Color transparency and nuclear shadowing

Recent works have shown that shadowing effects, observed in hadron and photon interactions with nuclei are due to quantum-mechanical coherence and interference. For q q-bar production on nuclear targets, this model allows to estimate nuclear cross-sections in a direct way. In the present work, this procedure has been used in order to compute cross-sections corresponding to cc-bar nucleon interactions for a range of photon energies and nuclear targets. The model describes the relation between σ(γA → q q-bar) and Aσ(γN → q q-bar) in terms of the size of coherence Zc relative to nuclear parameters as the mean free path λ of the q q-bar fluctuation, the average inter nucleonic distance d, and the uniform-equivalent volume nucleus radius R, for the regimes of shadowing, anti shadowing, incoherence and vector meson dominance