g g , g p collisions

• High-energy photon can interact point-like (e.g. Compton scatt.) or quantum fluctuating into fermion-antifermion or vector-meson (J=1--):

• In practice: g  g0 , but g  V,qq fluctuations interact strongly and

• High-energy gg, gp collisions complementary to more “conventional” e+e-,