Charmonium properties in deconfinement phase in anisotropic lattice QCD

الأصل · EN

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 ΔE ≡ E (APBC)-E (PBC)≃2√mc²+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/Ψand ηc channels for T≃(1.11-2.07)Tc. This fact indicates that J/Ψand 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 χc₁ at 1.62Tc.