Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC

Abstract

The average transverse momentum 〈pT〉 versus the charged-particle multiplicity Nch was measured in p-Pb collisions at a collision energy per nucleon-nucleon pair sNN=5.02TeV and in pp collisions at collision energies of s=0.9,2.76, and 7TeV in the kinematic range 0.15 <0.3 with the ALICE apparatus at the LHC. These data are compared to results in Pb-Pb collisions at sNN=2.76TeV at similar charged-particle multiplicities. In pp and p-Pb collisions, a strong increase of 〈pT〉 with Nch is observed, which is much stronger than that measured in Pb-Pb collisions. For pp collisions, this could be attributed, within a model of hadronizing strings, to multiple-parton interactions and to a final-state color reconnection mechanism. The data in p-Pb and Pb-Pb collisions cannot be described by an incoherent superposition of nucleon-nucleon collisions and pose a challenge to most of the event generators. © 2013 CERN.