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Part 1: Feynman Diagrams and Quantum Electrodynamics

The aim of putting my notes on “An Introduction to Quantum Field Theory by Peskin & Schroeder” to this webpage is to fill the gap on the derivations that the author of this book skipped because they are easy or, maybe author wants to test you if you have the sufficient background knowledge. I hope these notes will help someone who would like to do self-study this book and wants to quickly dive into its problems. There is a saying that you cannot learn physics fully just by understanding the formulation of the theory; you need to make your hands dirty by working on the problems by yourself. I will recommend reading these notes and book side by side.

There are couple of notes for the solution of this book problems in the internet which I’ve listed below but, please try to work first before looking at the solution.

If you find any typos in my notes or any suggestion (or comment), please write to me at damodar[At]


  • I will write vectors not in boldface (\mathbf{} in $\LaTeX$) but arrowhead (\vec{}). For example, the book uses vector $\mathbf{x}$, but I will use $\vec{x}$ instead. It is more convenient when you want to write it on paper. But, both notations mean the same.
  • $:=$ means defined as.
  • Imaginary number $i$ as just $i$ (i.e. i). I will not use $\iota$ (i.e. \iota).
  • Euler number $e$ as just $e$ (i.e. e) or sometimes $\exp$ (i.e. \exp).

Guidelines for naming the equation or statement:

  • In the book, the first paragraph after the section title has no indentation but rest of the paragraph have indentation. This means if I mean a paragraph, it should follow that way. Any middle paragraph without indentation is regarded as line breaks. Keep in mind!
  • If equation (that I want to prove) does not have numbering, I will write something like this: 13P4E5 means page number 13, paragraph 4, equation after four equations in the paragraph. Here I don’t count the inline equation which is inside the sentence. You may notice that the paragraph 4 ends at page 14. But, I will use page 13 to refer it because they are the same paragraphs.
  • If equation is numbered, I will write 15E(2.1) means page number 15, equation number (2.1).
  • If the equations are in same paragraphs, I may also write 13P4E5-8 or 15E(2.1)-(2.2).
  • If I prove the statement which is inside the paragraph, I will only write: 14P2 means page number 14, paragraph 2 and then, statement (for eg: “… statement” inclosed by blockquote).

Problem guides The author of the guides do not guarantee that their solutions are 100% correct. So, if you have doubt then I would recommend comparing among all.

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Published on Aug 24, 2021

Last revised on Aug 30, 2021