QCD factorization for the pion diffractive dissociation to two jets

We calculate the cross section of a pion diffraction dissociation in two je ts with large transverse momenta originating from a hard gluon exchange bet ween the pion constituents. To the leading logarithmic accuracy tin energy) , the contribution coming From small transverse separations between the qua rk and the antiquark in the pion acquires the expected factorized form, the longitudinal momentum distribution of the jets being proportional to the p ion distribution amplitude. The hard gluon exchange can in this case be con sidered as a part of the unintegrated gluon distribution. Beyond the leadin g logarithms tin energy) this proportionality does not hold. Moreover, the collinear factorization appears to be broken by the end-point singularities . Remarkably enough, the longitudinal momentum distribution of the jets for the non-factorizable contribution is calculable, and turns out to be the s ame as for the factorizable contribution with the asymptotic pion distribut ion amplitude. (C) 2001 Elsevier Science B.V. All rights reserved.