Space-like and time-like pion electromagnetic form factor and Fock state   components within the Light-Front dynamics
  The simultaneous investigation of the pion electromagnetic form factor in the space- and time-like regions within a light-front model allows one to address the issue of non-valence components of the pion and photon wave functions. Our relativistic approach is based on a microscopic vector meson dominance (VMD) model for the dressed vertex where a photon decays in a quark-antiquark pair, and on a simple parametrization for the emission or absorption of a pion by a quark. The results show an excellent agreement in the space like region up to -10 $(GeV/c)^2$, while in time-like region the model produces reasonable results up to 10 $(GeV/c)^2$. 
J. P. B. C. de Melo (Centro de Ci\^encias Exatas e Tecnol\'ogicas,   Universidade Cruzeiro do Sul, Sao Paulo, SP., and Insti...