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Torsten ÅKESSON

Torsten Åkesson

Professor Emeritus / Expert

Torsten ÅKESSON

Disentangling Sources of Momentum Fluctuations in (Formula presented) and (Formula presented) Collisions with the ATLAS Detector

Author

  • G. Aad
  • T.P.A. Åkesson
  • K.S.V. Astrand
  • C. Doglioni
  • P.A. Ekman
  • V. Hedberg
  • H. Herde
  • B. Konya
  • E. Lytken
  • R. Poettgen
  • N.D. Simpson
  • O. Smirnova
  • E.J. Wallin
  • L. Zwalinski
Show all

Summary, in English

High-energy nuclear collisions create a quark-gluon plasma, whose initial condition and subsequent expansion vary from event to event, impacting the distribution of the eventwise average transverse momentum [(Formula presented)]. Disentangling the contributions from fluctuations in the nuclear overlap size (geometrical component) and other sources at a fixed size (intrinsic component) remains a challenge. This problem is addressed by measuring the mean, variance, and skewness of (Formula presented) in (Formula presented) and (Formula presented) collisions at (Formula presented) and 5.44 TeV, respectively, using the ATLAS detector at the LHC. All observables show distinct features in ultracentral collisions, which are explained by a suppression of the geometrical component as the overlap area reaches its maximum. These results demonstrate a new technique to separate geometrical and intrinsic fluctuations, providing constraints on initial conditions and properties of the quark-gluon plasma, such as the speed of sound. © 2024 CERN, for the ATLAS Collaboration.

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration
  • Department of Physics

Publishing year

2024

Language

English

Publication/Series

Physical Review Letters

Volume

133

Issue

25

Document type

Journal article

Publisher

American Physical Society

Topic

  • Subatomic Physics

Keywords

  • Acoustic properties
  • Colliding beam accelerators
  • Collisionless plasmas
  • Elementary particle sources
  • Momentum
  • Photons
  • Plasma collision processes
  • ATLAS detectors
  • Energy
  • Fixed size
  • Geometrical fluctuations
  • Initial conditions
  • Mean variance
  • Momentum fluctuations
  • Nuclear collisions
  • Quark-gluon plasma
  • Transverse momenta
  • Collisional plasmas

Status

Published

ISBN/ISSN/Other

  • ISSN: 0031-9007