The phi meson at high temperatures and densities

The spectral density of the phi meson in a hot bath of nucleons and pions is calculated by relating the vector meson self-energy to the forward scattering amplitude, which is constrained by experimental data. Dispersion techniques are used to verify the relationship between real and the imaginary parts of the in-medium self energy. The position of the spectral peak of the phi meson is found to be shifted from its vacuum position by only a small amount, but its width is considerably increased.