Open charm in nuclear matter at finite temperature

Abstract

We study the properties of open-charm mesons ($D$ and $\overline{D}$) in nuclear matter at finite temperature within a self-consistent coupled-channel approach. The meson-baryon interactions are adopted from a type of broken SU(4) $s$-wave Tomozawa-Weinberg term supplemented by an attractive scalar-isoscalar interaction. The in-medium solution at finite temperature incorporates Pauli blocking effects, mean-field binding on all the baryons involved, and \ensuremath{\pi} and open-charm meson self-energies in a self-consistent manner. In the $\mathit{DN}$ sector, the ${\ensuremath{\Lambda}}_{c}$ and ${\ensuremath{\Sigma}}_{c}$ resonances, generated dynamically at 2593 and 2770 MeV in free space, remain close to their free-space position while acquiring a remarkable width due to the thermal smearing of Pauli blocking as well as from the nuclear matter density effects. As a result, the $D$ meson spectral density shows a single pronounced peak for energies close to the $D$ meson free-space mass that broadens with increasing matter density with an extended tail particularly toward lower energies. The $\overline{D}$ potential shows a moderate repulsive behavior coming from the dominant $I=1$ contribution of the $\overline{D}N$ interaction. The low-density theorem is, however, not a good approximation for the $\overline{D}$ self-energy in spite of the absence of resonance-hole contributions close to threshold in this case. We speculate the possibility of $D$-mesic nuclei as well as discuss some consequences for the $J/\ensuremath{\Psi}$ suppression in heavy-ion collisions, in particular for the future CBM experiment at FAIR.