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

Abstract

The average transverse momentum 〈pT〉〈pT〉 versus the charged-particle multiplicity NchNch was measured in p–Pb collisions at a collision energy per nucleon–nucleon pair root sNN=5.02 TeV and in pp collisions at collision energies of root s=0.9,2.76, and 7 TeV in the kinematic range 0.15[?]pT[?]10.0 GeV/c0.15[?]pT[?]10.0 GeV/c and |η|<0.3|η|<0.3 with the ALICE apparatus at the LHC. These data are compared to results in Pb–Pb collisions at root sNN=2.76 TeV at similar charged-particle multiplicities. In pp and p–Pb collisions, a strong increase of 〈pT〉〈pT〉 with NchNch 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.