Nuclear Transparency and Light Cone Pion Wave Function in the Coherent Pion-Nucleon and Pion-Nucleus Production of Two Jets at High Relative Momenta

In the target rest frame at fixed x = 2κ ²_t/s, with κ ²_t -> ∞ , the space-time evolution of coherent high κ_t di-jet production is dominated by the formation of a high κ _t qbar {q} component (point like configuration) before the incident pion reaches the target. This point like configuration then interacts through two gluon exchange with the target, leading to disappearance of initial and final state interaction effects. These predictions are in accord with the FNAL data. We compute the cross section in the approximation of keeping the leading order(LO) in powers of α_s, and in the leading log approximation in α _sIn(κ ²_t/Λ ²_QCD). Amplitudes for other processes are shown to be smaller by at least a power of α_s. Thus the high κ_t component of pion wave function, can be measured at sufficiently large values of κ ²_t. The resulting dominant amplitude is proportional to z(1 - z)α _s(κ ²_t)/κ ^-4_t(ln κ ²_t/Λ ²)^C_F/β (z is the fraction light-cone (+) momentum carried by the quark in the final state, β is the coefficient in the running coupling constant) times the skewed gluon distribution of the target.