pp collisions at collider energies: triggers, final states, and implications for physics near GZK

by Mark Strikman (Penn State University)

Friday 18 Jun 2004, 14:00 → 15:00 Europe/Zurich

TH Auditorium (CERN)

Based on the analysis of the information on the structure of the gluon field of the nucleon obtained at HERA, we demonstrate that at LHC new particle production and hard dijet production at central rapidities are dominated by pp scattering at small impact parameters. We argue that under these conditions the strength of gluon interactions for a wide range of virtualities approaches the unitarity ('black-body') limit. This leads to specific modifications of the final state, such as a higher probability of multijet events at small rapidities, a strong increase of the transverse momenta and depletion of the longitudinal momenta at large rapidities, and the appearance of long-range correlations in rapidity between the forward/backward fragmentation regions. Studies of the regime of strong gluon fields would be feasible with the CMS-TOTEM detector setup using dijets as a trigger. These studies will help to understand the underlying structure of the events relevant for the new particle searches at LHC. A similar pattern is expected for generic central proton-nucleus collisions at the LHC and beyond with the most dramatic changes in the forward region important for interpretation of the cosmic ray interactions near the GZK cut-off.