Dispersion relation of the rho meson in hot/dense nuclear matter

The dispersion relation of $\rho$ meson in both timelike and spacelike regimes in hot and dense nuclear medium is analyzed and compared with $\sigma $ meson based on the quantum hadrodynamics model. The pole and screening masses of $\rho $ and $\sigma$ are discussed. The behavior of screening mass of $\rho$ is different from that of $\sigma$ due to different Dirac- and Fermi-sea contributions at finite temperature and density.