CERN Accelerating science

Article
Report number arXiv:1807.11321 ; CERN-EP-2018-209
Title Multiplicity dependence of light-flavor hadron production in pp collisions at s = 7 TeV
Related titleMultiplicity dependence of light-flavor hadron production in pp collisions at s = 7 TeV
Author(s) ALICE Collaboration  显示全部 1019 名作者
Publication 2019-02-09
Imprint 23 Jul 2018
Number of pages 30
Note 45 pages, 15 captioned figures, 12 tables, authors from page 40, published, figures at http://alice-publications.web.cern.ch/node/4516
In: Phys. Rev. C 99 (2019) 024906
DOI 10.1103/PhysRevC.99.024906
Subject category Nuclear Physics - Experiment ; hep-ex ; Particle Physics - Experiment ; nucl-ex
Accelerator/Facility, Experiment CERN LHC ; ALICE
Free keywords QCD ; relativistic heavy ion physics ; quark gluon plasma ; particle and resonance production ; experimental results
Abstract Comprehensive results on the production of unidentified charged particles, π+, K±, K0S, K*(892)0, p, ¯p, ϕ(1020), Λ, ¯Λ, Ξ, ¯Ξ+, Ω and ¯Ω+ hadrons in proton-proton (pp) collisions at s = 7 TeV at midrapidity (|y|<0.5) as a function of charged-particle multiplicity density are presented. In order to avoid auto-correlation biases, the actual transverse momentum (pT) spectra of the particles under study and the event activity are measured in different rapidity windows. In the highest multiplicity class, the charged-particle density reaches about 3.5 times the value measured in inelastic collisions. While the yield of protons normalized to pions remains approximately constant as a function of multiplicity, the corresponding ratios of strange hadrons to pions show a significant enhancement that increases with increasing strangeness content. Furthermore, all identified particle to pion ratios are shown to depend solely on charged-particle multiplicity density, regardless of system type and collision energy. The evolution of the spectral shapes with multiplicity and hadron mass shows patterns that are similar to those observed in p-Pb and Pb-Pb collisions at LHC energies. The obtained pT distributions and yields are compared to expectations from QCD-based pp event generators as well as to predictions from thermal and hydrodynamic models. These comparisons indicate that traces of a collective, equilibrated system are already present in high-multiplicity pp collisions.
Copyright/License Preprint: © 2018-2024 CERN (License: CC-BY-4.0)



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