Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at √s=5.02 and 13 TeV

Abstract

We present a study of the inclusive charged-particle transverse momentum ( Pᴛ ) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, dNch /dη, in pp collisions at √s = 5.02 and 13 TeV covering the kinematic range |η| < 0.8 and 0.15 < Pᴛ < 20 GeV/c. The results are presented for events with at least one charged particle in |η| < 1 (INEL > 0). The Pᴛ spectra are reported for two multiplicity estimators covering different pseudo-rapidity regions. The Pᴛ spectra normalized to that for INEL > 0 show little energy dependence. Moreover, the high- Pᴛ yields of charged particles increase faster than the charged-particle multiplicity density. The average Pᴛ as a function of multiplicity and transverse spherocity is reported for pp collisions at √s = 13 TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average Pᴛ is higher (smaller) than that measured in INEL > 0 pp collisions. Within uncertainties, the functional form of〈 Pᴛ 〉(Nch) is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average Pᴛ in jet-like events.