In the article, "What is spin", by Hans C. Ohanian we are shown how to take the wave-function for a Dirac electron with spin up and localized in space and then determine the momentum density in the Dirac field. The momentum density divides into two parts, a part that depends on the motion of the electron and another part that "is associated with circulating flow of energy in the rest frame of the electron". For a localized packet we learn that a circular "flow of energy" can be interpreted as electron spin.(adsbygoogle = window.adsbygoogle || []).push({});

Is the momentum density of a localized up Pauli electron similar or the same as the momentum density of a localized up Dirac electron? Do we still get a circular "flow of energy" with the Pauli electron?

A snippet of the paper follows, thanks for any help!

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# A Pauli and a Dirac electron, momentum density and spin.

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