Hello everyone, I have a problem with deriving following equality:(adsbygoogle = window.adsbygoogle || []).push({});

\begin{equation}

u^{s}(p) \bar{u}^{s}(p) = 1/2 ((\slashed{p} + m)(1+\gamma^5 \slashed{s}))

\end{equation}

where s is spin 4-vector. I know how to calculate this tensor product when there is spin sum in front of it, but without the sum, I am clueless. Can someone help me, please? Thank you.

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# QED spin matrix

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