What is the origin of C,P and CP violations?

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Discussion Overview

The discussion revolves around the origins of C, P, and CP violations within the context of the electroweak model, exploring theoretical underpinnings, implications of handedness in fermions, and quark mixing mechanisms. It includes technical explanations and conceptual clarifications related to particle interactions and symmetries.

Discussion Character

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

Main Points Raised

  • One participant questions the neglect of fermion mass in weak interactions and its implications for the separation of left-handed and right-handed representations in the electroweak model.
  • Another participant asserts that mass is not neglected, explaining that electroweak interactions couple only to particles of one handedness, and that massive particles are represented as superpositions of chiral eigenstates.
  • A participant seeks clarification on the mixing of quark generations, noting that mass eigenstates differ from flavor eigenstates and that specific flavor eigenstates are superpositions of mass eigenstates.
  • There is a request for elaboration on the concept of mixing quarks via the exchange of virtual W bosons, with a participant questioning the conditions under which the superposition principle applies.
  • Participants inquire about the theoretical motivations behind the observation that fermions couple with only one handedness in electroweak interactions.
  • A historical reference is made to Wu's experiment, which observed polarization in beta decay as evidence of handedness asymmetry.
  • Another participant asks for the initial theoretical ideas that motivated the experiments related to handedness asymmetry.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the implications of mass in weak interactions and the mechanisms of quark mixing. There is no consensus on the conditions for applying the superposition principle or the initial theoretical motivations for handedness asymmetry.

Contextual Notes

Participants discuss various aspects of particle physics without resolving the complexities of mass eigenstates versus flavor eigenstates, and the specific conditions under which different principles apply. The discussion reflects ongoing exploration of these concepts.

ndung200790
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The C and P symmetry violations are deduced from the separating the right-handed representation from left-handed representation in electroweak model(Weinberg theory).Then I do not understand why we can consider the left-handed fermions living in a representation separating with that of right-handed fermions if it is not because of neglecting the mass of fermions in weak interaction(can we neglecting the mass?)?

The CP symmetry violation is deduced from the mixing three quark generations.Then I do not understand what allows the mixing of the three quarks?
 
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AFAIK, mass is not neglected. The point is that electroweak interaction only couples to electrons and neutrinos of one handedness. If the particles are massive, Then the energy eigenstates are 50-50 superpositions of chiral eigenstates but the particles produced in weak interaction aren't energy eigenstates.
 
ndung200790 said:
Then I do not understand what allows the mixing of the three quarks?
The mass eigenstates are different from the flavor eigenstates. If a specific flavor eigenstate is produced, it is a superposition of the mass eigenstates, and their relative phases change with time, giving components of other quarks.
Alternatively, you can describe mixing as the exchange of (2) virtual W bosons.
 
Why do you have to say their relative phase must be changed ''in time''?

Please elaborate the explaining the mixing caused by exchange (2) virtue W.Is it correct if I think that one generation of quarks can transforms to other generation of quarks by exchange virtue W bosons?Then we can(?) consider different flavor quarks can ''combine with each other''.Then what is the condition for applying superposition principle?
 
What suggests us about in electroweak interaction the fermions couple with only one handedness?
 
ndung200790 said:
What suggests us about in electroweak interaction the fermions couple with only one handedness?

There was a classic experiment by Wu who observed polarisation in beta decay.
 
Then what is the first theoretical idea about the handedness asymmetry?(I mean the motivate idea for the experiment)?
 
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