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

TL;DR

This study uses thermal QCD sum rules to analyze how charmonium properties like mass, width, and coupling change with temperature, suggesting J/psi may survive past the deconfinement transition.

Contribution

It provides a detailed thermal evolution of J/psi parameters using QCD sum rules, highlighting behavior different from light and heavy-light systems and indicating potential survival beyond T_c.

Findings

J/psi mass remains constant over a wide temperature range.

Total width increases then sharply decreases near T_c.

Resonance coupling increases monotonically around T_c.

Abstract

The thermal evolution of the hadronic parameters of charmonium in the vector channel, i.e. the J/psi 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 \simeq 1.22T_c (m_Q is the charm quark mass) and the J/psi 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 \simeq 1.04T_c beyond which it decreases sharply with increasing T. The resonance coupling is also initially constant beginning to increase monotonically around T \simeq T_c. This behavior strongly suggests that the J/psi resonance might survive beyond the critical temperature for deconfinement, in agreement with lattice QCD results.