Feynman Diagrams

Complete the following tasks

If you want to submit hand-drawn work (graphs, equations, etc) by taking photos of the work and uploading the images, that is acceptable so long as the work in the images is legible.

In this assignment you’re going to do some quantum field theory!

1. How are the number of external lines related to the number of internal lines and vertices? Explain how you arrived at your answer.

2. If I tell you the number of external lines with arrows point inward, can you tell me the number of external lines with arrows pointing outward? Does a similar relation hole for the number of external wiggly lines? Explain how you arrived at your answer.

3. Draw a Feynman diagram in which you start with one electron and end up with one positron.

4. Draw three different Feynman diagrams where an electron and a photon interact to produce 3 electrons, 2 positrons, and 2 photons.

5. Draw a diagram in which 2 electrons scatter off each other (in other words, you start with 2 electrons, and end up with 2 electrons, but in the middle they interact).

6. Draw a diagram for inverse beta decay (a proton and an electron come together to produce a neutron and electron neutrino).

7. Translate the diagrams in questions 4, 5 and 6 into mathematical expressions using the rules laid out in the box “Doing Physics with Feynman Diagrams” on page 159 of “Physics and Feynman Diagrams” by David Kaiser. (se the attched file)

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