Charged-particle multiplicities in proton–proton collisions at √s = 0.9 to 8 TeV

Abstract

A detailed study of pseudorapidity densities and multiplicity distributions of primary charged particles pro- duced in proton–proton collisions, at √s = 0.9, 2.36, 2.76, 7 and 8 TeV, in the pseudorapidity range |η| < 2, was carried out using the ALICE detector. Measurements were obtained for three event classes: inelastic, non-single diffractive and events with at least one charged particle in the pseudorapidity interval |η| < 1. The use of an improved track-counting algo- rithm combined with ALICE’s measurements of diffractive processes allows a higher precision compared to our previ- ous publications. A KNO scaling study was performed in the pseudorapidity intervals |η| < 0.5, 1.0 and 1.5. The data are compared to other experimental results and to models as implemented in Monte Carlo event generators PHOJET and recent tunes of PYTHIA6, PYTHIA8 and EPOS.