Hadronic screening masses in the vector channel by the QCD sum rule

We calculate hadronic screening masses in the vector channel mode by using the QCD sum rule. We focus on the effect of the O(αs) correction to the Wilson coefficient of the identity operator. It is shown that the O(αs) correction cancels the effect of the gluon condensate and gives favorable results. It implies that the screening mass close to 2πT in the vector mode is no evidence for the existence of free quarks and gluons and that it results from the sum of all the perturbative and nonperturbative effects. We also show that the infrared divergence in three dimensional QCD, which is brought about by dimensional reduction, cancels each other and does not appear in the final results.