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Barmecides
#11
Feb29-08, 02:29 AM
P: 79
Quote Quote by Vanadium 50 View Post
Suppressed by the mechanism of Glashow, Illiopoulos and Maiani. This is a cancellation that occurs in flavor changing neutral currents: decays like K0L -> mu+ mu- and pi0 -> nu nubar. If the neutrinos were exactly degenerate the cancellation would be exact and this decay wouldn't occur. Because they have slightly different masses, the decays are suppressed.
Hello Vanadium,

GIM mechanism start to be old for me last time I studied it.
I understand that for K0 we have FCNC, but why can't we have :
u ubar + ... -> Z0 -> nu nubar ?
This diagram is suppressed by mnu/MZ, but why do we need CKM and stuff like that ?
Can you explain a bit more ?