PHOTON POLARIZATION OPERATOR IN AN EXTERNAL NON-ABELIAN FIELD

The contribution of massive spin-0, isospin-1/2 particles to the photon polarization operator in the background non-Abelian constant field is calculated. We have considered the spherically symmetric chromomagnetic field Bai=λδai. Such model vacuum is shown to be gyrotropic in spite of the fact that it is stable with respect to creation of pairs of real particles. At large Euclidean photon momentum the leading power term in the polarization operator is exactly determined by the value of scalar quark condensate. Its contribution to the scale-breaking correction to the deep inelastic scattering cross-section is also calculated in the paper. The gauge- and Lorentz-invariant averaging of the polarization operator over the ensemble of vacuum fields of various orientations is performed. © 1990 Springer-Verlag.