# Neutrino mixing

## Main Question or Discussion Point

On page 3 of the following pdf:
http://pdg.lbl.gov/2005/reviews/numixrpp.pdf

the paragraph after equation 13.12, there's a line that says:
"Thus, if U is not real, the neutrino..... When CPT holds, any difference between these probabilities indicates a violation of CP invariance."

I don't understand how it should be a violation of CP invariance, and not CPT invariance that is violated.

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CarlB
Homework Helper
It's correct, but confusing. When the author writes "any difference between these probabilities", by "these probabilities" he refers to the probabilities calculated in equation (13.8), not the probabilities calculated in (13.12).