Polarization Effects of Vector-Mesons

Adopting a vector-meson model for the $\pi$-meson we study (I) the polarization of $\pi$-mesons produced in nucleon-nucleon-collisions; (II) the angular distribution of $\mu$-mesons resulting from $\pi -\mu$-disintegrations, as depending on the polarization of the $\pi$-mesons; (III) the effect of electromagnetic fields on this polarization, in particular; (IV) the depolarization caused by the electric fields in matter. The theoretical results are encouraging for an experimental investigation.