"Does every electron neutrino start with the same mixture, or is it determined by the kinematics?"
Every electron neutrino has the same values of ιᾢ up to an overall phase; these numbers are 3 entries of a famous matrix that says how flavor eigenstates are linear combinations of mass eigenstates.
It's called the PMNS matrix, or PontecorvoâMakiâNakagawaâSakata matrix.
In my post, I was using the inverse matrix to express mass eigenstates in terms of flavor eigenstates! Like this:
⢠the νâ is 68% electron neutrino, 10% mu neutrino and 22% tau neutrino.
⢠the νâ is 30% electron, 36% mu and 34% tau.
⢠the νâ is 2% electron, 48% mu and 50% tau.
But these numbers are absolute values squared of the matrix elements, so we get probabilities.
https://en.wikipedia.org/wiki/Pontecorvo%E2%80%93Maki%E2%80%93Nakagawa%E2%80%93Sakata_matrix