# Is it a misprint in QFT book of Peskin?

1. Jan 14, 2013

### ndung200790

In QFT book of Peskin&Schroeder writing(page 252,section 7.5Renormalization of electric Charge):
(e$^{2}$-e$^{2}_{0}$)/e$^{2}_{0}$=$\delta$Z$_{3}$$\approx$-2$\alpha$/3$\pi$$\epsilon$.

Where $\epsilon$ is 4-d(d is dim of space-time)

But I think that it is misprint,because bare charge>> observed charge e,then the right formular would be (e$^{2}$-e$^{2}_{0}$)/e$^{2}$=.........

2. Jan 14, 2013

### ndung200790

I have found out the errata and that is not misprint.Then I do not understand the formula,because (e^2-e0^2) is the same order with e0^2 then (e^2-e0^2)/e0^2 can not be divergent as Peskin(~2*anpha/3*pi*epsilon)?

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