# Back-of-the-envelope calculation of electron anomalous magnetic moment

I wonder if there is an intuitive way to obtain the $\frac{\alpha}{2\pi}$ correction to electron's $\frac12 (g-2)$ just like how Bethe estimated the Lamb shift?

Here is an attempt by Drell & Pagels (dispersion relation) http://prola.aps.org/abstract/PR/v140/i2B/pB397_1

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relevant books.google.com/… –  pcr Nov 14 '11 at 3:54