The effective mass and screening mass of the rho meson for the vector dominance model and the vector coupling model at finite temperature and density

In the framework of thermo-field dynamics, the temperature and/or density dependences of the effective mass and the screening mass of the rho-meson for the vector dominance model and the nucleon-nucleon-rho-meson (NN rho ) vector coupling model have been calculated. We have found that for the vector dominance model, the effective mass and the screening mass of the rho-meson increase with temperature, and for the NN rho vector coupling model, they remain almost unchanged with temperature, but increase with density. (author)