Charmonium correlators at finite temperature in quenched lattice QCD

We study charmonium correlators at finite temperature using quenched lattice QCD simulations. Two analysis procedures are applied to extract information on the spectral function: the maximum entropy method, and the $\chi^2$ fit analyses including the constrained curve fitting. We focus on the low energy structure of the spectral function by applying the smearing technique. We first discuss the applicability of these methods to the finite temperatures by analyzing the data at T=0 with restricted numbers of degrees of freedom. Then we apply these methods to the correlators at $T>0$. We find no indication of mass shift and finite width for the charmonium states at $T\simeq 0.9T_c$. The results at $T\simeq 1.1 T_c$ imply that bound-state-like structures may survive even above $T_c$.