Thermal properties of heavy-light quark pseudoscalar and vector mesons

Abstract

The thermal behaviour of the mass, leptonic decay constant, and width of heavy-light quark peseudoscalar and vector mesons is analized in the framework of thermal Hilbert moment QCD sum rules. In all the cases, the meson leptonic decay constants decrease with increasing T, and vanish at a critical temperature Tc, while the mesons develop a width which increases dramatically, diverging when T → Tc, where Tc is the temperature for chiral-symmetry restoration. The spectral function becomes a smooth function of the energy. This is interpreted as a signal for deconfinement at T = T c. In contrast, the thermal masses are stable, except when T → Tc, where the pseudoscalar meson mass increases slightly by 10-20%, and the vector meson mass decreases by some 20-30%.