Charged–particle multiplicities in proton–proton collisions at \(\sqrt{s}=\) 0.9 to 8 TeV, with ALICE at the LHC

Abstract

The ALICE Collaboration has carried out a detailed study of pseudorapidity densities and multiplicity distributions of primary charged particles produced in proton-proton collisions, at \(\sqrt{s} =\) 0.9, 2.36, 2.76, 7 and 8 TeV, in the pseudorapidity range \(|\eta| < 2\), Measurements were obtained for three event classes: inelastic, non-single diffractive and events with at least one charged particle in the pseudorapidity interval \(|\eta| < 1\), The use of an improved track-counting algorithm combined with ALICE’s measurements of diffractive processes allows a higher precision compared to our previous publications. A KNO scaling study was performed in the pseudorapidity intervals \(|\eta| < 0.5\), 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.