Leading-twist shadowing, black disk regime and forward hadron production

We review theory of the leading-twist nuclear shadowing, and describe phenomenon of post-selection suppression of leading parton spectrum (effective fractional energy losses) in the proximity of the black disk regime. We argue that 2→2 mechanism dominates in the inclusive leading pion production in d-Au collisions and explain that the post-selection naturally explains both the magnitude of the suppression of the forward pion production in d-Au collisions and the pattern of the forward–central correlations. At the same time this pattern of correlations rules out 2→1 mechanism as the main source of the inclusive leading pion yield. It is demonstrated that the mechanism of the double-parton interactions gives an important contribution to the production of two leading pions in pp scattering opening a new way to study correlations of leading quarks in the nucleon. The same mechanism is enhanced in dAu→π0π0+X collisions and explains the dominance of Δφ independent component and suppression of the away side peak.