Survival of charmonia above Tc in anisotropic lattice QCD

TL;DR

This study provides strong evidence that certain charmonium states, specifically J/ψ and ηc, remain as spatially localized bound states above the QCD critical temperature, indicating their survival in the quark-gluon plasma phase.

Contribution

The paper demonstrates the survival of J/ψ and ηc as bound states above Tc using boundary-condition dependence analysis and spectral functions in lattice QCD, a novel approach in this temperature regime.

Findings

J/ψ and ηc show no boundary-condition dependence above Tc

Spectral functions indicate these states remain as compact bound states

Survival persists up to approximately 2 times the critical temperature

Abstract

We find a strong evidence for the survival of $J/\Psi$ and $\eta_c$ as spatially-localized $c\bar c$ (quasi-)bound states above the QCD critical temperature $T_c$, by investigating the boundary-condition dependence of their energies and spectral functions. In a finite-volume box, there arises a boundary-condition dependence for spatially spread states, while no such dependence appears for spatially compact states. In lattice QCD, we find almost {\it no} spatial boundary-condition dependence for the energy of the $c\bar c$ system in $J/\Psi$ and $\eta_c$ channels for $T\simeq(1.11-2.07)T_c$. We also investigate the spectral function of charmonia above $T_c$ in lattice QCD using the maximum entropy method (MEM) in terms of the boundary-condition dependence. There is {\it no} spatial boundary-condition dependence for the low-lying peaks corresponding to $J/\Psi$ and $\eta_c$ around 3GeV at $1.62T_c$. These facts indicate the survival of $J/\Psi$ and $\eta_c$ as compact $c\bar c$ (quasi-)bound states for $T_c < T < 2T_c$.