Remarks on the particle multiplicities at LHC energies

TL;DR

This paper compares ALICE LHC multiplicity data with PYTHIA 8 simulations, finds discrepancies in energy dependence, and demonstrates tuning parameters can improve model-data agreement.

Contribution

It provides a detailed comparison of LHC multiplicity data with PYTHIA 8 and shows how parameter tuning enhances model accuracy.

Findings

PYTHIA 8 overestimates multiplicity increase at LHC energies

Parameter tuning improves agreement with experimental data

Normalized moments depend on rapidity bin width and energy as predicted

Abstract

Recent ALICE data for the multiplicity distributions in the central rapidity bins at LHC energies are compared with the results from two default versions of the PYTHIA 8 generator. We find that, contrary to the earlier versions of PYTHIA, the model overestimates the increase of average multiplicity with energy. Tuning two of the model parameters one obtains reasonable agreement with data. The dependence of the normalized moments of the distribution on the rapidity bin width and on energy is also qualitatively correct.