Multiplicity and event-scale dependent flow and jet fragmentation in pp collisions at √s=13 TeV and in p-Pb collisions at √sNN=5.02 TeV

Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at root s = 13TeV and p-Pb collisions at root s(NN) = 5.02TeV. The correlation functions are measured as a function of relative azimuthal angle Delta phi and pseudorapidity separation Delta eta for pairs of primary charged particles within the pseudorapidity interval vertical bar eta vertical bar < 0.9 and the transverse-momentum interval 1 < p(T) < 4 GeV/c. Flow coefficients are extracted for the long-range correlations ( 1.6 < vertical bar Delta eta vertical bar < 1.8) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events.