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

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Discussion Overview

The discussion revolves around the concepts of mass eigenstates in the context of quarks and neutrinos, exploring their definitions, relationships to flavor eigenstates, and implications for particle interactions. It touches on theoretical aspects and the nature of particle mixing in weak and strong interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether baryons are mass eigenstates of quarks or if free quarks can exist as one flavor but be detected as another.
  • Another participant clarifies that the eigenstates for weak and strong interactions are different and that baryons are composite systems of quarks, not quark eigenstates.
  • A participant proposes that there are observable operators corresponding to weak and strong interactions, and that mass eigenstates are formed from the mixing of these operators' eigenstates.
  • Discussion includes the mention of the Cabibbo angle and analogies to spin operators to explain the mixing of states.
  • One participant raises a question about neutrinos, suggesting that there are operators for flavor and mass, with the implication that neutrinos change flavor as they propagate.
  • A later reply asserts that the flavor and mass eigenstates of neutrinos are different, indicating evidence for mass through flavor change during propagation.

Areas of Agreement / Disagreement

Participants express various viewpoints on the nature of mass and flavor eigenstates, with some agreement on the distinction between weak and strong interactions, but no consensus on the implications for quarks and neutrinos.

Contextual Notes

Limitations include the lack of detailed definitions for mass and flavor eigenstates, as well as the dependence on specific theoretical frameworks that may not be universally accepted.

Who May Find This Useful

This discussion may be of interest to those studying particle physics, particularly in understanding the behavior of quarks and neutrinos in relation to their mass and flavor eigenstates.

duck_21
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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!
 
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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
 
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?
 
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
 
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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??
 
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.
 

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