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 π 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.