What are mass eigenstates and how do they relate to quarks and neutrinos?

[duck_21]

Hello, I have a couple of questions that have been confusing me for a while:
I read that quarks propagate as mass eigenstates, and that these are mixtures of the flavo eigenstates (superposition of the wave functions??), does this mean that baryons are the mass eigenstates of quarks? or does it mean that a free quark can exist as one flavor but be detected as another?? what exactly are mass eigenstates??
same questions go for neutrinos,
Thanx!

 

[malawi_glenn]

That is not at silly question.

This means that the eigenstates for the weak interaction is not the same as for the colour (strong) interaction and opposite. There is a mixing between these; more can be read in this old thread:

https://www.physicsforums.com/showthread.php?t=171190

Baryons are a composite system of 3 quarks, so it is not a quark eigenstate :S

 

[duck_21]

Thanks a lot!
So, there is an observable operator corresponding to the weak interaction (or flavor mix) and another one corresponding to the strong interaction (colour change) and the eigenstates of these operators are mixed to form mass (or propagation) eigenstates?? is this correct?

 

[malawi_glenn]

Well, yes sort of; and the mixing of the states are done through the matrix which has this "cabbibo angle" . You can roughly do the analogy with the Spin Z and X, Y operators; the eigenstates of the Sz-op are related to the eigenstates of Sx and Sy by an rotation matrix.

This site has a very good lecture note section, with Cabbibo mixing as one of the topics, and there are probably many more places that you can find this. Also a intro textbook in particle phyics is fun to have :)

http://hep.physics.utoronto.ca/~orr/wwwroot/phy357/Lect_2004.htm

 

[duck_21]

And what happens with neutrinos? they aren't colored, so is there an operator for flavor and another one for mass or propagation, which I'm guessing would be the free particle hamiltonian??

 

[malawi_glenn]

I am not an expert on this, but i know that the flavor and mass eigenstates of neutrinos are different, they change flavor as they propagate; evidence for mass.