- #1
MathematicalPhysicist
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- The reference is the final project on pages 775-777 of Peskin's and Schroeder's textbook on QFT.
And the solution from here:
https://zzxianyu.files.wordpress.com/2017/01/peskin_problems.pdf
on page 194.
My problem is on page 194 of the solution, where he writes: ##\frac{1}{2}\delta^{ab}\frac{1}{2}\delta^{ab}=2##.
I assume there are three colours and thus ##a,b \in \{ 0,1,2 \}##.
So I get: ##\delta^{ab}\delta^{ab} = \delta^{00}\delta^{11}+\delta^{11}\delta^{00}+\delta^{11}\delta^{22}+\delta^{22}\delta^{11}+\delta^{22}\delta^{00}+\delta^{00}\delta^{22}+\delta^{22}\delta^{22}+\delta^{11}\delta^{11}+\delta^{00}\delta^{00}=9##, so in the above equation in the solution shouldn't it be: ##9/4=2.25## and not ##2## as it's written in this solution?
I assume there are three colours and thus ##a,b \in \{ 0,1,2 \}##.
So I get: ##\delta^{ab}\delta^{ab} = \delta^{00}\delta^{11}+\delta^{11}\delta^{00}+\delta^{11}\delta^{22}+\delta^{22}\delta^{11}+\delta^{22}\delta^{00}+\delta^{00}\delta^{22}+\delta^{22}\delta^{22}+\delta^{11}\delta^{11}+\delta^{00}\delta^{00}=9##, so in the above equation in the solution shouldn't it be: ##9/4=2.25## and not ##2## as it's written in this solution?