Charmonium dissociation temperatures in quenched lattice QCD

We study charmonium dissociation temperatures using lattice QCD. The dissociation temperatures of J/ψ, ψ0, and χc states play key roles in sequential J/ψ suppression scenarios. To distinguish a bound state from the scattering states, charmonium spectral functions have been studied on the lattice using e.g. the Maximum Entropy Method. Recently, however, we have pointed out that a constant mode in finite temperature meson correlators can lead to misleading conclusions about the stability of charmonium states when the constant mode is not removed in the spectral function [1]. In this study, we adopt a finite volume method [2] taking into account the effects of the constant mode. We investigate the charmonium mass spectra under different spatial boundary conditions. We combine a variational analysis to improve the signals of excited states such as ψ0 states. Besides the dissociation temperatures, we discuss the temperature dependence of the wave function (the Bethe-Salpeter amplitude) of the charmonia [3] to see whether the c-quark and c̄-quark stay together with each other or not above Tc. Here we present figures for the latter calculations. The left panel shows the volume dependence of S-wave state wave functions. The variational analysis can provide not only lowest state wave funcion but also next lowest one. The right panel shows the same result for P-wave states. We can not find any signals of charmonium dissociation at T = 2.3Tc even in P-wave states. The results are important to discuss J/ψ suppression scenarios in heavy ion collision experiments. The simulations have been performed on supercomputers (NEC SX-5) at the Research Center for Nuclea