Charmonium properties in deconfinement phase in anisotropic lattice QCD
Abstract
J/Psi and etac above the QCD critical temperature Tc are studied in anisotropic quenched lattice QCD, considering whether the c c systems above Tc are spatially compact (quasi-)bound states or scattering states. We adopt the standard Wilson gauge action and O(a)-improved Wilson quark action with renormalized anisotropy as/at =4.0 at β=6.10 on 163× (14-26) lattices, which correspond to the spatial lattice volume V L3(1.55 fm)3 and temperatures T(1.11-2.07)Tc. We investigate the c c system above Tc from the temporal correlators with spatially-extended operators, where the overlap with the ground state is enhanced. To clarify whether compact charmonia survive in the deconfinement phase, we investigate spatial boundary-condition dependence of the energy of c c systems above Tc. In fact, for low-lying S-wave c c scattering states, it is expected that there appears a significant energy difference E E (APBC)-E (PBC)2mc2+3π2/L2-2mc (mc: charm quark mass) between periodic and anti-periodic boundary conditions on the finite-volume lattice. In contrast, for compact charmonia, there is no significant energy difference between periodic and anti-periodic boundary conditions. As a lattice QCD result, almost no spatial boundary-condition dependence is observed for the energy of the c c system in J/ and ηc channels for T(1.11-2.07)Tc. This fact indicates that J/ and ηc would survive as spatially compact c c (quasi-)bound states below 2Tc. We also investigate a P-wave channel at high temperature with maximally entropy method (MEM) and find no low-lying peak structure corresponding to c1 at 1.62Tc.
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