetry in the future. They'll suggest to us under what conditions CPT is a symmetry. Theories come and go, but experimental results remain. For example, Galileo's experiments remain fundamental to our understanding of gravity, while the theory of gravity has changed in major ways since his time. – John Doty Jul 21 '23 at 21:01

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