J/\Psi at high temperatures in anisotropic lattice QCD

TL;DR

This study uses anisotropic lattice QCD to investigate whether J/ and ta_c mesons remain as compact bound states above the QCD critical temperature, finding evidence for their survival up to about twice T_c.

Contribution

It provides lattice QCD evidence that J/ and ta_c can survive as compact states above T_c, using boundary-condition dependence analysis.

Findings

J/ and ta_c show no significant boundary-condition dependence above T_c.

Results suggest charmonia remain as quasi-bound states up to approximately 2T_c.

The study supports the survival of certain quarkonia in the quark-gluon plasma phase.

Abstract

J/\Psi and \eta_c above the QCD critical temperature T_c are studied in anisotropic quenched lattice QCD, considering whether the c\bar c systems above T_c are compact quasi-bound states or scattering states. We adopt the standard Wilson gauge action and O(a)-improved Wilson quark action with renormalized anisotropy a_s/a_t =4 at \beta=6.10 on 16^3\times (14-26) lattices, which correspond to the spatial lattice volume V\equiv L^3\simeq(1.55{\rm fm})^3 and temperatures T\simeq(1.11-2.07)T_c. To clarify whether compact charmonia survive in the deconfinement phase, we investigate spatial boundary-condition dependence of the energy of the c\bar c systems above T_c. In fact, for low-lying c \bar c scattering states, there appears a significant energy difference \Delta E \equiv E{\rm (APBC)}-E{\rm (PBC)} between periodic and anti-periodic boundary conditions as \Delta E\simeq2\sqrt{m_c^2+3\pi^2/L^2}-2m_c (m_c: charm quark mass) 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, we find almost 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, which indicates that J/\Psi and \eta_c would survive as compact c\bar c quasi-bound states below 2T_c.