The properties of D and D* mesons in the nuclear medium
We study the properties of $D$ and $D^*$ mesons in nuclear matter within a simultaneous self-consistent coupled-channel unitary approach that implements heavy-quark symmetry. The in-medium solution accounts for Pauli blocking effects, and for the $D$ and $D^*$ self-energies in a self-consistent manner. We pay a special attention to the renormalization of the intermediate propagators in the medium beyond the usual cutoff scheme. We analyze the behavior in the nuclear medium of the rich spectrum of dynamically-generated baryonic resonances in the C=1 and S=0 sector, and their influence in the self-energy and, hence, the spectral function of the $D$ and $D^*$ mesons. The $D$ meson quasiparticle peak mixes with $Σ_c(2823)N^{-1}$ and $Σ_c(2868)N^{-1}$ states while the $Λ_c(2595)N^{-1}$ mode is present in the low-energy tail of the spectral function. The $D^*$ spectral function incorporates $J=3/2$ resonances, and $Σ_c(2902)N^{-1}$ and $Λ_c(2941)N^{-1}$ fully determine the behavior of $D^*$ meson spectral function at the quasiparticle peak. As density increases, these resonant-hole modes tend to smear out and the spectral functions get broad. We also obtain the $D$ and $D^*$ scattering lengths, and optical potentials for different density regimes. The $D$ meson potential stays attractive while the $D^*$ meson one is repulsive with increasing densities up to twice that of the normal nuclear matter. Compared to previous in-medium SU(4) models, we obtain similar values for the real part of the $D$ meson potential but much smaller imaginary parts. This result can have important implications for the observation of $D^0$-nucleus bound states.