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Q & A: How do the three neutrinos differ?

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Most recent answer: 06/19/2011
Q:
What is the difference between the three nuetrinos?
- Bob (age 19)
Seattle, WA
A:
The main difference is that they interact differently with the three flavors of charged spin 1/2 leptons:  electron, muon, and tau.   For example a high energy muon-type neutrino can interact with a neutron and produce a proton plus negative muon, but not a proton plus electron.   Why are there three?  We don't know.  That's the way it is.
The neutrinos have very-very small masses; their combined masses total no more than a few tenths of an electron-volt.  By comparison, an electron has a mass of 510x103 electron-volts.  Due to a quantum mechanical quirkiness, the flavor eigenstates are slightly different than the mass eigenstates.  They are mixtures.  This feature has also been observed in the system of neutral K mesons.  A consequence of this is that an electron type neutrino born from, say a neutron decay, can after some time oscillate into a muon type neutrino, and vice-versa. 
I recommend the Wikpedia article for more information. 

LeeH


(published on 06/19/2011)

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