Name: jose Date: 05/05/10-04:08:23 PM Z
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