Forward-backward multiplicity correlations in proton-proton collisions from several GeV to LHC energies

L Bravina,E Zabrodin,J Bleibel,R Emaus,S Kabana,Y Foka

doi:10.1051/epjconf/201716407015

Abstract

Forward-backward multiplicity correlations in pp collisions at LHC energies are studied with the quark-gluon string model. Comparison with experimental data and with model calculations for lower energies is performed. The model correctly reproduces the linear slope of the correlations, 〈nB (nF )〉 = a + bcorr nF , in the whole energy interval. Positive correlations arise because of mixing of sub-processes with different mean multiplicities. The increase of bcorr with rising collision energy is linked to the increase of the variety of sub-processes going via the soft and hard multi-Pomeron exchanges. For the events with fixed amount of Pomerons the correlation slope bcorr is shown to be essentially zero.

Highlights

The first observation of significant positive correlations between the multiplicity of charged particles emitted in forward and backward hemispheres in pp collisions at ISR energies was considered as evidence of long range correlations between the “clusters" of fragmenting system [1]
quark-gluon string model (QGSM) was successfully applied for the description of FB correlations in pp an√d pp collisions at plab = 32 GeV/c [10], and recently in pp collisions at LHC energies 900 GeV ≤ s ≤ 13 TeV [19]
Is shown that positive FB correlations arise in QGSM because of addition of different sub-processes with different mean multiplicities

Summary

Introduction

The first observation of significant positive correlations between the multiplicity of charged particles emitted in forward and backward hemispheres in pp collisions at ISR energies was considered as evidence of long range correlations between the “clusters" of fragmenting system [1]. This phenomenon has attracted a lot of attention, see e.g. QGSM was successfully applied for the description of FB correlations in pp an√d pp collisions at plab = 32 GeV/c [10], and recently in pp collisions at LHC energies 900 GeV ≤ s ≤ 13 TeV [19] Results of the both studies are presented below

FB correlations in pp and pp interactions at intermediate energies

FB correlations at LHC energies

Conclusions