P-Wave Polarization of the rho-Meson and the Dilepton Spectrum in Dense Matter

We study the $p$-wave polarization operator of the $\rho$-meson due to $\rho N$ interactions via the $N^*$ (1720) and $\Delta (1905)$ resonances and compute the corresponding production rate for $e^+e^-$-pairs at finite temperature and baryon density. At high baryon density we find a significant shift of the spectrum to lower invariant masses.