Feynman Diagram: Simga+ -> p + gamma?

In summary, the conversation discusses how to draw a Feynman diagram for the decay of a Sigma particle into a proton and a photon. The participants mention considering the quark composition of the Sigma and how individual quarks and leptons are involved in QED/QCD interactions. They also discuss the possibility of a d quark combining with the left s quark and the limitations of certain weak interaction processes involving quarks.
  • #1
Dr.Brule
3
0
Feynman Diagram: Simga+ --> p + gamma?

Hi,

Can anyone give me some indications as to how to draw the feynman diagram for the following decay?

Ʃ+ → p + [itex]\gamma[/itex]

Should I consider the quark composition of the sigma first?

Thanks a lot.
 
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  • #2


Dr.Brule said:
Should I consider the quark composition of the sigma first?

Thanks a lot.

Indeed. All of the QED/QCD interactions involve individual quarks and leptons, not composite particles. So you want to consider what happens to each quark in the sigma particle independently (at least, to get a first approximation to the decay).
 
  • #3


Steely Dan said:
Indeed. All of the QED/QCD interactions involve individual quarks and leptons, not composite particles. So you want to consider what happens to each quark in the sigma particle independently (at least, to get a first approximation to the decay).

So I get how the two u quarks would combine with a d quark to form the proton, but would you get this d quark with the s quark that's left?

Is the process s --> u + anti u ---> ONE gamma allowed?
 
  • #4


Dr.Brule said:
So I get how the two u quarks would combine with a d quark to form the proton, but would you get this d quark with the s quark that's left?

Is the process s --> u + anti u ---> ONE gamma allowed?

No, that process does not conserve electric charge. What weak interaction processes involving quarks did you learn about?
 
  • #5


Hello,

To draw the Feynman diagram for this decay, you should first consider the quark composition of the sigma particle. The sigma particle is composed of three quarks: two up quarks and one down quark. Therefore, the Feynman diagram for this decay would involve the interaction of these three quarks.

Next, you should consider the interaction between the quarks and the exchange of particles that leads to the decay. In this case, the sigma particle decays into a proton and a photon. This decay can be represented by the exchange of a W boson, which carries the weak force. The W boson interacts with the down quark in the sigma particle, changing it into an up quark and creating a proton. The W boson also emits a photon, representing the electromagnetic force, which carries away the excess energy from the decay.

Overall, the Feynman diagram for this decay would involve the interaction of the three quarks in the sigma particle, the exchange of a W boson, and the creation of a proton and a photon. I hope this helps!
 

FAQ: Feynman Diagram: Simga+ -> p + gamma?

1. What is a Feynman Diagram?

A Feynman diagram is a visual representation used in particle physics to depict the interactions between subatomic particles. It was developed by physicist Richard Feynman in the 1940s and is based on his theory of quantum electrodynamics.

2. What does the notation "Sigma+ -> p + gamma" mean in a Feynman diagram?

The notation "Sigma+ -> p + gamma" represents the decay of a Sigma+ particle into a proton (p) and a gamma ray (gamma). The arrow indicates the direction of time, and the wavy line represents the exchange of a virtual photon between the particles.

3. What is the significance of the Feynman diagram in particle physics?

Feynman diagrams are important tools for understanding and predicting the behavior of subatomic particles. They allow physicists to visualize and calculate the probability of particle interactions and reactions, providing a framework for studying the fundamental forces of nature.

4. How are Feynman diagrams used in experimental particle physics?

In experimental particle physics, Feynman diagrams are used to interpret data from particle collisions and validate the Standard Model of particle physics. By comparing the predicted Feynman diagrams to the observed data, physicists can determine the particles involved in a collision and their properties.

5. Are there any limitations or criticisms of the Feynman diagram?

While Feynman diagrams are a powerful tool, they have been criticized for oversimplifying and only representing a limited number of interactions. They also do not account for the effects of virtual particles, which can complicate calculations. However, they remain an essential tool in particle physics research and have contributed significantly to our understanding of the subatomic world.

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