Charmonia in the Deconfined Plasma from Lattice QCD
We extract the spectral functions of $J/\psi$ and $\eta_c$ at finite
temperature ($T$) ranging from $T = 0.78T_c$ to $T = 2.33T_c$ by analyzing
correlation functions on $32^3\times(32-96)$ anisotropic lattices with the
maximum entropy method (MEM) ($T_c$ is the critical temperature of
deconfinement). In the analysis, we put special emphasis on the importance
of (I) the MEM error analysis of the resultant spectral functions and (II)
the study of the sensitivity of the spectral functions to the number of
temporal data points adopted in MEM. We find that $J/\psi$ and $\eta_c$
survive as distinct resonances in the plasma even up to $T \simeq 1.6 T_c$
and that they eventually dissociate around $1.6 T_c$. This result passes the
above two tests. The implication of this result in the physics of high
energy heavy ion collisions will be also discussed.