QCD sum rules and thermal properties of Charmonium in the vector channel

Abstract

The thermal evolution of the hadronic parameters of charmonium in the vector channel, i.e. the J / ψ resonance mass, coupling (leptonic decay constant), total width, and continuum threshold is analyzed in the framework of thermal Hilbert moment QCD sum rules. The continuum threshold s 0 , as in other hadronic channels, decreases with increasing temperature until the PQCD threshold s 0 = 4 m Q 2 is reached at T ≃ 1.22 T c ( m Q is the charm quark mass) and the J / ψ mass is essentially constant in a wide range of temperatures. The other hadronic parameters behave in a very different way from those of light-light and heavy-light quark systems. The total width grows with temperature up to T ≃ 1.04 T c beyond which it decreases sharply with increasing T. The resonance coupling is also initially constant beginning to increase monotonically around T ≃ T c . This behavior strongly suggests that the J / ψ resonance might survive beyond the critical temperature for deconfinement, in agreement with lattice QCD results.