Thermal Relaxation of Charm in Hadronic Matter

Understand

The thermal relaxation rate of open-charm ($D$) mesons in hot and dense hadronic matter is calculated using empirical elastic scattering amplitudes.

• $D$-meson interactions with thermal pions are approximated by $D^*$ resonances, while scattering off other hadrons ($K$, $\eta$, $\rho$, $\omega$, $K^*$, $N$, $\Delta$) is evaluated using vacuum scattering amplitudes as available in the literature based on effective Lagrangians and constrained by realistic spectroscopy.
• The thermal relaxation time of $D$-mesons in a hot $\pi$ gas is found to be around 25-50\,fm/$c$ for temperatures $T$=150-180\,MeV, which reduces to 10-25\,fm/$c$ in a hadron-resonance gas.
• The latter values, argued to be conservative estimates, imply significant modifications of $D$-meson spectra in heavy-ion collisions.