Kinematic biases on centrality selection of jet events in pPb collisions at the LHC

Abstract

Centrality selection has been observed to have a large effect on jet observables in pPb collisions at the Large Hadron Collider, stronger than that predicted by the nuclear modification of parton densities. We study to which extent simple considerations of energy-momentum conservation between the hard process and the underlying event affect jets observables in such collisions. We develop a simplistic approach that considers first the production of jets in a pp collision as described by PYTHIA. From each pp collision, the value of the energy of the parton from the proton participating in the hard scattering is extracted. Then, the underlying event is generated simulating a pPb collision through HIJING, but with the energy of the proton decreased according to the value extracted in the previous step, and both collisions are superimposed. This model is able to capture the bulk of the centrality effect for central to semicentral collisions, for the two available sets of data: dijets from the CMS Collaboration and single jets from the ATLAS Collaboration. As expected, the model fails for peripheral collisions where very few nucleons from Pb participate.

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Cited by in corpus (8)

• Novel Collective Phenomena in High-Energy Proton-Proton and Proton-Nucleus Collisions
• Constraints on jet quenching in p-Pb collisions at $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}$ = 5.02 TeV measured by the event-activity dependence of semi-inclusive hadron-jet distributions
• Heavy-ion collisions at the Large Hadron Collider: a review of the results from Run 1
• Neutron skin and centrality classification in high-energy heavy-ion collisions at the LHC
• Neutron-skin effect in direct-photon and charged hadron-production in Pb+Pb collisions at the LHC
• Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton-proton collisions at $\sqrt{s}=2.76$ TeV with ATLAS
• Short path length corrections to Djordjevic-Gyulassy-Levai-Vitev energy loss
• Effect of meson cloud on the jet nuclear modification factor in $pA$ collisions