Decay constants of heavy vector mesons at finite temperature

This study deals with determination of the decay constants of heavy vector mesons in the framework of the thermal QCD sum rules. We calculate both thermal spectral density and non-perturbative contributions taking into account the traditionally existing operators at T = 0 and also additional operators appearing at finite temperature. Analysis of the obtained thermal sum rules shows that the decay constants almost remain unchanged with respect to the variation of temperature up to T congruent to 100 M e V, however after this point, they start to decrease sharply with increasing temperature.