Leading T3-behavior and vertex-configuration dependence of real-time thermal QCD coupling

Properties of effective coupling in the real time thermal QCD is in-vestigated at 1-loop order in the large T regime, focussing on its de-pendence on the vertex-momentum configuration at which the coupling is renormalized. It is shown explicitly that the effective coupling really suffers, as well as its strong dependence on the type of vertices (the tri-gluon, ghost-gluon and quark-gluon vertices), from a severe depen-dence on the momentum configuration (the symmetric and collinear confi-gurations as typical examples) of a vertex even after the type of vertex is specified. Another important observation is that the leading large-T behavior in general vertex configuration is cubic in T, a-1 ∼ T3, 1 power higher than previously expected. This behavior is solely controlled by those diagrams in which all of the 3 internal boson lines are represented by the temperature dependent thermal on-shell propaga-tors. Relation with the coupling defined in the imaginary time formalism is also discussed. (author). 8 refs.; 3 figs