Gluon saturation and energy dependence of hadron multiplicity in pp and AA collisions at the LHC

Abstract

The recent results in \sqrt{s}=2.76 TeV Pb+Pb collisions at the Large Hadron Collider (LHC) reported by the ALICE collaboration shows that the power-law energy-dependence of charged hadron multiplicity in Pb+Pb collisions is significantly different from p+p collisions. We show that this different energy-dependence can be explained by inclusion of a strong angular-ordering in the gluon-decay cascade within the Color-Glass-Condensate (or gluon saturation) approach. This effect is more important in nucleus-nucleus collisions where the saturation scale is larger than 1 GeV. Our prescription gives a good description of the LHC data both in p+p and Pb+Pb collisions.

11 pages, 8 figures; v2: references added, results unchanged, discussion added about the centrality dependence of average transverse momentum over the charged-particle multiplicity at RHIC and the LHC. The version to appear in Phys. Rev. D

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Cited by in corpus (22)

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• Semi-inclusive photon-hadron production in pp and pA collisions at RHIC and LHC
• TMD factorization and the gluon distribution in high energy QCD
• CGC/saturation approach: a new impact-parameter dependent model in the next-to-leading order of perturbative QCD
• Diphoton production in high-energy p+A collisions
• A model for strong interactions at high energy based on the CGC/saturation approach
• CGC/saturation approach for soft interactions at high energy: inclusive production
• Role of nuclear gluon distribution on particle production in heavy ion collisions
• Universal geometrical scaling for hadronic interactions
• CGC/saturation approach for soft interactions at high energy: a two channel model
• Testing the running coupling $k_T$-factorization formula for the inclusive gluon production
• A CGC/saturation approach for angular correlations in proton-proton scattering
• Non-linear evolution in the re-summed next-to-leading order of perturbative QCD:\confronting the experimental data
• Forward Hadron Productions in high energy pp collisions from a Monte-Carlo generator for Color Glass Condensate
• Investigating saturation effects and the virtual pion in leading neutron events at HERA with the dipole model
• Thermal radiation and inclusive production in the running coupling $k_T$ -- factorization approach
• Energy dependence of the inelasticity in $pp/p\bar{p}$ collisions from experimental information on charged particle multiplicity distributions
• CGC and saturation approach: Impact-parameter dependent model of perturbative QCD and combined HERA data
• Proton structure functions at low $x$: the Fractal distributions
• Investigation of density structure of pseudorapidity fluctuations in interactions of Au 10.7 AGeV and Pb 158 AGeV nuclei with photoemulsion nuclei by Hurst method