Heavy-light quark pseudoscalar and vector mesons at finite temperature

TL;DR

This paper investigates how heavy-light quark mesons' properties change with temperature, showing decay constants vanish and widths diverge at the critical temperature, signaling deconfinement and chiral-symmetry restoration.

Contribution

It provides a thermal QCD sum rule analysis of meson mass, decay constant, and width dependence on temperature, highlighting the disappearance of hadrons at the critical point.

Findings

Decay constants decrease and vanish at T_c

Widths increase and diverge at T_c

Masses show minimal change except near T_c

Abstract

The temperature dependence of the mass, leptonic decay constant, and width of heavy-light quark peseudoscalar and vector mesons is obtained in the framework of thermal Hilbert moment QCD sum rules. The leptonic decay constants of both pseudoscalar and vector mesons decrease with increasing $T$, and vanish at a critical temperature $T_c$, while the mesons develop a width which increases dramatically and diverges at $T_c$, where $T_c$ is the temperature for chiral-symmetry restoration. These results indicate the disappearance of hadrons from the spectral function, which then becomes a smooth function of the energy. This is interpreted as a signal for deconfinement at $T=T_c$. In contrast, the masses show little dependence on the temperature, except very close to $T_c$, where the pseudoscalar meson mass increases slightly by 10-20 %, and the vector meson mass decreases by some 20-30 %