The effective \omega-meson mass with a vector field self-interaction
  We calculate the effective mass m_\omega^* of the \omega-meson in nuclear medium by the \sigma-\omega model with a vector field self-interaction (VFSI). We found that the direct and the indirect effects of the VFSI almost cancel each other and the result is changed only slightly at the normal density. The VFSI makes m^*_\omega smaller at lower density and makes m_\omega^* larger at higher density. However, both effects are not large. 
Katsuaki Sakamoto, Hiroaki Kouno, Akira Hasegawa and Masahiro Nakano