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Ussualy one replace the sum over polarization vectors with -g_{\mu \nu} for a massless particle (abelian).

For a particle with mass, \frac{k^{\mu } k^{\nu }}{k^{2}}-g^{\mu \nu }.

How can i get only the transversal polarization? or the longitudinal?

Thanks in advance

**Next message:**hayam yassin: "How i can calculate the branching ratio by Feyncalc?"**Previous message:**Jorge Romão: "FeynCalc and Mathematica 7"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

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