Multiplicity Distribution and Mechanisms of the High-Energy Hadron Collisions

TL;DR

This work analyzes multiplicity distributions in high-energy hadron collisions within a two-component framework combining Regge/Pomeron-based multi-parton interactions and a QCD gluon-string interpretation. By decomposing the inelastic cross section into soft single-parton and semi-hard multi-parton contributions, the authors extract $\sigma_1$ and $\sigma_2$ (and hints of $\sigma_3$) from data across ISR to Tevatron energies, showing $\sigma_1 \approx 34$ mb nearly energy-independent for $\sqrt{s} > 200$ GeV, while $\sigma_2$ grows with energy. The approach explains the observed violation of KNO scaling and the rising $\langle p_T\rangle$ with multiplicity, and predicts stronger multi-parton effects at LHC energies, including potential triple-parton collisions. The results support a two-component, energy-dependent picture of high-energy hadron interactions and emphasize the role of multi-parton dynamics in the inelastic cross section and particle production.

Abstract

We discuss the multiplicity distribution for highest accessible energies of $pp$- and $\bar pp$- interactions from the point of view of the multiparton collisions. The inelastic cross sections for the single, $σ_1$, and multiple (double and, presumably, triple, $σ_{2+3}$) parton collisions are extracted from the analysis of the experimental data on the multiplicity distribution up to the Tevatron energies. It follows that $σ_1$ becomes energy independent while $σ_{2+3}$ increases with $\sqrt{s}$ for $\sqrt{s}\ge$ 200 GeV. The observed growth of $<p_{\perp}>$ with multiplicity is attributed to the increasing role of multiparton collisions for the high energy $\bar pp(pp)$- inelastic interactions.

Figures (5)

• Figure 1: a) Topological cross sections $\sigma_N$ in the quasi-eikonal approximation with exchanges of three effective "soft" Pomerons for $\sqrt{s}$ = 546, 900, 1800 and $14.10^3$ GeV. b) Topological cross sections resulting from double and triple parton collisions for $\sqrt{s}$ = 546, 900, 1800 and $14.10^3$ GeV.
• Figure 2: Same in Fig. 1 for $\sqrt{s}$ = 100, 200 and 300 GeV.
• Figure 3: A comparison of multiplicity distributions at different values $\sqrt{s}$. The distributions are normalized at the maximum value of ${d\sigma\over dx}$ where $x={n\over \langle n_1\rangle}$. The solid curve is the KNO distribution from ISR data.
• Figure 4: Multiplicity distributions obtained by taking the difference between the $p\bar{p}$ collider data and the KNO distribution.
• Figure 5: Cross sections for the single $(\sigma_1)$ and multiparton (double and triple) $(\sigma_2)$ parton collisions as a function of $\sqrt{s}$.