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Identified Hadron Production as a Function of Event Multiplicity and Transverse Spherocity in pp Collisions at √s = 7 and 13 TeV with the ALICE Detector

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Author

Summary, in English

This study reports on identified hadron production as a function of event multiplicity (dNch/dη) and transverse spherocity (SO) in proton-proton collisions at √s = 7 and 13 TeV measured with the ALICE detector at the LHC. The particle spectra and their ratios measured in high-multiplicity events show signatures of an expanding medium. Integrated particle yields as a function of multiplicity measured in pp collisions at √s = 7 and 13 TeV are compared to those measured in p-Pb and Pb-Pb collisions. Hadrochemical composition of particles are found to be similar in different colliding systems under different √s, provided similar multiplicities are compared. This suggests that hadron yields are dominantly driven by dNch/dη , and not the colliding system or center-of-mass energy. On the other hand, particle spectra measured in pp collisions at √s = 13 TeV is harder than that at 7 TeV, when similar dNch/dη are compared. In addition, hadron production as a function of multiplicity is studied in the context of statistical, hydrodynamical and pQCD-inspired models. In order to disentangle the soft QCD component from the hard, high-multiplicity pp collisions at √s = 13 TeV are studied as a function of transverse spherocity. It is found that the amount of flow-like effects in the data sample can be controlled using event shape observables.

Publishing year

2018-02

Language

English

Document type

Dissertation

Publisher

Lund University, Faculty of Science, Department of Physics

Topic

  • Subatomic Physics

Keywords

  • LHC
  • ALICE
  • small systems
  • QGP
  • collectivity
  • multiplicity
  • spherocity
  • event shapes
  • pp collisions
  • Fysicumarkivet A:2018:Vislavicius

Status

Published

ISBN/ISSN/Other

  • ISBN: 978-91-7753-597-3
  • ISBN: 978-91-7753-596-6

Defence date

23 March 2018

Defence time

13:00

Defence place

Rydberg lecture hall, Department of Physics, Sölvegatan 14A, Lund

Opponent

  • Thomas Hemmick (Professor)