Heavy-light quark pseudoscalar and vector mesons at finite temperature

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 constant of both pseudoscalar and vector mesons decreases with increasing T, and vanishes at a critical temperature Tc, while the mesons develop a width which increases dramatically and diverges at Tc, where Tc is the temperature for chiral-symmetry restoration/quark-gluon deconfinement. 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 = Tc. In contrast, the masses show little dependence on the temperature, except very close to Tc, where the pseudoscalar meson masses increase slightly by 10-20%, and the vector meson masses decrease by some 20-30%.