Key points are not available for this paper at this time.
The observation of double parton collisions by the Collider Detector at Fermilab provided the first direct information on the structure of the proton in transverse space. The actual quantity measured is the ``effective cross section'' ₄₅₅, which is related to the transverse size of the region where hard interactions are localized. The measured value is sizably smaller than naively expected and it is an indication of important correlation effects in the many-body parton distribution of the proton. We discuss the problem pointing out a possible source of correlations in the proton structure which could have a significant effect on the value of ₄₅₅.
Calucci et al. (Mon,) studied this question.