Drawing a Feynman Diagram for K^{*+}→K^0 + \pi^+

In summary, a Feynman diagram was discussed for the reaction K^{*+} \rightarrow K^0 + \pi^+. This reaction involves the K^{*+}-meson composed of an u and an anti-s quark, the K^0-meson composed of a d and an anti-s quark, and the \pi^+-meson composed of an u and an anti-d quark. The diagram depicted a gluon creating a quark-antiquark pair, with the assumption that the gluon was virtual. Feedback on the diagram was also mentioned. Time flows from left to right in the diagram.
  • #1
broegger
257
0
Hi

I have to draw a Feynman diagram for the following reaction:

[tex] K^{*+} \rightarrow K^0 + \pi^+ [/tex]

The [tex]K^{*+}[/tex]-meson is composed of an u and an anti-s quark, the [tex]K^0[/tex]-meson is composed of a d and an anti-s quark, and the [tex]\pi^+[/tex]-meson is composed of an u and an anti-d quark. I have drawn something like the following:

(EDIT: I have attached a picture of my diagram drawn in some demo-program instead, since I couldn't do it properly in text mode. The curly line represents a gluon creating a quark-antiquark pair. I have no experience drawing these things, so any feedback is very welcome :smile:)
 

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  • #2
Here's something i did in "Paint". It looks very much like the diagrams you find in Griffiths' text on Elementary Particles.

I hope it's not a weak decay. I assumed the gluon was virtual ([itex] K^{*+} [/itex] is a bound state, so there should be plenty of virtual gluons), so that's how two real quarks came out (one being the antiparticle of the other).

Daniel.

P.S. The arrow on the outgoing antiquark should be reversed and time "flies" from left to right.
 

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  • #3


Thank you for providing the diagram, it looks great! Just a few small corrections, the K^{*+} should have a quark-antiquark pair (u\bar{s}), the K^0 should have a quark-antiquark pair (d\bar{s}), and the \pi^+ should have a quark-antiquark pair (u\bar{d}). Also, the gluon line should be labeled as a gluon, not a quark. Other than that, your diagram accurately represents the reaction. Great job!
 

1. How do I draw a Feynman diagram for K*+ → K0 + π+?

To draw a Feynman diagram for this process, you will need to follow a few steps:

  • Identify the initial and final particles involved - in this case, K*+, K0, and π+.
  • Draw the particles as lines, with arrows indicating their direction of flow. The initial particle should be on the left and the final particles on the right.
  • Add the interaction vertices - the points where the particles interact. For this process, there will be two vertices, one for the decay of K*+ into K0 and π+, and one for the creation of K0.
  • Label the lines and vertices with the appropriate particles and their corresponding symbols.
  • Draw the Feynman diagram with the lines and vertices in the correct positions and orientations.

2. What are the symbols used for K*+, K0, and π+ in a Feynman diagram?

In a Feynman diagram, particles are represented by symbols that correspond to their names. For this process, the symbols used are K*+ for the K resonance particle, K0 for the neutral kaon, and π+ for the charged pion.

3. How do I know which particles can interact in a Feynman diagram?

In a Feynman diagram, only particles that conserve charge, energy, and momentum can interact. This means that the particles involved must have the same total charge before and after the interaction, as well as the same total energy and momentum. Additionally, the particles must have enough energy to interact, which is determined by their masses.

4. What is the significance of the arrows in a Feynman diagram?

The arrows in a Feynman diagram indicate the direction of flow for the particles. They show which particles are initial and final, and the direction of the interaction.

5. Can a Feynman diagram show the exact path of particles in a process?

No, a Feynman diagram does not show the exact path of particles in a process. Instead, it is a graphical representation of the interaction between particles and their corresponding symbols. It is a powerful tool for visualizing and understanding particle interactions, but it does not provide a precise depiction of the particles' paths.

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