#degrees of polarization of a spin 1 or 2 particle On page 32 of Quantum Field Theory by A. Zee, he expects you to remember the concept of polarization, specifically how to extract the number of degrees of polarization of a spin 1 or 2 particle. As I seem to remember from EM class, polarization is something like the dipole moment per unit volume, or the number dimensions perpendicular to a given line of propagation in a wave. Nothing like Zee suggests. My memory is fading here. Can anyone give me a good reference for this, so I can read up on it? Or explain, if possible, why polarization is so important here, and how to determine the number of degrees of polarization for a spin m particle?