The QCD analytic effective charge and its dependence on the pion mass

A new model for the QCD analytic running coupling, which incorporates the effects due to the pi meson mass, is proposed. The properties of this invariant charge in spacelike and timelike regions are examined. Its main distinctive features are a finite infrared limiting value, which depends on the pion mass, and the plateau-like behavior in the deep infrared domain of the timelike region.