We use QCD to compute the cross section for coherent production of a di-jet
(treated as a qqˉ moving at high relative transverse momentum,κt). In the target rest frame,the space-time evolution of this reaction is
dominated by the process in which the high κtqqˉ component of
the pion wave function is formed before reaching the target. It then interacts
through two gluon exchange. In the approximation of keeping the leading order
in powers of αs and all orders in
αsln(κt2/k02), the amplitudes for other processes are
shown to be smaller at least by a power of αs. The resulting dominant
amplitude is proportional to z(1−z)κt−4 (z is the fraction
light-cone(+)momentum carried by the quark in the final state) times the skewed
gluon distribution of the target. For the pion scattering by a nuclear target,
this means that at fixed xN=2κt2/s (but κt2→∞) the nuclear process in which there is only a single interaction is the
most important one to contribute to the reaction. Thus in this limit color
transparency phenomena should occur.These findings are in accord with E971
experiment at FNAL. We also re-examine a potentially important nuclear multiple
scattering correction which is positive and ∝A1/3/κt4. The
meaning of the signal obtained from the experimental measurement of pion
diffraction into two jets is also critically examined and significant
corrections are identified.We show also that for values of κt achieved
at fixed target energies, di-jet production by the e.m. field of the nucleus
leads to an insignificant correction which gets more important as κt
increases.Comment: 23 pages, 9 figure