Multiplicity biased pA collisions in CCG framework

by Vladimir Skokov (Brookhaven national laboratory)

Thursday 22 Mar 2018, 10:30 → 12:00 Europe/Zurich

40/S2-D01 - Salle Dirac (CERN)

The nuclear modification factor RpA provides insights into the small-x gluon distribution of a nucleus at high energy hadron colliders. Several experimental collaborations have recently measured the nuclear modification  factor not only in minimum bias but also in central pA collisions. Their main observation is that the nuclear modification factor increases with centrality and that it displays a Cronin-like peak at transverse momenta of order 3 GeV. 

In this talk, in the saturation/CGC framework,  I analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. I demonstrate that, in contrast to a naive expectation, the biased nuclear modification factor QpA  for central collisions is above RpA  for minimum bias events, and that the bias may lead to a Cronin peak even at small x.