CERN Accelerating science

The dissertation discusses the pseudorapidity density dNch/deta and the multiplicity distribution of charged particles in high-energy proton-proton collisions with the ALICE experiment at the CERN Large Hadron Collider (LHC). The theoretical framework for the description of multi-particle production is explained and measurements of other experiments at center-of-mass energies from 6 GeV to 1.8 TeV are discussed. Analyses for both measurements with two different detectors (silicon pixel detector and time-projection chamber) are described and the associated systematic errors are evaluated. The analyses take experimental effects like for example acceptance, secondary-particle production, and trigger efficiency into account. The multiplicity distribution is unfolded with two different methods: one based on the minimization of a chi2-function, the other on Bayes' theorem. Predictions for the distributions up to the highest LHC energy of 14 TeV are discussed.