Instanton-induced contributions to structure functions of deep inelastic scattering

We identify and calculate the instanton-induced contributions to deep inelastic scattering which correspond to nonperturbative exponential corrections to the coefficient functions in front of parton distributions of the leading twist.Comment: MPI-Ph/92-89 , LATEX, 15 pages, 3 figures incl. as uu-encoded fil

Valleys in Minkowski space and instanton-induced cross sections

We generalize the valley method for the calculation of instanton-induced cross sections, and reformulate it directly in the Minkowski space using the Keldysh diagram technique. The summation over all finite states is made implicit without our approach, and the fields of outgoing W-bosons are effectively taken into account by a classical field with specific analytic properties, which we call the “alien” field

Instanton-induced contributions of fractional twist to the cross section of hard gluon-gluon scattering in QCD

We study the instanton-induced cross section of hard gluon scattering in deep-inelastic kinematics. We find that the structure functions may possess numerically large nonperturbative contributions, which are related to Ringwald-type processes with the violation of chirality, and correspond to the exponential correction to the coefficient function in front of the parton distribution of the leading twist. Instanton-induced contributions are well defined for the structure function at the fixed value of the Bjorken scaling variable, and are probably absent in the moments. At intermediate virtualities of the order of Q2∼(30-50 GeV)2 these essentially nonperturbative contributions of fractional twist reach large values, of order 100-10-2 of the perturbative cross section, and remain at the same time under theoretical control