Revealing “flickering” of the interaction strength in pA collisions at the CERN LHC

Alvioli M.; Frankfurt L.; Guzey V.; Strikman M., 2014, Revealing “flickering” of the interaction strength in pA collisions at the CERN LHC, Physical review. C. Nuclear physics (Print) 90 (2014): 034914-1–034914-16. doi_10.1103/PhysRevC.90.034914,
URL: http://www.cnr.it/prodotto/i/332265

Using the high-energy color fluctuation formalism to include inelastic diffractive processes and taking into account the collision geometry and short-range nucleon-nucleon correlations in nuclei, we assess various manifestations of "flickering" of the parton wave function of a rapid proton in pA interactions focusing at energies available at the CERN Large Hadron Collider (LHC) in soft QCD processes and in the special soft QCD processes accompanying hard processes. We evaluate the number of wounded nucleons, Ncoll - the number of inelastic collisions of projectiles - in these processes and find a nontrivial relation between the hard collision rate and centrality. We study the distribution over Ncoll for a hard trigger selecting configurations in the nucleon with the strength larger or smaller than the average one and argue that the pattern observed in the LHC pA measurements by CMS and ATLAS for jets carrying a large fraction of the proton momentum, xp, is consistent with the expectation that these configurations interact with the strength which is significantly smaller than the average one, a factor of two smaller for xp~0.5. We also study the leading twist shadowing and the European Muon Collaboration effects for superdense nuclear matter configurations probed in the events with a larger-than-average number of wounded nucleons. We also argue that taking into account energy-momentum conservation does not change the distribution over Ncoll but suppresses hadron production at central rapidities.

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