Class #1 (Jan. 17) Reading Questions - Particle Physics, Sec. 4; Handout pgs. 59-66



1. The Dirac equation, the relativistic wave equation for spin 1/2 particles, involves a 4-component wave-function (usually represented as a column vector).  What is the physical interpretation of the four components?


2. According to the handout how do you distinguish a particle from an antiparticle in a Feynman diagram? Based on the handout, what is wrong with the QED diagrams shown in Figs. 4.3 and 4.4 of our text.  [By the way, correctly drawn Feynman diagrams provide a visual representation of the Feynman-Stuckelberg interpretation of Dirac's "sea of negative energy particles".]


3. What is a "virtual" particle? How do you distinguish real particles from "virtual" particles in a Feynman diagram?


4. Why does one typically not bother calculating QED Feynman diagrams with more than say 4 vertices?


5. What is meant by renormalization?  People often talk about the "bare electron mass".  What do you think this means?



Your Question:  Please give a well formulated question that you have regarding the material covered in this reading assignment.