- #1
Sidsid
- 16
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- Homework Statement
- Find the feynman diagrams for the following reactions (image)
- Relevant Equations
- None
Formation of quarks in Feynman diagrams
- Thread starter Sidsid
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SUMMARY
The discussion focuses on the formation of quarks in Feynman diagrams, specifically addressing the conversion of an anti-strange quark into an anti-down and up quark via weak interaction. Participants emphasize the importance of adhering to conservation laws, including charge conservation and strangeness. The conversation highlights the necessity of understanding the role of weak gauge bosons, particularly W bosons, in weak processes involving flavor change. The conclusion stresses that the leading contribution in such interactions typically involves only one W boson.
PREREQUISITES- Understanding of Feynman diagrams and particle interactions
- Knowledge of quark flavors and conservation laws
- Familiarity with weak interactions and gauge bosons
- Basic principles of quantum field theory
- Study the role of W and Z bosons in weak interactions
- Learn about quark flavor changes and their implications in particle physics
- Explore charge conservation in particle decays and interactions
- Investigate the significance of Lorentz invariance in particle physics
Particle physicists, students studying quantum field theory, and anyone interested in the dynamics of quark interactions and weak processes.
- #2
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Consider what the incoming and outgoing particles are and what vertices could possibly convert the incoming particles to the outgoing ones. Also be careful to satisfy conservation laws.
For example:
In the outgoing particles you have (after writing out the quark content): ##u\bar d \bar u d e^+ \nu_e##. There is no strange here so it seems strange (pun intended) to convert anything to an anti-strange. However, you should note that there are no strange quarks in the out state! So where did the strange quark go? What vertex could possibly violate strangeness? (Or quark flavour in general ...)
For example:
An anti-strange forming an anti-down and a strange would violate Lorentz invariance, so that is already a big no-no.Sidsid said:
In the outgoing particles you have (after writing out the quark content): ##u\bar d \bar u d e^+ \nu_e##. There is no strange here so it seems strange (pun intended) to convert anything to an anti-strange. However, you should note that there are no strange quarks in the out state! So where did the strange quark go? What vertex could possibly violate strangeness? (Or quark flavour in general ...)
- #3
Sidsid
- 16
- 2
Oh sorry that was a typo, i meant anti-strange -> anti-down and up via weak interaction.
- #4
Sidsid
- 16
- 2
- #5
- 22,820
- 14,860
I have written down what I could interpret from your diagram with some additional annotation:
Charges are noted in red. As you can see, your diagram violates charge conservation and has the incorrect outgoing quark content. It also has two weak gauge bosons. These are very massive and will generally lead to suppressed amplitudes. You should consider if both are necessary to do what you want to do.
Charges are noted in red. As you can see, your diagram violates charge conservation and has the incorrect outgoing quark content. It also has two weak gauge bosons. These are very massive and will generally lead to suppressed amplitudes. You should consider if both are necessary to do what you want to do.
- #6
- #7
Sidsid
- 16
- 2
Here is the last one. I would like to add by the wayy, that the exercise is focused on weak interaction.
- #8
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It is a weak process as it involves flavour change (the strangeness in the in and out states are different). However, that does not mean that there is only Ws or Zs, only that there is at least one.
In this case, the leading contribution will have only one W. Try to find it!
In this case, the leading contribution will have only one W. Try to find it!
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