A non-perturbative effect in deep inelastic scattering

The HERA data at large Q2 and small-x investigate large distances on the light-cone. At such large distances the scattered quarks can maintain their colour identity, i.e. they remain colour non-singlets and confined, by polarizing the vacuum as they transfer energy to it. We calculate the probability for the creation of quark-antiquark pairs from the polarized QCD vacuum and their contribution to the structure function.