Feynman Diagram: Simga+ -> p + gamma?

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Homework Help Overview

The discussion revolves around the decay process of the sigma plus baryon (Ʃ+) into a proton (p) and a photon (γ), specifically focusing on how to represent this decay using a Feynman diagram. The subject area includes particle physics, particularly quantum electrodynamics (QED) and quantum chromodynamics (QCD).

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the importance of considering the quark composition of the sigma baryon and how it relates to the decay process. Questions are raised about the interactions of individual quarks and whether certain decay processes are allowed based on conservation laws.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the decay process and the implications of quark interactions. Some guidance has been provided regarding the need to consider individual quarks in the decay, but there is no explicit consensus on the specifics of the decay process or the validity of proposed interactions.

Contextual Notes

Participants are navigating the complexities of quark interactions and conservation laws, with some uncertainty regarding the allowed processes in the context of weak interactions.

Dr.Brule
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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 + \gamma

Should I consider the quark composition of the sigma first?

Thanks a lot.
 
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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).
 


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?
 


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?
 

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