Charmonium properties at finite temperature on quenched anisotropic lattices

We study charmonium properties below and above $T_c$ up to 1.8$T_c$, on quenched anisotropic lattices. Information of the spectral functions is extracted using the maximum entropy method and the constrained curve fitting. We also calculate the color singlet and averaged free energies and evaluate the charmonium spectrum with the potential model analysis. The relation between the lattice result of the spectral function analysis and the potential model is discussed.Comment: Lattice2004(non-zero), 3 pages, 4 figure

Charmonium near the deconfining transition on the lattice

We study the charmonium properties at finite temperature using quenched lattice QCD simulations. Although a simple potential model analysis indicates no bound state at $T>1.05T_c$, our analyses of the spatial correlation between quark and anti-quark and the spectral function indicate that a bound-state-like structure may survive even above $T_c$.Comment: 4 pages, 3 figures, Talk presented at the PANIC02 conference, Sept. 30 - Oct. 4, 2002, Osaka, Japa

Charmonium at finite temperature in quenched lattice QCD

We study charmonium correlators in pseudoscalar and vector channels at finite temperature using lattice QCD simulation in the quenched approximation. Anisotropic lattices are used in order to have sufficient numbers of degrees of freedom in the Euclidean temporal direction. We focus on the low energy structure of the spectral function, corresponding to the ground state in the hadron phase, by applying the smearing technique to enhance the contribution to the correlator from this region. We employ two analysis procedures: the maximum entropy method (MEM) for the extraction of the spectral function without assuming a specific form, to estimate the shape of the spectral function, and the standard $\chi^2$ fit analysis using typical forms in accordance with the result of MEM, for a more quantitative evaluation. To verify the applicability of the procedures, we first analyze the smeared correlators as well as the point correlators at zero temperature. We find that by shortening the $t$-interval used for the analysis (a situation inevitable at $T>0$) the reliability of MEM for point correlators is lost, while it subsists for smeared correlators. Then the smeared correlators at $T\simeq 0.9 T_c$ and $1.1 T_c$ are analyzed. At $T\simeq 0.9 T_c$, the spectral function exhibits a strong peak, well approximated by a delta function corresponding to the ground state with almost the same mass as at T=0. At $T\simeq 1.1 T_c$, we find that the strong peak structure still persists at almost the same place as below $T_c$, but with a finite width of a few hundred MeV. This result indicates that the correlators possess a nontrivial structure even in the deconfined phase.Comment: 19 pages, 26 figure

Quarkonium at finite temperature

Lattice QCD studies on charmonium at finite temperature are presented After a discussion about problems for the Maximum Entropy Method applied to finite temperature lattice QCD, I show several results on charmonium spectral functions. The ``wave function'' of charmonium is also discussed to study the spatial correlation between quark and anti-quark in deconfinement phase.Comment: 8pages, 4figures, talk presented at Hard Probes 200