Empirical parameterization of the high energy behaviour of average charged particle multiplicities in e+e-, ep and pp collisions

TL;DR

This paper analyzes existing high-energy collision data to empirically model how average charged particle multiplicities scale with energy across different collision types, predicting multiplicities at LHC energies.

Contribution

It introduces a simple power law parameterization for charged particle multiplicities in various collisions, unifying their energy dependence with a common trend.

Findings

Multiplicity in pp and p̄p follows N_ch = N_0*(s/s_0)^(γ) with γ ≈ 1/5

In e+e- and ep collisions, multiplicities follow the same law with a constant offset

At 7 TeV, the expected average multiplicity is around 80 particles.

Abstract

A simple fit of existing data for center-of-mass energies above the b-threshold shows that the average charged particle multiplicities in pp_bar and pp interactions can be parameterized by a simple power law N_ch = N_0*(s/s_0)^(gamma) with gamma close to 1/5. Choosing s_0=m_p^2, where m_p is a proton mass, one finds N_0=2.32. The average charged particle multiplicities in e+e- and e(+/-)p interactions follows the same power law with an offset of +/- 1 unit in N_0. The observed trend leads to the conclusion that in LHC experiments at energy of 7TeV one should expect the average charge multiplicity in the region of N_ch close to 80.