Two-particle differential transverse momentum and number density correlations in p−Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV at the CERN Large Hadron Collider

Abstract

We present measurements of two-particle differential number correlation functionsR2and transverse momen-tum correlation functionsP2, obtained fromp-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV. Theresults are obtained by using charged particles in the pseudorapidity range|η|<1.0 and transverse momentumrange 0.2<pT<2.0 GeV/cas a function of pair separation in pseudorapidity,| η|, azimuthal angle φ,and for several charged-particle multiplicity classes. Measurements are carried out for like-sign and unlike-signcharged-particle pairs separately and combined to obtain charge-independent and charge-dependent correlationfunctions. We study the evolution of the width of the near-side peak of these correlation functions withcollision centrality. Additionally, we study Fourier decompositions of the correlators in φas a function of pairseparation| η|. Significant differences in the dependence of their harmonic coefficients on multiplicity classesare found. These differences can be exploited, in theoretical models, to obtain further insight into charged-particleproduction and transport in heavy-ion collisions. Moreover, an upper limit of nonflow contributions to flowcoefficientsvnmeasured in Pb-Pb collisions based on the relative strength of Fourier coefficients measured inp-Pb interactions is estimated.