Simulation studies of R2(Δη,Δφ) and P2(Δη,Δφ) correlation functions in pp collisions with the PYTHIA and HERWIG models

We report studies of charge-independent (CI) and charge-dependent (CD) two-particle differential-number correlation functions, R2(Δη,Δφ), and transverse momentum (pT) correlation functions, P2(Δη,Δφ), of charged particles in √s = 2.76 TeV pp collisions with the PYTHIA and HERWIG models. Model predictions are presented for inclusive charged hadrons (h±), as well as pions (π±), kaons (K±), and (anti-)protons (p¯/p) in the ranges 0.2 < pT ≤ 2.0 GeV/c, 2.0 < pT ≤ 5.0 GeV/c, and 5.0 < pT ≤ 30.0 GeV/c, with full azimuthal coverage in the range |η| < 1.0. We compare the model predictions for the strength and shape of the R2 and P2 correlators as these pertain to recent measurements by the ALICE collaboration. The R2 and P2 correlation functions estimated with PYTHIA and HERWIG exhibit qualitatively similar near-side and away-side correlation structures but feature important differences. Here, our analysis indicates that comparative studies of R2 and P2 correlation functions would provide valuable insight towards the understanding of particle production in pp collisions, and by extension, should also be useful in studies of heavy-ion collisions. Comparison of the Δη dependence of R2 and P2 could contribute, in particular, to a better understanding and modeling of the angular ordering of particles produced by hadronization in jets, as well as a better description of jet fragmentation functions of identified species at low momentum fraction (z).